Patent Application
20230418068
This disclosure generally relates to near-eye display apparatuses and illumination systems therefor.
Head-worn displays incorporating a near-eye display apparatus may be arranged to provide fully immersive imagery such as in virtual reality (VR) displays or augmented imagery overlayed over views of the real world such as in augmented reality (AR) displays. If the overlayed imagery is aligned or registered with the real-world image it may be termed Mixed Reality (MR). In VR displays, the near-eye display apparatus is typically opaque to the real world, whereas in AR displays the optical system is partially transmissive to light from the real world.
The near-eye display apparatuses of AR and VR displays aim to provide images to at least one eye of a user with full colour, high resolution, high luminance and high contrast; and with wide fields of view (angular size of image), large eyebox sizes (the geometry over which the eye can move while having visibility of the full image field of view). Such displays are desirable in thin form factors, low weight and with low manufacturing cost and complexity.
Further, AR near-eye display apparatuses aim to have high transmission of real-world light rays without image distortions or degradations and reduced glare of stray light away from the display wearer. AR optics may broadly be categorised as reflective combiner type or waveguide type. Waveguide types typically achieve reduced form factor and weight due to the optical path folding within the waveguide. Known methods for injecting images into a waveguide may use a spatial light modulator and a projection lens arrangement with a prism or grating to couple light into the waveguide. Pixel locations in the spatial light modulator are converted to a fan of ray directions by the projection lens. In other arrangements a laser scanner may provide the fan of ray directions. The angular locations are propagated through the waveguide and output to the eye of the user. The eye's optical system collects the angular locations and provides spatial images at the retina.
According to a first aspect of the present disclosure, there is provided an anamorphic near-eye display apparatus comprising: an illumination system comprising a spatial light modulator, the illumination system arranged to output light; and an optical system arranged to direct light from the illumination system to a viewer's eye, wherein the optical system has an optical axis and has anamorphic properties in a lateral direction and a transverse direction that are perpendicular to each other and perpendicular to the optical axis, wherein the spatial light modulator comprises pixels distributed in the lateral direction, and the optical system comprises: a transverse anamorphic component having positive optical power in the transverse direction, wherein the transverse anamorphic component is arranged to receive light from the spatial light modulator and the illumination system is arranged so that light output from the transverse anamorphic component is directed in directions that are distributed in the transverse direction; an extraction waveguide arranged to receive light from the transverse anamorphic component; a lateral anamorphic component having positive optical power in the lateral direction, the extraction waveguide arranged to guide light from the transverse anamorphic component to the lateral anamorphic component along the extraction waveguide in a first direction; and a light reversing reflector that is arranged to reflect light that has been guided along the extraction waveguide in the first direction so that the reflected light is guided along the extraction waveguide in a second direction opposite to the first direction, wherein the extraction waveguide comprises an array of extraction features, the extraction features arranged to transmit light guided along the extraction waveguide in the first direction and to extract light guided along the extraction waveguide in the second direction towards an eye of a viewer, the array of extraction features distributed along the extraction waveguide so as to provide exit pupil expansion, and the lateral anamorphic component comprises: a reflective linear polariser disposed between the light reversing reflector and the array of extraction features; and a polarisation conversion retarder disposed between the reflective linear polariser and the light reversing reflector, the polarisation conversion retarder arranged to convert a polarisation state of light passing therethrough between a linear polarisation state and a circular polarisation state.
Aberrations of the optical system in at least the lateral direction may advantageously be reduced. Image blur of pixels as seen by the viewer may be reduced and image contrast advantageously increased. A compact and thin optical system may be provided that may be partially transparent for augmented reality operation. Increased field of view in the lateral direction for desirable maximum image blur may be achieved.
The reflective linear polariser may be curved in the lateral direction. The reflective linear polariser may be curved in only one plane may be conveniently formed from a flexible layer without distortion. Advantageously image fidelity may be increased.
The light reversing reflector may not be curved in the lateral direction. The anamorphic near-eye display apparatus may be provided with end shapes other than those provided by a curved light reversing reflector and with desirable outer shape.
The light reversing reflector may be curved in the lateral direction. Advantageously aberrations may be reduced.
The polarisation conversion retarder may be curved in the lateral direction. The polarisation conversion retarder may be formed near to the light reversing reflector, reducing complexity of assembly.
The polarisation conversion retarder may have a retardance of a quarter wavelength at a wavelength of visible light. Advantageously high efficiency of throughput of light through the lateral anamorphic component may be achieved over a wide field angle.
The optical system may comprise an input linear polariser disposed between the spatial light modulator and the array of extraction reflectors, wherein the input linear polariser and the reflective linear polariser of the lateral anamorphic component may be arranged to pass a common polarisation state. Stray light reflected from the reflective polariser may be reduced and advantageously image contrast improved.
The lateral anamorphic component may further comprise: a polarisation control retarder disposed between the reflective linear polariser and the array of extraction features, the polarisation control retarder arranged to change a polarisation state of light passing therethrough; and an absorbing linear polariser disposed between the polarisation control retarder and the reflective linear polariser, wherein the absorbing linear polariser and the reflective linear polariser may be arranged to pass a common linear polarisation state that may be a component of the polarisation state output from the polarisation control retarder in the direction along the waveguide. In operation, light of an input polarisation state may propagate in the first direction and light of an output polarisation state orthogonal to the input polarisation state may propagate in the second direction. The polarisation control retarder may have a retardance of a quarter wavelength or a half wavelength at a wavelength of visible light. The optical system may comprise an input linear polariser disposed between the spatial light modulator and the array of extraction reflectors. Stray light may be reduced and efficiency of light extraction may be increased. Advantageously image contrast may be increased.
The extraction features may be reflective extraction features disposed internally within the extraction waveguide. The reflective extraction features may comprise extraction reflectors that extend across at least part of the extraction waveguide between front and rear guide surfaces of the extraction waveguide. The extraction reflectors may comprise intermediate surfaces spaced apart by a partially reflective coating. Advantageously surface scatter artefacts may be reduced and image contrast improved.
The partially reflective coating may comprise at least one dielectric layer. Polarised light propagating in the first direction with the input polarisation state may be preferentially transmitted and polarised light with a different polarisation state to the input polarisation state propagating in the second direction may be preferentially extracted. Efficiency may be increased and image contrast advantageously reduced.
The extraction reflectors may have a surface normal direction that may be inclined with respect to the direction along the waveguide by an angle in the range 20 to 40 degrees, preferably by an angle in the range 25 to 35 degrees and most preferably by an angle in the range 27.5 degrees to 32.5 degrees. Advantageously the visibility of a flipped image in the transverse direction may be reduced.
The extraction waveguide may have a front guide surface and a rear guide surface, and the rear guide surface may comprise extraction facets that may be the extraction features, each extraction facet arranged to reflect light guided in the second direction towards an eye of a viewer through the front guide surface. Advantageously the cost and complexity of fabrication of the extraction waveguide may be reduced. High efficiency of operation may be achieved.
The extraction waveguide may have a front guide surface and a rear guide surface, and the rear guide surface may comprise a diffractive optical element comprising the extraction features. Advantageously the cost and complexity of assembling the extraction waveguide may be reduced.
The extraction waveguide may comprise: a front guide surface, a polarisation-sensitive reflector opposing the front guide surface; and an extraction element disposed outside the polarisation-sensitive reflector, wherein the extraction element may comprise: a rear guide surface opposing the front guide surface; and the array of extraction features; the anamorphic near-eye display apparatus may be arranged to provide light guided along the extraction waveguide in the first direction with an input linear polarisation state before reaching the polarisation-sensitive reflector; the polarisation conversion retarder disposed between the reflective linear polariser and the light reversing reflector may be a first polarisation conversion retarder; the anamorphic near-eye display apparatus may comprise a second polarisation conversion retarder arranged between the polarisation-sensitive reflector and the reflective linear polariser, the second polarisation conversion retarder arranged to convert from a state that may be parallel or orthogonal to the input linear polarisation state to a polarisation state that may have a component parallel to the input linear polarisation state and a component orthogonal to the input linear polarisation state; the anamorphic near-eye display apparatus may comprise an absorptive linear polariser arranged to pass the component parallel to the input linear polarisation state or the component orthogonal to the input linear polarisation state; the reflective linear polariser may be arranged to pass the same component as the absorptive linear polariser; the second polarisation conversion retarder, the absorptive linear polariser, the reflective linear polariser, the first polarisation conversion retarder and the light reversing reflector may be arranged in combination to rotate the input linear polarisation state of the light guided in the first direction so that the light guided in the second direction and output from the second polarisation conversion retarder may have a linear polarisation state that may have a component parallel to the input linear polarisation state and a component orthogonal to the input linear polarisation state; and the polarisation-sensitive reflector may be arranged to reflect light guided in the first direction having the input linear polarisation state and to pass the component of light guided in the second direction that may be orthogonal to the input linear polarisation state, so that the front guide surface and the polarisation-sensitive reflector may be arranged to guide light in the first direction, and the front guide surface and the rear guide surface may be arranged to guide the component of light that may be orthogonal to the input linear polarisation state in the second direction. The polarisation-sensitive reflector may comprise a reflective linear polariser. The polarisation-sensitive reflector may comprise at least one dielectric layer. A near-eye anamorphic display apparatus may be provided with reduced image blur at least in the lateral direction. The visibility of stray light and flipped images in the lateral direction may be reduced. Complexity of manufacture of the extraction waveguide may be reduced.
According to a second aspect of the present disclosure, there is provided a head-worn display apparatus comprising an anamorphic near-eye display apparatus according to the first aspect and a head-mounting arrangement arranged to mount the anamorphic near-eye display apparatus on a head of a wearer with the anamorphic near-eye display apparatus extending across at least one eye of the wearer. A display apparatus suitable for virtual reality and augmented reality applications may be provided.
According to a third aspect of the present disclosure, there is provided an anamorphic near-eye display apparatus comprising: an illumination system comprising a spatial light modulator, the illumination system arranged to output light; and an optical system arranged to direct light from the illumination system to a viewer's eye, wherein the optical system has an optical axis and has anamorphic properties in a lateral direction and a transverse direction that are perpendicular to each other and perpendicular to the optical axis, wherein the spatial light modulator comprises pixels distributed in the lateral direction, and the optical system comprises: a transverse anamorphic component having positive optical power in the transverse direction, wherein the transverse anamorphic component is arranged to receive light from the spatial light modulator and the illumination system is arranged so that light output from the transverse anamorphic component is directed in directions that are distributed in the transverse direction; an extraction waveguide arranged to receive light from the transverse anamorphic component; a lateral anamorphic component having positive optical power in the lateral direction, the extraction waveguide arranged to guide light from the transverse anamorphic component to the lateral anamorphic component along the extraction waveguide in a first direction; and a light reversing reflector that is arranged to reflect light that has been guided along the extraction waveguide in the first direction so that the reflected light is guided along the extraction waveguide in a second direction opposite to the first direction, wherein the extraction waveguide comprises an array of extraction features, the extraction features arranged to transmit light guided along the extraction waveguide in the first direction and to extract light guided along the extraction waveguide in the second direction towards an eye of a viewer, the array of extraction features distributed along the extraction waveguide so as to provide exit pupil expansion, and the transverse anamorphic component comprises: a partially reflective surface; a reflective linear polariser disposed in series with the partially reflective surface, wherein at least one of the partially reflective surface and the reflective linear polariser has positive optical power in the transverse direction; and a polarisation conversion retarder disposed between the partially reflective surface and the reflective linear polariser, the polarisation conversion retarder arranged to convert a polarisation state of light passing therethrough between a linear polarisation state and a circular polarisation state. Aberrations of the optical system in at least the transverse direction may advantageously be reduced. Image blur of pixels as seen by the viewer may be reduced and image contrast advantageously increased. A compact transverse anamorphic component may be provided. Increased field of view in the transverse direction for desirable maximum image blur may be achieved.
Each of the partially reflective surface and the reflective linear polariser may have positive optical power in the transverse direction. The partially reflective surface and the reflective linear polariser may be curved in only one plane so may be conveniently formed from a flexible layer without distortion. Advantageously image fidelity may be increased.
At least one of the partially reflective surface and the reflective linear polariser that has positive optical power in the transverse direction may have no optical power in the lateral direction. Advantageously the complexity and cost of fabrication may be reduced.
The transverse anamorphic component may further comprise at least one lens element. Advantageously aberrations may be further reduced and image fidelity increased.
The reflective linear polariser may be disposed after the partially reflective surface in a direction of transmission of light from the spatial light modulator or the reflective linear polariser may be disposed before the partially reflective surface in a direction of transmission of light from the spatial light modulator. Desirable aberrational performance may be achieved by appropriate selection of the sequence of the reflective linear polariser and the partially reflective surface.
The extraction waveguide may have an input end extending in the lateral and transverse directions, the extraction waveguide arranged to receive light from the illumination system through the input end, and the transverse anamorphic component may be disposed between the spatial light modulator and the input end of the extraction waveguide. Transverse ray bundles may be directed into the extraction waveguide, advantageously providing desirable field of view of operation by the viewer.
The transverse anamorphic component may further comprise a further polarisation conversion retarder that either may be disposed before the partially reflective surface and the reflective linear polariser in a direction of transmission of light from the spatial light modulator or may be disposed after the partially reflective surface and the reflective linear polariser in a direction of transmission of light from the spatial light modulator.
The anamorphic near-eye display apparatus may further comprise a linear polariser arranged between the transverse anamorphic component and the input end of the extraction waveguide. The spatial light modulator may be arranged to output linearly polarised light. The illumination system may further comprise an output polariser disposed between the spatial light modulator and the transverse optical component, the output polariser arranged to output linearly polarised light. The polarisation state propagating in the first direction along the waveguide may be provided with desirable orientation to achieve high efficiency and high image contrast.
According to a fourth aspect of the present disclosure, there is provided an anamorphic near-eye display apparatus comprising: an illumination system comprising a spatial light modulator, the illumination system arranged to output light; and an optical system arranged to direct light from the illumination system to a viewer's eye, wherein the optical system has an optical axis and has anamorphic properties in a lateral direction and a transverse direction that are perpendicular to each other and perpendicular to the optical axis, wherein the spatial light modulator comprises pixels distributed in the lateral direction, and the optical system comprises: a transverse anamorphic component having positive optical power in the transverse direction, wherein the transverse anamorphic component is arranged to receive light from the spatial light modulator and the illumination system is arranged so that light output from the transverse anamorphic component is directed in directions that are distributed in the transverse direction; an extraction waveguide arranged to receive light from the transverse anamorphic component; a lateral anamorphic component having positive optical power in the lateral direction, the extraction waveguide arranged to guide light from the transverse anamorphic component to the lateral anamorphic component along the extraction waveguide in a first direction; and a light reversing reflector that is arranged to reflect light that has been guided along the extraction waveguide in the first direction so that the reflected light is guided along the extraction waveguide in a second direction opposite to the first direction, wherein the extraction waveguide comprises an array of extraction features, the extraction features arranged to transmit light guided along the extraction waveguide in the first direction and to extract light guided along the extraction waveguide in the second direction towards an eye of a viewer, the array of extraction features distributed along the extraction waveguide so as to provide exit pupil expansion, and wherein the lateral anamorphic component comprises a lens formed by at least one surface of an air gap formed in a waveguide. Advantageously improved aberrations may be achieved across the field of view and for a larger exit pupil.
The lens of the lateral anamorphic component may comprise an air gap and a surface facing the air gap. Control of aberrations may be increased and advantageously the modulation transfer function for off-axis directions may be increased and the image blur reduced.
The air gap may have edges, and the anamorphic near-eye display apparatus may comprise reflectors extending across the edges of the air gap. Advantageously light losses may be reduced and image uniformity increased.
The waveguide in which the air gap may be formed may be the extraction waveguide. The light reversing reflector may be a reflective end of the extraction waveguide. The lateral anamorphic component may further comprise the light reversing reflector. Advantageously a compact display apparatus with improved aberrations may be achieved.
According to a fifth aspect of the present disclosure, there is provided an anamorphic near-eye display apparatus comprising: an illumination system comprising a spatial light modulator, the illumination system arranged to output light; and an optical system arranged to direct light from the illumination system to a viewer's eye, wherein the optical system has an optical axis and has anamorphic properties in a lateral direction and a transverse direction that are perpendicular to each other and perpendicular to the optical axis, wherein the spatial light modulator comprises pixels distributed in the lateral direction, and the optical system comprises: a transverse anamorphic component having positive optical power in the transverse direction, wherein the transverse anamorphic component is arranged to receive light from the spatial light modulator and the illumination system is arranged so that light output from the transverse anamorphic component is directed in directions that are distributed in the transverse direction; an extraction waveguide arranged to receive light from the transverse anamorphic component; a lateral anamorphic component having positive optical power in the lateral direction, the extraction waveguide arranged to guide light from the transverse anamorphic component to the lateral anamorphic component along the extraction waveguide in a first direction; and a light reversing reflector that is arranged to reflect light that has been guided along the extraction waveguide in the first direction so that the reflected light is guided along the extraction waveguide in a second direction opposite to the first direction, wherein the extraction waveguide comprises an array of extraction features, the extraction features arranged to transmit light guided along the extraction waveguide in the first direction and to extract light guided along the extraction waveguide in the second direction towards an eye of a viewer, the array of extraction features distributed along the extraction waveguide so as to provide exit pupil expansion, and the lens of the lateral anamorphic component is a Pancharatnam-Berry lens. Advantageously the size of the lateral anamorphic component may be reduced.
According to a sixth aspect of the present disclosure, there is provided an anamorphic near-eye display apparatus comprising: an illumination system comprising a spatial light modulator, the illumination system arranged to output light; and an optical system arranged to direct light from the illumination system to a viewer's eye, wherein the optical system has an optical axis and has anamorphic properties in a lateral direction and a transverse direction that are perpendicular to each other and perpendicular to the optical axis, wherein the spatial light modulator comprises pixels distributed in the lateral direction, and the optical system comprises: a transverse anamorphic component having positive optical power in the transverse direction, wherein the transverse anamorphic component is arranged to receive light from the spatial light modulator and the illumination system is arranged so that light output from the transverse anamorphic component is directed in directions that are distributed in the transverse direction; an extraction waveguide arranged to receive light from the transverse anamorphic component; a lateral anamorphic component having positive optical power in the lateral direction, the extraction waveguide arranged to guide light from the transverse anamorphic component to the lateral anamorphic component along the extraction waveguide in a first direction; and a light reversing reflector that is arranged to reflect light that has been guided along the extraction waveguide in the first direction so that the reflected light is guided along the extraction waveguide in a second direction opposite to the first direction, wherein the extraction waveguide comprises an array of extraction features, the extraction features arranged to transmit light guided along the extraction waveguide in the first direction and to extract light guided along the extraction waveguide in the second direction towards an eye of a viewer, the array of extraction features distributed along the extraction waveguide so as to provide exit pupil expansion, and at least one of an input end of the extraction waveguide, the transverse anamorphic component and the spatial light modulator has a curvature in the lateral direction that compensates for field curvature of the lateral anamorphic component. Advantageously the modulation transfer function for off-axis directions may be increased and the image blur reduced. Increased image fidelity and higher image contrast may be observed by the viewer.
According to a seventh aspect of the present disclosure, there is provided an anamorphic near-eye display apparatus comprising: an illumination system comprising a spatial light modulator, the illumination system arranged to output light; and an optical system arranged to direct light from the illumination system to a viewer's eye, wherein the optical system has an optical axis and has anamorphic properties in a lateral direction and a transverse direction that are perpendicular to each other and perpendicular to the optical axis, wherein the spatial light modulator comprises pixels distributed in the lateral direction, and the optical system comprises: a transverse anamorphic component having positive optical power in the transverse direction, wherein the transverse anamorphic component is arranged to receive light from the spatial light modulator and the illumination system is arranged so that light output from the transverse anamorphic component is directed in directions that are distributed in the transverse direction; an extraction waveguide arranged to receive light from the transverse anamorphic component; a lateral anamorphic component having positive optical power in the lateral direction, the extraction waveguide arranged to guide light from the transverse anamorphic component to the lateral anamorphic component along the extraction waveguide in a first direction; and a light reversing reflector that is arranged to reflect light that has been guided along the extraction waveguide in the first direction so that the reflected light is guided along the extraction waveguide in a second direction opposite to the first direction, wherein the extraction waveguide comprises an array of extraction features, the extraction features arranged to transmit light guided along the extraction waveguide in the first direction and to extract light guided along the extraction waveguide in the second direction towards an eye of a viewer, the array of extraction features distributed along the extraction waveguide so as to provide exit pupil expansion, and the spatial light modulator comprises an array of pixels, wherein each pixel comprises sub-pixels of plural colour components and a pitch of the sub-pixels of each colour component across the pixels in the lateral direction varies between the colour components in a manner that compensates for chromatic aberration between light of the colour components. The separation of separate colour components that arises at least from refraction at the front light guide surface and is seen by the viewer as colour blur may be reduced, achieving increased image fidelity for colour images. The appearance of image distortion may be reduced and active area of the viewed image increased.
The sub-pixels of each pixel may be aligned in the transverse direction. The pitch of the sub-pixels of each colour component across the pixels in the transverse direction may be the same for each colour component. The pitch of the sub-pixels of each colour component across the pixels in the transverse direction varies between the colour components in a manner that compensates for chromatic aberration between light of the colour components. Advantageously the complexity and cost of fabrication of the spatial light modulator may be reduced.
According to an eighth aspect of the present disclosure, there is provided an anamorphic near-eye display apparatus according to any one of the third to seventh aspects, wherein: the extraction waveguide comprises: a front guide surface; a polarisation-sensitive reflector opposing the front guide surface; and an extraction element disposed outside the polarisation-sensitive reflector, the extraction element comprising: a rear guide surface opposing the front guide surface; and the array of extraction features; the anamorphic near-eye display apparatus is arranged to provide light guided along the extraction waveguide in the first direction with an input linear polarisation state before reaching the polarisation-sensitive reflector; and the optical system further comprises a polarisation conversion retarder disposed between the polarisation-sensitive reflector and the light reversing reflector, wherein the polarisation conversion retarder is arranged to convert a polarisation state of light passing therethrough between a linear polarisation state and a circular polarisation state, and the polarisation conversion retarder and the light reversing reflector are arranged in combination to rotate the input linear polarisation state of the light guided in the first direction so that the light guided in the second direction and output from the polarisation conversion retarder has an orthogonal linear polarisation state that is orthogonal to the input linear polarisation state; the polarisation-sensitive reflector is arranged to reflect light guided in the first direction having the input linear polarisation state and to pass light guided in the second direction having the orthogonal linear polarisation state, so that the front guide surface and the polarisation-sensitive reflector are arranged to guide light in the first direction, and the front guide surface and the rear guide surface are arranged to guide light in the second direction; and the array of extraction features is arranged to extract light guided along the extraction waveguide in the second direction towards an eye of a viewer through the front guide surface, the array of extraction features distributed along the extraction waveguide so as to provide exit pupil expansion in the transverse direction.
According to a ninth aspect of the present disclosure, there is provided a head-worn display apparatus comprising an anamorphic near-eye display apparatus according to any one of the third to eighth aspects and a head-mounting arrangement arranged to mount the anamorphic near-eye display apparatus on a head of a wearer with the anamorphic near-eye display apparatus extending across at least one eye of the wearer.
The optical system of any of the first to ninth aspects of the present disclosure may further comprise: an input waveguide arranged to receive light from the transverse anamorphic component; a partially reflective mirror, the input waveguide arranged to guide light from the transverse anamorphic component to the partially reflective mirror along the input waveguide, and the partially reflective mirror arranged to reflect at least some of that light; an intermediate waveguide arranged to receive at least some of the light reflected by the partially reflective mirror, a lateral anamorphic component having positive optical power in the lateral direction, the intermediate waveguide arranged to guide the light received from the partially reflective mirror to the lateral anamorphic component along the intermediate waveguide in a first direction; a light reversing reflector that is arranged to reflect light that has been guided along the intermediate waveguide in the first direction so that the reflected light is guided along the intermediate waveguide in a second direction opposite to the first direction to the partially reflective mirror, the partially reflective mirror arranged to transmit at least some of that light; and wherein the extraction waveguide is arranged to receive at least some of the light transmitted by the partially reflective mirror that has been guided in the second direction along the intermediate waveguide. Light that is passed by the input waveguide and intermediate waveguide does not pass through light extraction elements. Advantageously stray light may be reduced.
According to a tenth aspect of the present disclosure, there is provided an anamorphic directional illumination device comprising: an illumination system comprising a light source array, the illumination system arranged to output light; and an optical system arranged to direct light from the illumination system, wherein the optical system has an optical axis and has anamorphic properties in a lateral direction and a transverse direction that are perpendicular to each other and perpendicular to the optical axis, wherein the light source array comprises light sources distributed in the lateral direction, and the optical system comprises: a transverse anamorphic component having positive optical power in the transverse direction, wherein the transverse anamorphic component is arranged to receive light from the light source array and the illumination system is arranged so that light output from the transverse anamorphic component is directed in directions that are distributed in the transverse direction; an extraction waveguide arranged to receive light from the transverse anamorphic component; a lateral anamorphic component having positive optical power in the lateral direction, the extraction waveguide arranged to guide light from the transverse anamorphic component to the lateral anamorphic component along the extraction waveguide in a first direction; and a light reversing reflector that is arranged to reflect light that has been guided along the extraction waveguide in the first direction so that the reflected light is guided along the extraction waveguide in a second direction opposite to the first direction, wherein the extraction waveguide comprises at least one extraction feature, the at least one extraction feature arranged to transmit light guided along the extraction waveguide in the first direction and to extract light guided along the extraction waveguide in the second direction, and the lateral anamorphic component comprises: a reflective linear polariser disposed between the light reversing reflector and the at least one extraction feature; and a polarisation conversion retarder disposed between the reflective linear polariser and the light reversing reflector, the polarisation conversion retarder arranged to convert a polarisation state of light passing therethrough between a linear polarisation state and a circular polarisation state. Aberrations of the lateral anamorphic component may be improved. Fidelity of optical cones and field of illumination may be increased. Higher contrast illumination of external scenes may be provided. Reduced glare and increased luminance may be achieved.
According to an eleventh aspect of the present disclosure, there is provided an anamorphic directional illumination device comprising: an illumination system comprising a light source array, the illumination system arranged to output light; and an optical system arranged to direct light from the illumination system, wherein the optical system has an optical axis and has anamorphic properties in a lateral direction and a transverse direction that are perpendicular to each other and perpendicular to the optical axis, wherein the light source array comprises light sources distributed in the lateral direction, and the optical system comprises: a transverse anamorphic component having positive optical power in the transverse direction, wherein the transverse anamorphic component is arranged to receive light from the light source array and the illumination system is arranged so that light output from the transverse anamorphic component is directed in directions that are distributed in the transverse direction; an extraction waveguide arranged to receive light from the transverse anamorphic component; a lateral anamorphic component having positive optical power in the lateral direction, the extraction waveguide arranged to guide light from the transverse anamorphic component to the lateral anamorphic component along the extraction waveguide in a first direction; and a light reversing reflector that is arranged to reflect light that has been guided along the extraction waveguide in the first direction so that the reflected light is guided along the extraction waveguide in a second direction opposite to the first direction, wherein the extraction waveguide comprises at least one extraction feature, the at least one extraction feature arranged to transmit light guided along the extraction waveguide in the first direction and to extract light guided along the extraction waveguide in the second direction, and the transverse anamorphic component comprises: a partially reflective surface; a reflective linear polariser disposed in series with the partially reflective surface, wherein at least one of the partially reflective surface and the reflective linear polariser has positive optical power in the transverse direction; and a polarisation conversion retarder disposed between the partially reflective surface and the reflective linear polariser, the polarisation conversion retarder arranged to convert a polarisation state of light passing therethrough between a linear polarisation state and a circular polarisation state. Advantageously the fidelity of light cones output may be improved. Higher contrast illumination of external scenes may be provided. Reduced glare and increased luminance may be achieved.
According to a twelfth aspect of the present disclosure, there is provided an anamorphic directional illumination device comprising: an illumination system comprising a light source array, the illumination system arranged to output light, and an optical system arranged to direct light from the illumination system, wherein the optical system has an optical axis and has anamorphic properties in a lateral direction and a transverse direction that are perpendicular to each other and perpendicular to the optical axis, wherein the light source array comprises light sources distributed in the lateral direction, and the optical system comprises: a transverse anamorphic component having positive optical power in the transverse direction, wherein the transverse anamorphic component is arranged to receive light from the light source array and the illumination system is arranged so that light output from the transverse anamorphic component is directed in directions that are distributed in the transverse direction; an extraction waveguide arranged to receive light from the transverse anamorphic component; a lateral anamorphic component having positive optical power in the lateral direction, the extraction waveguide arranged to guide light from the transverse anamorphic component to the lateral anamorphic component along the extraction waveguide in a first direction; and a light reversing reflector that is arranged to reflect light that has been guided along the extraction waveguide in the first direction so that the reflected light is guided along the extraction waveguide in a second direction opposite to the first direction, wherein the extraction waveguide comprises at least one extraction feature, the at least one extraction feature arranged to transmit light guided along the extraction waveguide in the first direction and to extract light guided along the extraction waveguide in the second direction, and wherein the lateral anamorphic component comprises a lens formed by at least one surface of an air gap formed in a waveguide. Advantageously the fidelity of light cones output may be improved. Higher contrast illumination of external scenes may be provided. Reduced glare and increased luminance may be achieved.
According to a thirteenth aspect of the present disclosure, there is provided an anamorphic directional illumination device comprising: an illumination system comprising a light source array, the illumination system arranged to output light; and an optical system arranged to direct light from the illumination system, wherein the optical system has an optical axis and has anamorphic properties in a lateral direction and a transverse direction that are perpendicular to each other and perpendicular to the optical axis, wherein the light source array comprises light sources distributed in the lateral direction, and the optical system comprises: a transverse anamorphic component having positive optical power in the transverse direction, wherein the transverse anamorphic component is arranged to receive light from the light source array and the illumination system is arranged so that light output from the transverse anamorphic component is directed in directions that are distributed in the transverse direction; an extraction waveguide arranged to receive light from the transverse anamorphic component; a lateral anamorphic component having positive optical power in the lateral direction, the extraction waveguide arranged to guide light from the transverse anamorphic component to the lateral anamorphic component along the extraction waveguide in a first direction; and a light reversing reflector that is arranged to reflect light that has been guided along the extraction waveguide in the first direction so that the reflected light is guided along the extraction waveguide in a second direction opposite to the first direction, wherein the extraction waveguide comprises at least one extraction feature, the at least one extraction feature arranged to transmit light guided along the extraction waveguide in the first direction and to extract light guided along the extraction waveguide in the second direction, and the lens of the lateral anamorphic component is a Pancharatnam-Berry lens. Advantageously the fidelity of light cones output may be improved. Higher contrast illumination of external scenes may be provided. Reduced glare and increased luminance may be achieved. The compactness of the anamorphic directional illumination device may be improved.
According to a fourteenth aspect of the present disclosure, there is provided an anamorphic directional illumination device comprising: an illumination system comprising a light source array, the illumination system arranged to output light; and an optical system arranged to direct light from the illumination system, wherein the optical system has an optical axis and has anamorphic properties in a lateral direction and a transverse direction that are perpendicular to each other and perpendicular to the optical axis, wherein the light source array comprises light sources distributed in the lateral direction, and the optical system comprises: a transverse anamorphic component having positive optical power in the transverse direction, wherein the transverse anamorphic component is arranged to receive light from the light source array and the illumination system is arranged so that light output from the transverse anamorphic component is directed in directions that are distributed in the transverse direction; an extraction waveguide arranged to receive light from the transverse anamorphic component; a lateral anamorphic component having positive optical power in the lateral direction, the extraction waveguide arranged to guide light from the transverse anamorphic component to the lateral anamorphic component along the extraction waveguide in a first direction; and a light reversing reflector that is arranged to reflect light that has been guided along the extraction waveguide in the first direction so that the reflected light is guided along the extraction waveguide in a second direction opposite to the first direction, wherein the extraction waveguide comprises at least one extraction feature, the at least one extraction feature arranged to transmit light guided along the extraction waveguide in the first direction and to extract light guided along the extraction waveguide in the second direction, and at least one of an input end of the extraction waveguide, the transverse anamorphic component and the light source array has a curvature in the lateral direction that compensates for field curvature of the lateral anamorphic component. Advantageously the fidelity of light cones output may be improved and the field of illumination increased. Higher contrast illumination of external scenes may be provided. Reduced glare and increased luminance may be achieved.
According to a fifteenth aspect of the present disclosure, there is provided an anamorphic directional illumination device comprising: an illumination system comprising a light source array, the illumination system arranged to output light; and an optical system arranged to direct light from the illumination system, wherein the optical system has an optical axis and has anamorphic properties in a lateral direction and a transverse direction that are perpendicular to each other and perpendicular to the optical axis, wherein the light source array comprises light sources distributed in the lateral direction, and the optical system comprises: a transverse anamorphic component having positive optical power in the transverse direction, wherein the transverse anamorphic component is arranged to receive light from the light source array and the illumination system is arranged so that light output from the transverse anamorphic component is directed in directions that are distributed in the transverse direction; an extraction waveguide arranged to receive light from the transverse anamorphic component; a lateral anamorphic component having positive optical power in the lateral direction, the extraction waveguide arranged to guide light from the transverse anamorphic component to the lateral anamorphic component along the extraction waveguide in a first direction; and a light reversing reflector that is arranged to reflect light that has been guided along the extraction waveguide in the first direction so that the reflected light is guided along the extraction waveguide in a second direction opposite to the first direction, wherein the extraction waveguide comprises at least one extraction feature, the at least one extraction feature arranged to transmit light guided along the extraction waveguide in the first direction and to extract light guided along the extraction waveguide in the second direction, and the light source array comprises an array of light sources, wherein each light source comprises sub-light sources of plural colour components and a pitch of the sub-light sources of each colour component across the light sources in the lateral direction varies between the colour components in a manner that compensates for chromatic aberration between light of the colour components. Advantageously colouration of the output light cones may be reduced. Image fidelity may be increased and field of illumination improved.
According to a sixteenth aspect of the present disclosure, there is provided a vehicle external light apparatus comprising an anamorphic directional illumination device according to any one of the tenth to fifteenth aspects. An array of illumination light cones for illumination of a road scene may be provided. The light cones may provide control of regions of the road scene that are illuminated. Illuminance may be reduced in the region of oncoming vehicles to reduce glare to oncoming drivers. Illuminance to road hazards may be increased in regions that are not around the location of drivers. Improved driver safety may be achieved.
Any of the aspects of the present disclosure may be applied in any combination.
Embodiments of the present disclosure may be used in a variety of optical systems. The embodiments may include or work with a variety of projectors, projection systems, optical components, displays, microdisplays, computer systems, processors, self-contained projector systems, visual and/or audio-visual systems and electrical and/or optical devices. Aspects of the present disclosure may be used with practically any apparatus related to optical and electrical devices, optical systems, presentation systems or any apparatus that may contain any type of optical system. Accordingly, embodiments of the present disclosure may be employed in optical systems, devices used in visual and/or optical presentations, visual peripherals and so on and in a number of computing environments and automotive environments.
Before proceeding to the disclosed embodiments in detail, it should be understood that the disclosure is not limited in its application or creation to the details of the particular arrangements shown, because the disclosure is capable of other embodiments. Moreover, aspects of the disclosure may be set forth in different combinations and arrangements to define embodiments unique in their own right. Also, the terminology used herein is for the purpose of description and not of limitation.
These and other advantages and features of the present disclosure will become apparent to those of ordinary skill in the art upon reading this disclosure in its entirety.
Embodiments are illustrated by way of example in the accompanying FIGURES, in which like reference numbers indicate similar parts, and in which:
Terms related to optical retarders for the purposes of the present disclosure will now be described.
In a layer comprising a uniaxial birefringent material there is a direction governing the optical anisotropy whereas all directions perpendicular to it (or at a given angle to it) have equivalent birefringence.
The optical axis of an optical retarder refers to the direction of propagation of a light ray in the uniaxial birefringent material in which no birefringence is experienced. This is different from the optical axis of an optical system which may for example be parallel to a line of symmetry or normal to a display surface along which a principal ray propagates.
For light propagating in a direction orthogonal to the optical axis, the optical axis is the slow axis when linearly polarized light with an electric vector direction parallel to the slow axis travels at the slowest speed. The slow axis direction is the direction with the highest refractive index at the design wavelength. Similarly the fast axis direction is the direction with the lowest refractive index at the design wavelength.
For positive dielectric anisotropy uniaxial birefringent materials the slow axis direction is the extraordinary axis of the birefringent material. For negative dielectric anisotropy uniaxial birefringent materials the fast axis direction is the extraordinary axis of the birefringent material.
The terms half a wavelength and quarter a wavelength refer to the operation of a retarder for a design wavelength λ0 that may typically be between 500 nm and 570 nm. In the present illustrative embodiments exemplary retardance values are provided for a wavelength of 550 nm unless otherwise specified.
The retarder provides a phase shift between two perpendicular polarization components of the light wave incident thereon and is characterized by the amount of relative phase, Γ, that it imparts on the two polarization components; which is related to the birefringence Δn and the thickness d of the retarder with retardance Δn. d by:
Γ=2·π·Δn·d/λ0 eqn. 1
In eqn. 1, Δn is defined as the difference between the extraordinary and the ordinary index of refraction, i.e.
Δn=ne−no eqn. 2
For a half-wave retarder, the relationship between d, Δn, and λo is chosen so that the phase shift between polarization components is Γ=π. For a quarter-wave retarder, the relationship between d. An, and λo is chosen so that the phase shift between polarization components is Γ=π/2.
Some aspects of the propagation of light rays through a transparent retarder between a pair of polarisers will now be described.
The state of polarisation (SOP) of a light ray is described by the relative amplitude and phase shift between any two orthogonal polarization components. Transparent retarders do not alter the relative amplitudes of these orthogonal polarisation components but act only on their relative phase. Providing a net phase shift between the orthogonal polarisation components alters the SOP whereas maintaining net relative phase preserves the SOP. In the current description, the SOP may be termed the polarisation state.
A linear SOP has a polarisation component with a non-zero amplitude and an orthogonal polarisation component which has zero amplitude. A p-polarisation state is a linear polarisation state that lies within the plane of incidence of a ray comprising the p-polarisation state and a s-polarisation state is a linear polarisation state that lies orthogonal to the plane of incidence of a ray comprising the p-polarisation state. For a linearly polarised SOP incident onto a retarder, the relative phase r is determined by the angle between the optical axis of the retarder and the direction of the polarisation component.
A linear polariser transmits a unique linear SOP that has a linear polarisation component parallel to the electric vector transmission direction of the linear polariser and attenuates light with a different SOP. The term “electric vector transmission direction” refers to a non-directional axis of the polariser parallel to which the electric vector of incident light is transmitted, even though the transmitted “electric vector” always has an instantaneous direction. The term “direction” is commonly used to describe this axis.
Absorbing polarisers are polarisers that absorb one polarisation component of incident light and transmit a second orthogonal polarisation component. Examples of absorbing linear polarisers are dichroic polarisers.
Reflective polarisers are polarisers that reflect one polarisation component of incident light and transmit a second orthogonal polarisation component. Examples of reflective polarisers that are linear polarisers are multilayer polymeric film stacks such as DBEF™ or APF™ from 3M Corporation, or wire grid polarisers such as ProFlux™ from Moxtek. Reflective linear polarisers may further comprise cholesteric reflective materials and a quarter wave retarder arranged in series.
A retarder arranged between a linear polariser and a parallel linear analysing polariser that introduces no relative net phase shift provides full transmission of the light other than residual absorption within the linear polariser.
A retarder that provides a relative net phase shift between orthogonal polarisation components changes the SOP and provides attenuation at the analysing polariser.
Achromatic retarders may be provided wherein the material of the retarder is provided with a retardance Δn. d that varies with wavelength λ as
Δn·d/λ=κ eqn. 3
where κ is substantially a constant.
Examples of suitable materials include modified polycarbonates from Teijin Films. Achromatic retarders may be provided in the present embodiments to advantageously minimise colour changes between polar angular viewing directions which have low luminance reduction and polar angular viewing directions which have increased luminance reductions as will be described below.
In the present disclosure an ‘A-plate’ refers to an optical retarder utilizing a layer of birefringent material with its optical axis parallel to the plane of the layer. The optical axis direction of the optical retarder is arranged to provide retardance in correspondence to the SOP of the incident light ray, for example to convert linearly polarised light to circularly polarised light, or to convert circularly polarised light to linearly polarised light.
The structure and operation of various anamorphic near-eye display apparatuses will now be described. In this description, common elements have common reference numerals. It is noted that the disclosure relating to any element applies mutatis mutandi to each device in which the same or corresponding element is provided. Accordingly, for brevity such disclosure is not repeated. Similarly, the various features of any of the following examples may be combined together in any combination.
It would be desirable to provide an anamorphic near-eye display apparatus 100 with a thin form factor, large freedom of movement, high resolution, high brightness and wide field of view. An anamorphic near-eye display apparatus 100 will now be described.
The anamorphic near-eye display apparatus 100 comprises an illumination system 240 arranged to provide output light comprising illumination from a spatial light modulator 48 and an optical system 250 arranged to direct light from the illumination system 240 to the eye 45 of an observer 47. The illumination system 240 is arranged to output light rays 400 including illustrative light rays 401, 402 that are input into the optical system 250.
In operation, it is desirable that the spatial pixel data provided on the spatial light modulator 48 is directed to the pupil 44 of the eye 45 as angular pixel data. The lens of the observer's eye 45 relays the angular spatial data to spatial pixel data at the retina 46 of the eye 45 such that an image is provided by the anamorphic near-eye display apparatus 100 to the observer 47.
The pupil 44 is located in a spatial volume near to the anamorphic near-eye display apparatus 100 commonly referred to as the exit pupil 40, or eyebox. When the pupil 44 is located within the exit pupil 40, the observer 47 is provided with a full image without missing parts of the image, that is the image does not appear to be vignetted at the observer's retina 46. The shape of the exit pupil 40 is determined at least by the anamorphic imaging properties of the anamorphic near-eye display apparatus and the respective aberrations of the anamorphic optical system. The exit pupil 40 at a nominal eye relief distance eR may have dimension eL in the lateral direction 195 and dimension eT in the transverse direction 197. The maximum eye relief distance eRmax refers to the maximum distance of the pupil 44 from the anamorphic near-eye display apparatus 100 wherein no image vignetting is present. In the present embodiment, increasing the size of the exit pupil 40 refers to increasing the dimensions eL, eT. Increased exit pupil 40 achieves an increased viewer freedom and an increase in eRmax as will be described further hereinbelow.
The spatial light modulator 48 comprises pixels 222 distributed at least in the lateral direction 195 as will be described further hereinbelow, for example in
The anamorphic near-eye display apparatus 100 further comprises a control system 500 arranged to operate the illumination system 240 to provide light that is spatially modulated in accordance with image data representing an image.
The optical system 250 comprises a transverse lens 61 that forms a transverse anamorphic component 60 in the embodiment of
In the present disclosure, the term lens most generally refers to a single lens element or most commonly a compound lens (group of lens elements) as will be described hereinbelow in
The transverse lens 61 in the embodiment of
Mathematically expressed, for any location within the anamorphic near-eye display apparatus 100, the optical axis direction 199 may be referred to as the O unit vector, the transverse direction 197 may be referred to as the T unit vector and the lateral direction 195 may be referred to as the L unit vector wherein the optical axis direction 199 is the crossed product of the transverse direction 197 and the lateral direction 195:
O=T×L eqn.4
Various surfaces of the anamorphic near-eye display apparatus 100 transform or replicate the optical axis direction 199; however, for any given ray the expression of eqn. 4 may be applied.
The optical system 250 further comprises an extraction waveguide 1 arranged to guide light rays 400 in cone 491 from the transverse anamorphic component 60 to a lateral anamorphic component 110 along the extraction waveguide 1 in a first direction 191. The extraction waveguide 1 has opposing rear and front guide surfaces 6, 8 that are planar and parallel. The extraction waveguide 1 further has an input end 2 extending in the lateral and transverse directions 195(60), 197(60), the extraction waveguide 1 being arranged to receive light 400 from the illumination system 240 through the input end 2. The input end 2 extends in the lateral direction 195 between edges 22, 24 of the extraction waveguide 1, and extends in the transverse direction between opposing rear and front guide surfaces 6, 8 of the extraction waveguide 1.
The optical system 250 further comprises a light reversing reflector 140 arranged to reflect the light rays 400 in light cones 491 that have been guided along the extraction waveguide 1 so that the reflected light rays 400 in light cone 493 is guided along the extraction waveguide 1 in a second direction 193 opposite to the first direction 191 and so that reflected cone 493 is guided back through the extraction waveguide 1.
In the embodiment of
The extraction waveguide 1 comprises an array of extraction reflectors 170 disposed internally within the extraction waveguide 1, the extraction reflectors 170 being arranged to transmit light guided 400 along the extraction waveguide 1 in the first direction 191 and to extract light guided along the extraction waveguide 1 in the second direction 193 towards an eye 45 of a viewer. The array of extraction reflectors 170 are distributed along the extraction waveguide 1 so as to provide exit pupil expansion.
The extraction reflectors 170 are an example of reflective extraction features 169 and each comprises a set of layers that are reflective layers as will be described further hereinbelow. In other embodiments, such as described in
The extraction waveguide 1 is further arranged to receive light cone 493 from the transverse anamorphic component 60 and the lateral anamorphic component 110; and comprises an array of extraction reflectors 170A-E disposed internally within the extraction waveguide 1. The extraction reflectors 170 are inclined with respect to the first and second directions 191, 193 along the optical axis 199 of the extraction waveguide 1. The extraction reflectors 170 extend partially across the extraction waveguide 1 between the opposing rear and front guide surfaces 6, 8.
The extraction waveguide 1 comprises intermediate surfaces 172 extending along the extraction waveguide between adjacent pairs of extraction reflectors 170. In the embodiment of
The extraction reflectors 170 are arranged to transmit at least some of light cone 491 guided along the extraction waveguide 1 in the first direction 191 and to extract at least some of light cone 493 guided back along the extraction waveguide 1 in the second direction 193 towards an eye 45 of a viewer 47 as will be described further hereinbelow.
The coordinate system and principle of operation of the anamorphic near-eye display apparatus 100 will now be further described. The optical system 250 has an optical axis 199 and has anamorphic properties in a lateral direction 195 and in a transverse direction 197 that are perpendicular to each other and perpendicular to the optical axis 199.
Further features of the arrangement of
The optical system 250 may comprise an input linear polariser 70 disposed between the spatial light modulator 48 and the extraction reflectors 170 of the extraction waveguide 1. In
Further the optical system 250 may comprise a polarisation conversion retarder 72 disposed between the light reversing reflector 140 and the array of extraction reflectors 170. Polarisation conversion retarder 72 may be an A-plate with an optical axis direction arranged to convert linearly polarised light to circularly polarised light and circularly polarised light to linearly polarised light. In the embodiment of
The operation of the input linear polariser 70 and polarisation conversion retarder 72 will be described further with respect to at least
In operation extraction waveguide 1 is arranged to guide light rays 400 between the opposing rear and front guide surfaces 6, 8 as illustrated by the zig-zag paths of guided rays 401, 402.
In the first direction 191 at least some of the light rays 400 propagate through the extraction reflectors 170. Waveguide 1 further comprises a reflective end 4 arranged to receive the guided light rays 401, 402 from the input end 2. The lateral anamorphic component 110 comprises the reflective end 4 of the extraction waveguide 1 with a reflective material provided on the reflective end 4. The reflective material may be a reflective film such as ESR™ from 3M or may be an evaporated or sputtered metal material. In the embodiment of
For light cone 493 propagating in the second direction 193, the extraction reflectors 170 are oriented to extract light guided back along the extraction waveguide 1 through the second light guiding surface 8 and towards the pupil 44 of eye 45 arranged in eyebox 40.
The operation of the anamorphic near-eye display apparatus 100 as an augmented reality display will now be further described.
The extraction waveguide 1 is transmissive to light that passes through the intermediate surfaces 172 such that on-axis real image point 31 on a real-world object 30 is directly viewed through the extraction waveguide 1 by light ray 32. Similarly virtual image 34 with aligned on-axis virtual pixel 36 is desirably viewed with virtual ray 37. Such virtual ray 37 is provided by on-axis light ray 401 after reflection from extraction reflector 170C to the pupil 44 of eye 45. Similarly off-axis virtual ray 39 for viewing of virtual pixel 38 is provided by off-axis ray 402 after reflection from the extraction reflector 170D. An augmented reality display with advantageously high transmission of external light rays 32 may be provided.
The imaging properties of the anamorphic near-eye display apparatus 100 will now be further described using an unfolded schematic representation wherein said transformations of coordinates are removed for purposes of explanation.
For illustrative purposes, in
The observer perceives a magnified virtual image with the optical system 250 arranged between the virtual image 34 and the eye 45, with the same field of view ϕ in each of lateral and transverse directions 195, 197.
In the anamorphic near-eye display apparatus 100 of the present embodiments, the distance fT between the first principal plane of the transverse anamorphic component 60 of the optical system 250 is different to the distance fL between the first principal plane of the lateral anamorphic component 110 of the optical system 250. Similarly, for a square output field of view (ϕT is the same as ϕL), the separation DT of pixels 222T, 222B in the transverse direction is different to the separation DL of pixels 222R, 222L in the lateral direction 195.
In the present description, the lateral angular magnification ML provided by the lateral anamorphic component 110 of the optical system 250 may be given as
M
L
=ϕp
L
/P
L eqn. 5
M
T
=ϕp
L
/P
T eqn. 6
where ϕpL is the angular size of a virtual pixel 36 seen by the eye in the lateral direction 195, PL is the pixel pitch in the lateral direction 195, ϕpT is the angular size of a virtual pixel 36 seen by the eye in the transverse direction 197, and PT is the pixel pitch in the transverse direction 197. In the case that the angular virtual pixels 36 are square, then ϕpL and ϕpT are equal and the angular magnification provided by the lateral anamorphic component 110 may be given as:
M
L
=M
T
*P
T
/P
L eqn. 7
The angular magnification ML, MT of the lateral and transverse anamorphic optical elements 110, 60 is proportional to the respective optical power KL, KT of said elements 60, 110. The spatial light modulator 48 may comprise pixels 222 having pitches PL, PT in the lateral and transverse directions 195, 197 with a ratio PL/PT that is the same as KT/KL, being the inverse of the ratio of optical powers of the lateral and transverse anamorphic optical elements 110, 60.
The output coordinate system is illustrated in
The row 221Tc of pixels 222 through the central pixel 225 that is extended in the lateral direction 195 is output as fan 493L of rays, each ray representing the angle at which a virtual pixel 38 is provided to the pupil 44 across the lateral direction 195.
The column 221Lc of pixels 222 through the central pixel 225 that is extended in the transverse direction 197 is output as fan 493T of rays, each ray representing the angle at which a virtual pixel 38 is provided to the eye 45 across the transverse direction 197.
For a pixel 227 arranged in a quadrant of the spatial light modulator 48 an output ray 427 is provided to the pupil 44 that is imaged first by the transverse anamorphic component 60 and then by the lateral anamorphic component 110.
Illustrative imaging properties of the anamorphic near-eye display apparatus 100 of
Points with 0 degrees lateral field of view lie in the transverse light cone 493L, while points with 0 degrees transverse field of view lie in the transverse light cone 493T. The relative aberrations at various image points are illustrated by blur point spread functions 452.
The lateral size 454L and transverse size 454T of the blur PSF 452 is determined by aberrations of the optical system 250. The elliptical blur PSF 452 is an illustrative profile of the relative blurring from a point at a pixel 227 on the spatial light modulator 48 when output as an angular cone to the eye 45 and thus represents the relative PSF size and location at the retina 46 of the eye 45 in the lateral and transverse directions 195, 197.
For illustrative purposes the blur point spread function (PSF) 452 is illustrated in
The sizes 454TR, 454LR of the blur PSF 452R for red pixels 222R may be different to the sizes 454TB, 454LB for the blur PSF 452B for blue pixels 222B. Further the centre of gravity of the blur PSF 452B may be displaced in lateral and transverse directions 195, 197 by colour blur 455L, 455T respectively.
Chromatic aberration for an illustrative anamorphic near-eye display apparatus 100 is described further in
Illustrative arrangements of pixels 222 of the spatially multiplexed spatial light modulator 48 will now be described.
The spatial light modulator 48 may be a transmissive spatial light modulator 48 such as an LCD as illustrated in
In
White pixels 222 comprising red, green and blue sub-pixels 222R, 222G, 222B are provided spatially separated in the lateral direction 195 and the sub-pixels 222R, 222G, 222B are elongate with a pitch PL in the lateral direction that is greater than the pitch PT in the transverse direction 197.
Considering
The pixels 222 are arranged as columns 221L, wherein the columns 221L are distributed in the lateral direction 195, and the pixels along the columns 221L are distributed in the transverse direction 197; and the pixels 222 are further arranged as rows 221T, wherein the rows 221T are distributed in the transverse direction 197, and the pixels along the rows 221T are distributed in the lateral direction 195.
In
In the alternative embodiment of
The sub-pixels 222R, 222G, 222B may be provided by white light emission and patterned colour filters, or may be provided by direct emission of respective coloured light. The present embodiments comprise sub-pixel 222 pitch PL that is larger than other known arrangements comprising a symmetric input lens for thin waveguides.
In the alternative embodiment of
The spatial light modulator 48 may be used for monochromatic illumination. In alternative embodiments wide colour gamut imagery may be provided by time sequential illumination, for example by red, green and blue illumination in synchronisation with red, green and blue image data provided on the spatial light modulator 48. Advantageously image resolution may be increased.
In comparison to non-anamorphic image projectors in which equal angular magnification is provided between the lateral direction 195 and transverse direction 197, the present embodiments provide pixel pitch PL that is substantially increased in size for a given angular image size and magnification in the transverse direction 197. Such increased size may advantageously achieve increased brightness, increased efficiency and reduced alignment tolerances for the spatial light modulator 48 and illumination system 240.
In colour filter type spatial light modulators 48, the size of colour filters may be increased. Advantageously cost and complexity of colour filters may be reduced. The aperture ratio of the pixels 222 may be increased. In direct emission displays the size of the emitting region may be increased. Advantageously cost and complexity of fabricating the pixels may be reduced and brightness increased. In inorganic micro-LED spatial light modulators 48, efficiency loss due to recombination losses at the edges of pixels may be reduced and system efficiency and brightness advantageously increased.
Input of light into the anamorphic near-eye display apparatus 100 of
The input of transverse light cones 491T into the extraction waveguide 1 will now be described with reference to
In the illustrative embodiment of
Spatial light modulator 48 and transverse anamorphic component 60 formed by the transverse lens 61 are inclined at the angle δ with respect to the normal to the rear and front guide surfaces 6, 8. The direction of the optical axis 199(60) through the transverse anamorphic component 60 is thus inclined with respect to the first and second directions 191, 193 along the extraction waveguide 1. The optical axis 199(60) direction is typically parallel to the surface normal of the input end 2, such that the optical axis direction 199(60) is inclined at the angle 90-δ with respect to the first and second direction 191, 193. Referring to
The optical system 250 further comprises a tapered surface 18 that is a surface inclined at angle δ provided near the input end 2 to direct light bundles in the transverse direction 197 from the transverse anamorphic component 60 into the extraction waveguide 1 at desirable angles of propagation. The tapered surface 18 is arranged between the input end 2 and the light guiding surface 8, with surface normal direction inclined at an angle δ with respect to the surface normal to the light guiding surface 8. In alternative embodiments, the tapered surface 18 may be arranged on the first light guiding surface 6.
TABLE 1 shows an illustrative embodiment of the geometry of the arrangement of
Central pixel 222C provides illumination to the transverse anamorphic component 60 with illustrative light rays 460CA, 460CB. Light ray 460CA is input through the input end 2 without deflection and is directed to just miss the interface 19 of the tapered surface 18 and the second light guiding surface 8, and is thus undeflected. Light ray 460CB is however incident on the region of the first light guiding surface 6 opposite the tapered surface 18 and is reflected by total internal reflection to the same interface 19, at which it is just totally internally reflected, such that the rays 460CA, 460CB overlap and are guided in the first direction 191 along the extraction waveguide 1.
The extraction reflectors 170 desirably have a surface normal direction nR that is inclined with respect to the direction 191 along the waveguide by an angle α′ (which in
In alternative embodiments, the extraction reflectors may have an angle α′ that is in the range 50 to 70 degrees, preferably have an angle in the range 55 to 65 degrees and most preferably have an angle in the range 57.5 degrees to 62.5 degrees. Such arrangement directs light ray 460C through the light guiding surface 8 when the ray has not reflected from the intermediate surface 172 after reflection from the light guiding surface 8.
The embodiment of TABLE 1 illustrates a design for refractive index of 1.5. The refractive index of the extraction waveguide 1 may be increased, for example to a refractive index of 1.7 or greater. Advantageously the size of the light cone ϕT may be increased and a larger angular image seen in the transverse direction.
The outer pixels 222T, 222B in the lateral direction 195(48) define the outer limit of light cones 491TA, 491TB that propagate at angles T either side of rays 460CA, 460CB. The tapered surface 18 is provided such that the whole of the light cone 491TA is not deflected near to the input end 2, advantageously achieving reduced cross-talk and high efficiency. After the light cones 491TA, 491TB pass the interface 19, then they recombine to propagate along the extraction waveguide 1.
The propagation of transverse light cones 491T along the extraction waveguide 1 in the first direction 191 will now be described with reference to
Considering
The direction of the optical axis 199(60) through the transverse anamorphic component 60 is inclined at angle δ that is inclined at angle 90-δ to the first direction 191 along the extraction waveguide 1.
After the interface 19, the light cone 491T is incident on the first light guiding surface 6 with an angle of incidence δ and is reflected by total internal reflection such that a replicated light cone 491Tf is provided propagating along the extraction waveguide 1 in the direction 191.
The reflected light cones 493T, 493Tf propagate along the second direction 193 with angle r about optical axes 199(60) and 199f(60). Corresponding transverse directions 197(60), 197f(60) are also indicated.
Both cones 493T, 493Tf comprise image data that between the cones 493T, 493Tf is flipped about the direction 191 and thus provides degeneracy of ray directions for a given pixel 222 on the spatial light modulator 48. It is desirable to remove such degeneracy so that only one of the cones 493T, 493Tf is extracted and a secondary image is not directed to the pupil 44 of the eye 45.
Central output light ray 37 propagates by total internal reflection of opposing surfaces 6, 8 until it is incident on an intermediate surface 172 at which at least some light is reflected, and then at extraction reflector 170 at which at least some light is further reflected as will be described further hereinbelow such that light cone 493T is preferentially directed towards the second light guiding surface 8. After refraction at the light guiding surface 8, light in the cone 495T is extracted towards the eye 45, with a cone angle that has increased size compared to the cone 493T.
The extraction reflectors 170A-E are inclined at the same angle, a such that for each of the light extraction reflectors 170A-E of
By way of comparison, the light cone 493Tf around central light rays 460C which are incident on the surface 8 and then are directly incident on extraction reflector 170 without first reflecting from the intermediate surface 72 have an angle of incident that is different to the angle of incident 6. The difference in angle of incidence provides for preferential transmission through the extraction reflector 170, and light cone 493Tf is not directed towards the eye 45. Degeneracy is reduced or removed and image cross-talk advantageously reduced.
The inclined input end 2 and inclined transverse anamorphic component 60 thus provide cones 493T, 493Tf that are not overlapping with one of said cones preferentially extracted towards the eye 45 and the other cone preferentially retained within the extraction waveguide. The tilted input end 2 and tilted transverse anamorphic component 60 thus advantageously achieve a single image visible to the eye 45 and double images are minimised. In some of the illustrative embodiments hereinbelow, the surface normal of the input end 2 is not inclined to the first and second directions 191, 193, however that is to simplify the illustrations hereinbelow rather than a typical arrangement.
In alternative embodiments (not shown), the central output ray 37 may be inclined to the surface normal to the light guiding surface 8, for example to adjust the angular location of the centre of the field of view of the extracted light cone 495T.
In the alternative embodiment of
In the alternative embodiment of
The extraction reflectors may have a surface normal direction n that may be inclined with respect to the direction along the waveguide 193 by an angle α′ in the range 20 to 40 degrees, preferably by an angle α′ in the range 25 to 35 degrees and most preferably by an angle α′ in the range 27.5 degrees to 32.5 degrees. Said desirable surface normal n directions may reduce the visibility of a flipped image in the transverse direction 197. Such reduction of visibility is for example as illustrated in
Exit pupil 40 expansion in the transverse direction 197 will now be described.
The array of extraction reflectors 170 are distributed along the extraction waveguide 1 so as to provide exit pupil 40 expansion that is increasing the size eT of the eyebox 40 in the transverse direction 197 as will now be described.
The extraction reflectors 170 extend partially across the extraction waveguide 1 between opposing rear and front guide surfaces 6, 8 of the extraction waveguide 1 with successively shifted positions. The successively shifted positions are arranged along the waveguide in the direction 191. In other words, in the transverse direction 197 the extraction reflectors 170 extend partially across the extraction waveguide 1 with successively shifted positions.
Considering
Considering
Considering
As will be described in
The imaging properties of the anamorphic near-eye display apparatus 100 in the lateral direction 195 will now be considered further.
In the embodiment of
The pupil 44 sees the off-axis rays from pixel 222L at the edge of the spatial light modulator 48 after reflection from a region 478L of the lateral anamorphic component 110, which is the reflective end 4 of the extraction waveguide 1. While the lateral anamorphic component 110 in its entirety is a relatively fast optical element and thus prone to aberrations, particularly from its edges, the region 478 of the lateral anamorphic component 110 that is directing light into the pupil 44 for any one eye 45 location is small, and thus aberrations from the lateral anamorphic component 110 are correspondingly reduced. Considering
In the embodiment of
Light rays 470, 471 are directed from a central pixel 222M across the lateral direction 195 of the spatial light modulator 48 and transmitted through the transverse anamorphic component 60 formed by the transverse lens 61 without optical power in the lateral direction 195 and into the extraction waveguide 1. Said light rays 470, 471 propagate in the first direction 191 of the extraction waveguide 1 to the light reversing reflector 140 which provides positive optical power in the lateral direction 195 by means of the reflective end 4 which provides the lateral anamorphic component 110.
Such light rays 470, 471 are reflected in the extraction waveguide 1 in the second direction 193 from the region 478MA of the lateral anamorphic component 110 and at the extraction reflector 170A is reflected away from the plane of the extraction waveguide 1 to the pupil 44 of the eye 45A at the viewing distance eg. The eye 45 collects the rays 470, 471 and directs them to the same point on the retina 46 to provide a virtual pixel location as described elsewhere herein.
Similarly for off-axis pixel 222L offset in the lateral direction 195(48), at the edge of the spatial light modulator 48 provides rays 472, 473 that are directed into the extraction waveguide 1, reflected at region 478LA of the lateral anamorphic component 110 and reflected by extraction reflector 170A to the eye 45A to provide an off-axis image point in the lateral direction 195(44) on the retina 46.
The lateral anamorphic component 110 has a positive optical power that provides collimated optical rays from each image point 222L, 222M in the lateral direction 195. In this manner the lateral distribution of field points are provided across the retina 46 by means of the optical power of the lateral anamorphic component 110, while the transverse anamorphic component 60 has optical power to provide the transverse distribution of field points across the retina 46. At diagonal field angles, such as illustrated in
Polarised light propagation in the illustrative embodiment of
As described above with respect to
In the alternative embodiment of
Output light ray 37 is guided in the first direction 191 by total internal reflection at opposing rear and front guide surfaces 6, 8 towards the lateral anamorphic component 110 comprising light reversing reflector 140, which in the embodiment of
As will be described further hereinbelow, the p-polarised state 902 is at least in part and preferably preferentially transmitted through the extraction reflectors 170 and intermediate surfaces 172.
The polarisation conversion retarder 72 is provided between the extraction reflectors 170A-E and the light reversing reflector 140. Polarised light ray 37 is converted to a left-hand circular polarisation state 922 and a n phase shift occurring on reflection at the light reversing reflector 140 provides a reflected right-hand circular polarisation state 924. The polarisation conversion retarder 72 outputs s-polarised polarisation state 904 that propagates along light ray 37 back up the extraction waveguide 1 in the second direction 193.
The polarisation conversion retarder 72 most generally serves to provide the polarisation modification to provide conversion from polarisation state 902 to polarisation state 904 for light ray 37. The polarisation conversion retarder 72 may have a retardance of a quarter wavelength at a wavelength of 550 nm or may be tuned for another visible wavelength for example to match the peak luminance of a monochrome display. The retardance of the polarisation conversion retarder 72 may be different to a quarter wavelength, but selected to provide the same effect. For example, the polarisation conversion retarder 72 may have a retardance of three quarter wavelengths or five quarter wavelengths, for example. The polarisation conversion retarder 72 may comprise a stack of retarders to provide desirable phase modification over an increased spectral range, for example with a Pancharatnam retarder stack (which is different to the Pancharatnam-Berry lens described hereinbelow). Advantageously colour uniformity may be increased. The polarisation conversion retarder 72 may be provided with additional retarder layers to increase the field of view of the quarter wave retarder function, to achieve increased uniformity across the field of view of observation.
In
As will be described further herein below, the s-polarised state 904 is preferentially reflected by the extraction reflectors 170 and intermediate surfaces 172 and output towards the pupil 44 of the eye 45.
Unpolarised light from real-world objects 30 is directed through the extraction waveguide 1. Optional polariser 90 with p-polarised electric vector transmission direction 90 may be provided that transmits the linear polarisation state 920 and may be arranged so that the extraction waveguide 1 is arranged between the object 30 and the eye 45. Polariser 90 may provide a sunglasses function and reduce background object luminance in comparison to the luminance of the anamorphic near-eye display apparatus 100. Further light rays 32 may be preferentially transmitted through the extraction reflectors 170 rather than reflected at the extraction reflectors 170. Advantageously image contrast of overlayed virtual images may be increased and double imaging reduced.
It would be desirable to improve aberrations from the lateral anamorphic component 110.
The alternative embodiment of
In the alternative embodiment of
The reflective linear polariser 99 is arranged between waveguide parts 911A, 911B and the polarisation conversion retarder 89 is arranged between waveguide parts 911B, 911C. In alternative embodiments such as illustrated in
In
Considering light ray 489, input linear polariser 70 provides p-polarisation state 902 in the waveguide 1. Light ray 489 is transmitted by reflective linear polariser 99. The polarisation conversion retarder 89 has a retardance of a quarter wavelength at a wavelength of visible light; that is the polarisation conversion retarder 89 may be a quarter wave retardation at a visible wavelength such as 550 nm and may comprise a stack of composite retarders arranged to achieve the operation of a quarter wave retarder over an increased spectral band, for example comprising a Pancharatnam stack. The retardance of the polarisation conversion retarder 89 may be different to a quarter wavelength, but selected to provide the same effect. For example, the polarisation conversion retarder 89 may have a retardance of three quarter wavelengths or five quarter wavelengths, for example.
The optical system 250 further comprises an input linear polariser 70 disposed between the spatial light modulator 48 and the array of extraction reflectors 174A-C, wherein the input linear polariser 70 and the reflective linear polariser 99 of the lateral anamorphic component 110 are arranged to pass a common polarisation state.
Reflective linear polariser 99 may be a wire grid polariser or a multilayer polariser film such as 3M APF reflective polariser and may be bonded between parts 911A, 911B of the extraction waveguide 1.
The polarisation conversion retarder 89 of
The light ray 489 is thus incident twice onto the light reversing reflector 140. Such an arrangement may reduce the sag of the light reversing reflector 140 in comparison to the light reversing reflector 141 that would be used if the reflective linear polariser 99 and polarisation conversion retarder 89 were omitted. Aberrations of the optical system may be reduced and MTF increased. Further the optical power is achromatic, minimising colour blur. Advantageously the eye 45 may see reduced image blur for off-axis viewing directions. Field of view may be increased for high image quality.
In alternative embodiments to those described elsewhere herein, the polarisation state 902 may be provided by another polarisation state such as a linearly polarised s-polarisation state or a circular polarisation state for example. Corresponding polarisation states that propagate through the system may be provided, to achieve a similar operation. The polarisation state 902 may be provided to achieve desirably low glare for light exiting from the waveguide 1 away from the eye 45 of the viewer 47 and efficient reflection from reflective extraction reflectors 174 after reflection from the light reversing reflector 140. Further improvement of aberrations as described hereinbelow may be achieved.
In comparison to the embodiment of
Further, the reflective linear polariser 99 may be provided in manufacture by means of curving the surface of the reflective linear polariser 99 about a single axis. Distortions of the reflective linear polariser 99 may be advantageously reduced.
In the alternative embodiment of
Further the reflective linear polariser 99 may have a profile that has an aspheric shape to advantageously achieve improved aberrations.
In the alternative embodiment of
The alternative embodiment of
The embodiments of
In the alternative embodiment of
In
The optical system 250 comprises an input linear polariser 70 disposed between the spatial light modulator 48 and the array of extraction reflectors 170 and polarisation conversion retarder 89 is curved in the lateral direction 195.
In
Considering the propagation of polarisation states along the ray 489 in
Half of the light is transmitted through the reflective linear polariser 99 and polarisation states 991, 992, 993, 994, 995, 996, 997 are provided by the various reflections and passes through polarisation conversion retarder 89 as described for
As described elsewhere herein, the polarisation conversion retarder 71 may be arranged to reflect the residual transmitted light to be absorbed at input linear polariser 70. Advantageously visibility of the unextracted light is reduced.
In the alternative embodiment of
In the regions 178A, 178B, there may for example be some residual birefringence in the bulk material of the extraction waveguide 1 that may cause some polarisation state modification to an input linear polarisation state. The arrangement of
Further the polarisation conversion retarder 89 is curved and arranged on the light reversing reflector 140. Advantageously complexity of fabrication is reduced.
By way of comparison with
Polarisation control retarder 87 has a retardance and optical axis direction 887 arranged to provide a linear polarisation state 971 inclined at 45 degrees to the electric vector transmission direction of the reflective linear polariser 99 and absorbing polariser 85. Half of the light is transmitted as polarisation state 992 which as described in
The polarisation control retarder 87 may have a half wave retardance at a visible wavelength such as 550 nm and may comprise a stack of composite retarders arranged to achieve the operation of a half wave retarder over an increased spectral band, for example comprising a Pancharatnam stack.
It may be desirable to improve the aberrations and/or reduce the size of the transverse anamorphic component 60.
Various alternative arrangements of extraction features will now be described. In general the extraction features from different embodiments are interchangeable. That is, the extraction features provided in any of the embodiments described above may be replaced by any of the alternative arrangements of extraction features described elsewhere herein, including the examples below.
The extraction features 169 may comprise extraction reflectors 170 that extend partially across the extraction waveguide 1 between front and rear guide surfaces 8, 6 of the extraction waveguide 1, for example as illustrated in
In another alternative, the extraction waveguide 1 may have a front guide surface 8 and a rear guide surface 6, and the rear guide surface 6 comprises extraction facets 12, 172 that are the extraction features 169, each extraction facet 12, 172 being arranged to reflect light guided in the second direction 193 towards an eye 45 of a viewer through the front guide surface 8, for example as illustrated in
In yet another alternative, the extraction waveguide 1 has a front guide surface 8 and a rear guide surface 6, and the rear guide surface 6 comprises a diffractive optical element 11B comprising the extraction features 169, for example illustrated in
Any of these alternative arrangements of extraction features 169 may be provided in the extraction waveguides 1 for the embodiments of
The alternative embodiment of
The transverse anamorphic component 60 comprises a light transmitting optical stack 610 comprising a partially reflective surface 214; a reflective linear polariser 218 and a polarisation conversion retarder 216.
The partially reflective surface 214 may comprise for example a partially transmissive metal layer that is formed on the surface 232A of a transmissive member 234A of a refractive lens 61. The reflective linear polariser 218 may be of the types as described elsewhere hereinabove.
In the embodiment of
At least one of the partially reflective surface 214 and the reflective linear polariser 218 has positive optical power in the transverse direction 197. In the illustrative embodiment of
The polarisation conversion retarder 216 is arranged to convert a polarisation state of light passing therethrough between a linear polarisation state and a circular polarisation state. For example linear polarisation state 964 is converted to circular polarisation state 962 or circular polarisation state 966 is converted to linear polarisation state 902.
The transverse anamorphic component 60 further comprises at least one lens element 61 comprising transmissive members 234A, 234B with respective outer surface 232A, 232B arranged on each side of the polarisation conversion retarder 216.
The at least one of the partially reflective surface 214 and the reflective linear polariser 218 that has positive optical power in the transverse direction 197 has no optical power in the lateral direction 195. Advantageously the partially reflective surface 214 and/or the reflective linear polariser 218 may be provided as a film that may be conveniently formed with a single plane of curvature without distortion of the film. For example the film may be conveniently adhered to a cylindrical surface with low cost and complexity and without degradation of the optical properties of the film.
The propagation of light rays 480T, 480C, 480B will now be described.
Considering the light rays 480T, 480C, 480B of
The extraction waveguide 1 has an input end 2 extending in the lateral and transverse directions 195, 197, the extraction waveguide 1 being arranged to receive light from the illumination system 240 through the input end 2, and the transverse anamorphic component 60 is disposed between the spatial light modulator 48 and the input end 2 of the extraction waveguide 1.
The transverse anamorphic component 60 comprises a further polarisation conversion retarder 212 that is disposed before a partially reflective surface 214 and a reflective linear polariser 218 in a direction 191 of transmission of light from the spatial light modulator 48, which is arranged to convert the linear polarisation state 960 to a circular polarisation state 962. Polarisation conversion retarder 212 may be optically bonded to the linear polariser 210, advantageously reducing reflections and stray light.
At incidence on the partially reflective surface 214, some of the light ray 480T. 480C, 480B is transmitted and refracted while some light is reflected as light ray 482 with polarisation state 961 because of the a phase shift at reflection at the partially reflective surface 214. The partially reflective surface 214 of
The circular polarisation state 962 is converted to linear polarisation state 964 by the polarisation conversion retarder 216. In the embodiment of
Light rays 480T, 480C, 480B are reflected at the reflective linear polariser 218 that is curved to provide optical power in the lateral direction 197 with wide spectral bandwidth. Linear polarisation state 964 is further converted to circular polarisation state 962 by a second pass through the polarisation conversion retarder 216; some of the light is reflected from partially reflective surface 214 with polarisation state 966; transmitted by a third pass through the polarisation conversion retarder 216 to provide polarisation state 902 that is transmitted by the reflective linear polariser 218. The curvature of the surface 232B of the lens 61 further provides refractive optical power at the output into air.
Clean-up polariser 70 may be provided to input polarisation state 902 into the input end 2 of the extraction waveguide 1.
In the embodiment of
The anamorphic near-eye display apparatus 100 may further comprise a linear polariser 70 arranged between the transverse anamorphic component 60 and the input end 2 of the extraction waveguide 1.
In the alternative embodiment of
In comparison to the embodiment of
Alternative arrangements of transverse anamorphic component 60 will now be described.
In the alternative embodiment of
By way of comparison, in the alternative embodiment of
It would be desirable to improve the aberrational performance of an anamorphic near-eye display apparatus 100, for example reducing the image blur for off-axis directions.
In operation, the lens 95 may be arranged to provide improved aberrations in the lateral direction 195 over a wider exit aperture eL. Thus the image blur 454 as illustrated in
In the alternative embodiment of
It may be desirable to reduce the size of the reflective end.
Fresnel reflector 84 is arranged to advantageously remove the sag of a domed reflective end 4 as illustrated in
In the alternative embodiment of
It would be desirable to increase the optical power of the lens 95 illustrated in
The alternative embodiment of
In the alternative embodiment of
The air gap 97 has edges 83, and the anamorphic near-eye display apparatus 100 further comprises reflectors that are air gap mirrors 96 extending across the edges 83 of the air gap 97. The air gap mirrors 96 provide trapping of guiding light in the region of the air gap 97. Advantageously efficiency is increased and spatial uniformity improved.
The waveguide in which the air gap 97 is formed is the extraction waveguide 1 and the light reversing reflector 140 is a reflective end 4 of the extraction waveguide 1. The lateral anamorphic component 110 further comprises the light reversing reflector 140. Advantageously size and complexity is reduced and efficiency increased.
By comparison with
It would be desirable to reduce the size of the lateral anamorphic component 110. Alternative arrangements of lateral anamorphic component 110 comprising Pancharatnam-Berry lenses will now be described.
In the alternative embodiment of an anamorphic near-eye display apparatus 100 of
In the alternative embodiment of
In operation, the Pancharatnam-Berry lens 350 provides optical power in the lateral direction 195(350) and no optical power in the transverse direction 197(350). The Pancharatnam-Berry lens 350 thus provides a similar operation to the curved reflective end 4 and curved reflective ends 4 with lens 95 described hereinabove. In alternative embodiments, not shown, the reflective end 4 may comprise a curved mirror and the optical power of the lateral anamorphic component 110 may be shared between the Pancharatnam-Berry lens 350 and the curved reflective end 4. Advantageously aberrations may be improved.
The alternative embodiments of
During manufacture, the alignment layer 352 may be formed for example by exposure and curing of a photoalignment layer with circularly polarised light with the desirable phase profile to achieve a variation of the optical axis direction 357. More specifically, an interference pattern is created between two oppositely circularly polarized wavefronts that creates locally linear polarized light whose orientation varies in the plane of the alignment layer to provide the desired alignment profile by the alignment layer 352. The alignment layer is thus oriented with linear polarized light to provide an optical axis direction 357 in the layer of liquid crystal material 354 that provides desirable optical power profile.
The layer of liquid crystal material 354 may have a thickness g that has a half wave thickness at a desirable wavelength of light, for example 550 nm. The liquid crystal material 354 may be a cured liquid crystal material such as a liquid crystal polymer or may be a nematic phase liquid crystal material arranged between opposing alignment layers.
At one location 161 of the Pancharatnam-Berry lens 350 that is typically the centre of the end 4 of the extraction waveguide 1, the liquid crystal molecules 354 are aligned such that there is no relative phase difference. Profile 358A illustrates the phase modulation for a first circular polarisation state (which may be right-handed circular polarisation state) and profile 358B illustrates the phase modulation for a second circular polarisation state orthogonal to the first polarisation state (which may be left-handed circular polarisation state).
The light rays 440, 442 incident onto the Pancharatnam-Berry lens 350 propagating along the direction 191 of the extraction waveguide 1 are polarised with the linear polarisation state 902.
For light ray 440 at the location 161, the incident polarisation state 902 is transmitted by the polarisation control retarder 72 with phase difference to provide circularly polarised state 922. The Pancharatnam-Berry lens 350 uses the polarisation control retarder 72 that is the same as the retarder used to optimise the transmission and reflectivity to polarised light of the dielectric layers of the extraction reflectors 170, 174, advantageously achieving improved efficiency.
The Pancharatnam-Berry lens 350 provides no relative phase modulation at the location 161, so that the reflection of light ray 440 from the light reversing reflector 140 provides the orthogonally circularly polarised state 924 that is transmitted as polarisation state 924 along the direction 193 back towards the extraction reflectors 169 that may be reflectors such as extraction reflectors 170, 174, 218 as described hereinabove.
For light ray 442 at the location offset by distance XL in the lateral direction 195 from the location 161, the incident polarisation state 902 is again transmitted by the polarisation control retarder 72 with phase difference to provide circularly polarised state 922. The Pancharatnam-Berry lens 350 provides a gradient of phase difference so that the ray 442 representing a planar phase front is deflected in comparison to an illustrative undeflected ray 444. After reflection from the light reversing reflector 140, a further phase shift is provided by the Pancharatnam-Berry lens 350 so that the light ray 442 undergoes a further deflection. The reflected ray 442 propagating in the direction 193 along the extraction waveguide 1 is parallel to the returning ray 440. Thus the Pancharatnam-Berry lens 350, light reversing reflector 140 and polarisation control retarder 72, achieve the desirable optical function of the lateral anamorphic component 110.
Advantageously the physical size of the lateral anamorphic component 110 is reduced and a more compact arrangement achieved. The phase profile may further provide correction for aberrations of the lateral anamorphic component 110.
In other embodiments, plural Pancharatnam-Berry lenses 350 or Pancharatnam-Berry lenses 350 in combination with refractive lenses 95, for example as illustrated in
It may be desirable to reduce image blur at higher lateral field angles.
The alternative embodiment of
The optical system 250 has an optical axis 199 and has anamorphic properties in a lateral direction 195 and a transverse direction 197 that are perpendicular to each other and perpendicular to the optical axis 199. The spatial light modulator 48 comprises pixels 222 distributed in the lateral direction 195.
The optical system 250 comprises: a transverse anamorphic component 60 having positive optical power in the transverse direction 197, wherein the transverse anamorphic component 60 is arranged to receive light from the spatial light modulator 48 and the illumination system 240 is arranged so that light output from the transverse anamorphic component 60 is directed in directions that are distributed in the transverse direction 197.
The extraction waveguide 1 is arranged to receive light rays 489 for respective pixels 222 and from the transverse anamorphic component 60.
The lateral anamorphic component 110 has positive optical power in the lateral direction 195 and the extraction waveguide 1 is arranged to guide light from the transverse anamorphic component 60 to the lateral anamorphic component 110 along the extraction waveguide 1 in a first direction 191.
The light reversing reflector 140 is arranged to reflect light that has been guided along the extraction waveguide 1 in the first direction 191 so that the reflected light is guided along the extraction waveguide 1 in a second direction 193 opposite to the first direction 191, wherein the extraction waveguide 1 comprises an array of extraction features 169 comprising extraction reflectors 174A-C, the extraction features 169 being arranged to transmit light guided along the extraction waveguide 1 in the first direction 191 and to extract light guided along the extraction waveguide 1 in the second direction 193 towards an eye 45 of a viewer, the array of extraction features 169 being distributed along the extraction waveguide 1 so as to provide exit pupil 40 expansion.
Returning to the description of
In practice, aberrations of the lateral anamorphic component 110 have Petzval field curvature with an illustrative curved field surface 98B shown in
It would be desirable to provide pixels 222 of the spatial light modulator 48 that are on a field surface 98A that is close to the pixel surface 224 of the illumination system 240 across the spatial light modulator 48 in the lateral direction 195.
Considering the embodiment of
In operation, light ray 480 is an illustrative light ray for output light from pixel 222 on the transverse anamorphic component 60 that is directed towards the eye 45 of an observer. Indicative light rays 450A. 451A, 450B, 451B illustrate light rays that would propagate from the eye 45 towards the spatial light modulator 48 if a light source were to be arranged at a location corresponding to the retina 46 of the eye 45. Indicative light rays 450A, 451A form indicative image point 223A and indicative light rays 450B, 451B form indicative image point 223B where indicative image points 223A, 223B lie in the surface 98A.
Considering the point of best focus 223B, the separation δAB of the surface 98A from the plane of the pixels 222 of the spatial light modulator 48 is reduced across the field of view in comparison to the separation 6B provided by surface 98B that would provide a point of best focus 223C.
In the alternative embodiment of
Alternative embodiments to reduce field curvature will now be described.
The alternative embodiments of
In comparison to non-anamorphic components, the curvature may be arranged about only one axis. In particular, the spatial light modulator 48 may comprise a silicon or glass backplane. Such backplanes are not typically suitable for curvature about two axes. However in the present embodiments, single axis curvature may achieve desirable correction for field curvature. Advantageously the cost of achieving a suitably curved spatial light modulator 48 may be reduced.
Returning to the description of
Ray 404RGB is reflected by the extraction reflector 170 to the front guide surface 8 at location 229 provide the output light rays 404R, 404G, 404B separated by an angle of colour blur 455.
It would be desirable to reduce colour blur 455.
In comparison to
In the alternative embodiment of
Arrangements of colour sub-pixels 222R, 222G, 222B to provide the pixel array of
The alternative embodiments of
Considering the alternative embodiment of
In the alternative embodiment of
In the alternative embodiment of
Considering the alternative embodiment of
It may be desirable to reduce the complexity of the spatial light modulator 48 while achieving reduced chromatic blur 455 and image distortion.
With reference to the exemplary method illustrated in
In a second step S2, the colour channel is selected, for example the red colour channel.
In a third step S3, the corrected colour sub-pixel location 222R on the spatial light modulator 48 is calculated. Steps S2 and S3 area repeated for the three colour sub-pixels 222G, 222B.
In a fourth step S4, image data is addressed to the respective pixel location such that the correct image data is sent to the correct direction. The steps S1-S4 are then repeated for each image angular location, for example as illustrated by the array of
With reference to the exemplary method illustrated in
An alternative embodiment comprising the method of
In alternative embodiments, the method of
It may be desirable to provide further reduction of chromatic image blur 455 that arises from refraction at the front light guide surface 8.
In the present description, the colour pixels 222R, 222G, 222B may more generally be provided by other or alternative wavelength bands including but not limited to white sub-pixels, yellow sub-pixels, magenta sub-pixels and cyan sub-pixels. The pixel 222 may comprise three sub-pixels or a number of sub-pixels different to three, for example one sub-pixel in a monochromatic display apparatus 100 or four sub-pixels in an extended colour gamut display apparatus 100.
In the alternative embodiment of
The colour splitting diffractive optical element 142 may be a grating, such as a Pancharatnam-Berry lens, with operation as described elsewhere herein with respect to
Alternative arrangements of illumination systems and transverse anamorphic components 60 will now be described.
In the alternative embodiment of
Advantageously aberrations in the transverse direction 197(60) may be improved.
Further, the illumination system may comprise a reflective spatial light modulator 48, an illumination array 302 comprising light sources 304 and a beam combiner cube arranged to illuminate the spatial light modulator 48. The illumination array 302 may comprise different coloured light sources so that the spatial light modulator 48 may provide time sequential colour illumination.
The alternative embodiment of
In the alternative embodiment of
Additionally or alternatively curved mirror 86B may be provided to increase efficiency of operation.
Spatial light modulator 48 comprises active area 49A and border 49B and is aligned to the lens of the transverse anamorphic component 60 that is a compound lens comprising lenses 60A-F. Some of the lenses 60A-F may comprise surfaces that have a constant radius and some may comprise variable radius surfaces such that in combination aberration correction is advantageously improved. Some of the lenses 60A-F may comprise aspheric surfaces to achieve improved aberrations, such as reducing field curvature.
Alternative arrangements of spatial light modulator 48, illumination system 240 and optical system 250 will now be described.
In the alternative embodiment of
The beam 490 is arranged to illuminate a screen 52 to provide a diffuse light source 55 at the screen. The screen 52 may comprise a diffusing arrangement so that the transmitted light is diffused into light cone 491 arranged to provide input light rays 492 into the transverse anamorphic component 60 and extraction waveguide 1.
The screen 52 may alternatively comprise a photoemission layer such as a phosphor laser at which the laser beam 490 is arranged to produce emission from the photoemission layer. The output colour can advantageously be independent of the laser 50 emission wavelength. Further laser speckle may be reduced.
The laser 50 may comprise a one dimensional array of laser emitting pixels 222 across a row 221T and the scanning arrangement 51 may provide one dimensional array of light sources 55 at the screen 52 for each addressable row of the spatial light modulator 48. The scanning speed of the scanning arrangement 51 is reduced, advantageously achieving reduced cost and complexity.
Alternatively the laser 50 may comprise a single laser emitter and the scanning arrangement 51 may provide two dimensional scanning of the beam 490 to achieve a two dimensional pixel array of emitters 55 at the screen 52. Advantageously laser 50 cost may be reduced.
Further arrangements comprising laser sources will now be described.
The alternative embodiment of
Returning to the description of
In other words, the scanning arrangement 51 scans about the lateral direction 197(60) and serves to provide illustrative light rays 490A, 490B sequentially. By means of sequential scanning, the scanning arrangement 51 effectively has positive optical power in the transverse direction 197(60) for light from the spatial light modulator 48, achieving output cone 491 in a sequential manner. In this manner, the scanning arrangement 51 directs light in directions that are distributed in the transverse direction, allowing it to serve as a transverse anamorphic component 60. The scanning of the scanning arrangement 51 may be arranged not to direct light near to parallel to the direction 191 along the extraction waveguide 1. Advantageously double imaging is reduced.
Advantageously the cost and complexity of the illumination system 240 and transverse anamorphic component 60 may be reduced.
The alternative embodiment of
Embodiments including alternative forms of reflective extraction features 169 to those of
In the alternative embodiment of
By way of comparison with
The anamorphic near-eye display apparatus 100 of
It may be desirable to improve the image luminance uniformity.
In comparison to
In the alternative embodiment of
The anamorphic near-eye display apparatus 100 of
It may be desirable to increase the efficiency of operation and to reduce the complexity of manufacture.
The anamorphic near-eye display apparatus 100 comprises: an illumination system 240 comprising a spatial light modulator 48, the illumination system 240 being arranged to output light; and an optical system 250 arranged to direct light from the illumination system 240 to the pupil 44 of a viewer's eye 45, wherein the optical system 250 has an optical axis 199 and has anamorphic properties in a lateral direction 195 and a transverse direction 197 that are perpendicular to each other and perpendicular to the optical axis 199, wherein the spatial light modulator 48 comprises pixels 222 distributed in the lateral direction 195, and the optical system 250 comprises: a transverse anamorphic component 60 having positive optical power in the transverse direction 197, wherein the transverse anamorphic component 197 is arranged to receive light from the spatial light modulator 48 and the illumination system 240 is arranged so that light output from the transverse anamorphic component 60 is directed in directions that are distributed in the transverse direction 197, an extraction waveguide 1 arranged to receive light from the transverse anamorphic component 60; a lateral anamorphic component 110 having positive optical power in the lateral direction 195, the extraction waveguide 1 being arranged to guide light from the transverse anamorphic component 60 to the lateral anamorphic component 195 along the extraction waveguide 1 in a first direction 191; and a light reversing reflector 140 that is arranged to reflect light guided along the extraction waveguide 1 in the first direction 191 to form light that is guided along the extraction waveguide 1 in a second direction 193 opposite to the first direction.
The extraction waveguide 1 comprises: a front guide surface 8; a polarisation-sensitive reflector 702 opposing the front guide surface 8; and an extraction element 169 disposed outside the polarisation-sensitive reflector 702, the extraction element 169 comprising: a rear guide surface 6 opposing the front guide surface 8; and an array of extraction features 272A-D.
The anamorphic near-eye display apparatus 100 is arranged to provide light 401 guided along the extraction waveguide 1 in the first direction 191 with an input linear polarisation state 902 before reaching the polarisation-sensitive reflector 702; and the optical system 250 further comprises a polarisation conversion retarder 72 disposed between the polarisation-sensitive reflector 702 and the light reversing reflector 140, wherein the polarisation conversion retarder 72 is arranged to convert a polarisation state of light passing therethrough between a linear polarisation state 902 and a circular polarisation state 922, and the polarisation conversion retarder 72 and the light reversing reflector 140 are arranged in combination to rotate the input linear polarisation state 902 of the light guided in the first direction 191 so that the light guided in the second direction 193 and output from the polarisation conversion retarder 72 has an orthogonal linear polarisation state 904 that is orthogonal to the input linear polarisation state 902; the polarisation-sensitive reflector 702 is arranged to reflect light guided in the first direction having the input linear polarisation state 902 and to pass light guided in the second direction 193 having the orthogonal linear polarisation state 194, so that the front guide surface 8 and the polarisation-sensitive reflector 702 are arranged to guide light 401 in the first direction 191, and the front guide surface 8 and the rear guide surface 6 are arranged to guide light 406 in the second direction 193, and the array of extraction features 172 is arranged to extract light guided along the extraction waveguide 1 in the second direction 193 towards an eye 45 of a viewer through the front guide surface 8, the array of extraction features 172 being distributed along the extraction waveguide 1 so as to provide exit pupil expansion 40 in the transverse direction 197.
Extraction waveguide 1 comprises waveguide member IIlA between the front guide surface 8 and polarisation-sensitive reflector 700 and waveguide member 111B between the polarisation-sensitive reflector 700 and the rear guide surface 6.
Considering
The polarisation-sensitive reflector 700 may comprise a reflective linear polariser 702, or a dielectric stack for example. Light ray 401 has a polarisation state 902 provided by the input polariser 70 and propagates in the direction 191 by guiding between the polarisation-sensitive reflector 700 and the front guide surface 8.
The light cone 491T is incident on the reflective linear polariser 702 and is reflected such that a replicated light cone 491Tf is provided propagating along the extraction waveguide 1 in the direction 191.
The reflected light cones 493T, 493Tf propagate along the second direction 193 about optical axes 199(60) and 199f(60). Corresponding transverse directions 197(60), 197f(60) are also indicated.
Reflected light rays propagating in the second direction 193 along the extraction waveguide 1 have polarisation state 904 that is provided by polarisation conversion retarder 72 (that may be a quarter waveplate for example) at or near the lateral anamorphic component 110 and reflection from the light reversing reflector 140.
Both cones 493T, 493Tf comprise image data that between the cones 493T, 493Tf is flipped about the direction 191 and thus provides degeneracy of ray directions for a given pixel 222 on the spatial light modulator 48. It is desirable to remove such degeneracy so that only one of the cones 493T, 493Tf is extracted and a secondary image is not directed to the pupil 44 of the eye 45.
Output light ray 401 propagates by total internal reflection of opposing surfaces 6, 8 until it is incident on a guide surface 176 at which at least some light is reflected, and then at extraction facet 172 at which at least some light is further reflected as will be described further hereinbelow such that light cone 493T is preferentially directed towards the front guide surface 8. After refraction at the light guide surface 8, light in the cone 495T is extracted towards the eye 45, with a cone angle that has increased size compared to the cone 493T.
The extraction facets 172A-E are inclined at the same angle, such that for each of the light extraction facets 172A-E of
By way of comparison, the light cone 493Tf around light ray 461 which is incident on the surface 8 and then directly incident on extraction facet 172 without first reflecting from the guide surface 176 for preferential transmission through the extraction facet 172, and light cone 493Tf is not directed towards the eye 45. Degeneracy is reduced or removed and image cross-talk or reflected images are advantageously reduced.
The present embodiments enable the uniformity of output to be improved in comparison to the anamorphic near-eye display apparatus 100 of
In the alternative embodiment of
The anamorphic near-eye display apparatus 100 is arranged to provide light guided along the extraction waveguide 1 in the first direction 191 with an input linear polarisation state 902 before reaching the polarisation-sensitive reflector 702.
A polarisation conversion retarder 89 is disposed between the reflective linear polariser 99 and the light reversing reflector 140 is a first polarisation conversion retarder 89. The anamorphic near-eye display apparatus 100 comprises a second polarisation conversion retarder 87 arranged between the polarisation-sensitive reflector 702 and the reflective linear polariser 99, the second polarisation conversion retarder 87 being arranged to convert from a state that is parallel or orthogonal to the input linear polarisation state 902 to a polarisation state 990 that has a component parallel to the input linear polarisation state 902 and a component orthogonal to the input linear polarisation state 902.
The anamorphic near-eye display apparatus 100 comprises an absorptive linear polariser 85 arranged to pass the component 991 orthogonal to the input linear polarisation state 902. In an alternative embodiment, the absorptive linear polariser 85 may be arranged to pass the component parallel to the input linear polarisation state 902.
The reflective linear polariser 99 is arranged to pass the same component 991 as the absorptive linear polariser 85.
The second polarisation conversion retarder 87, the absorptive linear polariser 85, the reflective linear polariser 99, the first polarisation conversion retarder 89 and the light reversing reflector 140 are arranged in combination to rotate the input linear polarisation state 902 of the light guided in the first direction 191 so that the light guided in the second direction 193 and output from the second polarisation conversion retarder 87 has a linear polarisation state 997 that has a component 999P parallel to the input linear polarisation state 902 and a component 999S orthogonal to the input linear polarisation state 902.
The polarisation-sensitive reflector 702 is arranged to reflect light guided in the first direction 191 having the input linear polarisation state 902 and to pass the component 999S of light guided in the second direction 193 that is orthogonal to the input linear polarisation state 902, so that the front guide surface 8 and the polarisation-sensitive reflector 702 are arranged to guide light in the first direction 191, and the front guide surface 8 and the rear guide surface 6 are arranged to guide the component 999S of light that is orthogonal to the input linear polarisation state 902 in the second direction 193.
The polarisation-sensitive reflector 702 may comprise a reflective linear polariser or at least one dielectric layer.
The alternative embodiment of
Advantageously improved aberrations may be achieved in at least the lateral direction 195 and an extraction waveguide 1 with reduced cost and complexity may be provided.
An alternative extraction arrangement will now be described.
By way of comparison with
In the embodiment of
Considering
The polarisation-sensitive reflector 700 may comprise reflective polarisers 702, dichroic stacks 712 or other types of polarisation-sensitive reflectors. The partially reflective layer 275 may be provided by dichroic stacks 276, metallic layers or other partially reflective layers. The partially reflective layers 275 may be polarisation sensitive.
By way of comparison with the embodiments of
The anamorphic near-eye display apparatus 100 of
It may be desirable to further reduce the cost and complexity of the extraction waveguide 1.
Considering the alternative embodiment of
The diffractive optical element 11B is arranged to provide extraction of some of the light guided in the extraction waveguide 1 between the opposing rear and front guide surfaces 6, 8, wherein the diffractive optical element 11B is arranged between the opposing rear and front guide surfaces 6, 8. Central ray 460C on the optical axis 199(60) along the first direction 191 of the extraction waveguide 1 is partially reflected by the diffractive optical element 11B to output light 464 away from the eye 45. After reflection at the light reversing reflector, light is further reflected.
Advantageously the extraction features 169 that are diffractive optical element 11B may be conveniently manufactured and attached to the transmissive element 11A.
The anamorphic near-eye display apparatus 100 of
The features of
Head-wear 600 comprising the anamorphic near-eye display apparatus 100 will now be described.
The head-worn display apparatus 600 may comprise a pair of spectacles 600 comprising the anamorphic near-eye display apparatus 100 described elsewhere herein that is arranged to extend across at least one eye 45 of a viewer 47 when the head-worn display apparatus 600 is worn. The head-worn display apparatus 600 may comprise a pair of spectacles comprising spectacle frames 602 with rims 603 and arms 604, which serve as a head-mounting arrangement arranged to mount the anamorphic near-eye display apparatus 100 on a head of a wearer with the anamorphic near-eye display apparatus 100 extending across at least one eye of the wearer. In general, any other head-mounting arrangement may alternatively be provided. The rims 603 and/or arms 604 may comprise electrical systems for at least power, sensing and control of the illumination system 240. The anamorphic near-eye display apparatus 100 of the present embodiments may be provided with low weight and may be transparent. The head-worn display apparatus 600 may be tethered by wires to remote control system or may be untethered for wireless control. Advantageously comfortable viewing of augmented reality content may be provided.
It may be desirable to provide improved aesthetic appearance of the anamorphic near-eye display apparatus 100.
The eyepiece arrangement 102 may be arranged within the head-worn display apparatus 600 and may comprise the anamorphic near-eye display apparatus 100. The extraction waveguide 1 may be embedded with a substrate 103 that extends around the components 170, 110 of the anamorphic near-eye display apparatus 100. The shape of the substrate 103 may be profiled to fit various shaped head-worn display apparatus, for example spectacles. Advantageously aesthetic appearance may be improved.
The edge 105 of the substrate 103 may be provided with a light absorbing surface that absorbs incident light from the anamorphic near-eye display apparatus 100. The light absorbing surface may be a structured anti-reflection surface that is coated with an absorbing material. Advantageously image contrast is improved.
It may be desirable to change the illumination system 240 positioning in the head-worn display apparatus 600.
The eye-piece arrangement 102 comprising substrate 103 may further be provided for others of the embodiments of the present disclosure.
In comparison to the arrangement of
It would be desirable to provide a virtual reality head-worn display apparatus 600 in which the head-worn display apparatus is not transparent to external images.
The alternative embodiment of head-worn display apparatus 600 of
Alternative arrangements of anamorphic near-eye display apparatus comprising an input waveguide and separate extraction waveguide will now be described.
Input waveguide 1A is arranged to guide light rays 400 in cone 491A from the transverse anamorphic component 60 to partially reflective mirror 7 along the input waveguide 1A in direction 191A. The input waveguide 1A has opposing rear and front guide surfaces 6A, 8A that are planar and parallel. The input waveguide 1A further has an input face 2A extending in the lateral and transverse directions 195(60), 197(60), the input waveguide 1A being arranged to receive light 400 from the illumination system 240 through an input face 2A. The input face 2A extends in the lateral direction 195 between edges 22A, 24A of the input waveguide 1A, and extends in the transverse direction 197 between opposing rear and front guide surfaces 6A, 8A of the input waveguide 1A. The output face 4A of the input waveguide 1B is arranged to output light towards the partially reflective mirror 7.
The input waveguide 1A and the intermediate waveguide 1C comprise no extraction features that are arranged to extract light guided therealong. In operation input waveguide 1A is arranged to guide light rays 400 between the opposing rear and front guide surfaces 6, 8 as illustrated by the zig-zag paths of guided rays 401 in both input waveguide 1A. Advantageously light may be directed with high efficiency from the transverse anamorphic component 60 to the partially reflective mirror 7 and images may be provided with reduced image blur.
Partially reflective mirror 7 is arranged to receive light from the input waveguide 1A. Partially reflective mirror 7 may be arranged within a mirror waveguide 1D with edges 22D, 24D, input face 2D, waveguide output face 4DC and waveguide output face 4DB.
Air gaps 3AD, 3DC and 3DB are arranged between mirror waveguide 1D and input waveguide 1A, intermediate waveguide 1C and extraction waveguide 1B respectively. Some light rays may guide within the mirror waveguide 1D. The operation of the air gaps 3 will be described further hereinbelow with respect to
In general, the mirror 7 of the mirror waveguide 1D is arranged to direct at least some of the light from the input waveguide 1A into the intermediate waveguide 1C.
Partially reflective mirror 7 may comprise partially reflective layers such as air gaps, reflective polarisers or dielectric layers. Partially reflective mirror 7 may provide a polarisation-sensitive reflectivity and polariser 70 may be provided as described hereinbelow in
Partially reflective mirror 7 may be further arranged to transmit light that is reflected by light reversing reflector 140 of the intermediate waveguide 1C. In alternative embodiments the partially reflective mirror 7 may be arranged to transmit light from the input waveguide 1A and reflect light from the intermediate waveguide 1C.
Intermediate waveguide 1C is arranged to receive at least some of the light from the partially reflective mirror 7 and comprises a light reversing reflector 140 that is arranged to reflect light in light cones 491C that has been guided in the first direction 191C along the intermediate waveguide 1C in the first direction 191C so that the reflected light in light cone 493C is guided along the intermediate waveguide 1C in a second direction 193C opposite to the first direction 191C, and towards the partially reflective mirror 7 and extraction waveguide 1B.
The intermediate waveguide 1C further has an input face 2C extending in the lateral and transverse directions 195(60), 197(60), the intermediate waveguide 1C being arranged to receive light 400 from the partially reflective mirror 7. The input face 2C extends in the lateral direction 195 between edges 22C, 24A of the intermediate waveguide 1C, and extends in the transverse direction 197C between opposing rear and front guide surfaces 6C, 8C of the intermediate waveguide 1C.
The intermediate waveguide 1C may comprise no extraction features that are arranged to extract light guided therealong. The front and rear guide surfaces 8C, 6C of the intermediate waveguide 1C are planar and parallel. Advantageously light may be transmitted along the intermediate waveguide 1C with high efficiency and image blur of the output image is reduced.
In the embodiment of
The optical system 250 is thus arranged so that light output from the lateral anamorphic component 110 is directed in directions that are distributed in the transverse direction 197(110) and the lateral direction 195(110). The curved shape of the reflective end 4C may be a shape that is the cross section of a sphere, ellipse, parabola or other aspheric shape to achieve desirable imaging of light rays from the spatial light modulator 48 to the pupil 44 of the eye 45 as will be described further hereinbelow.
The reflected light from the light reversing reflector 140 is output from the intermediate waveguide 1C and incident on the mirror waveguide 1D with a polarisation state 902 that is preferentially transmitted by the partially reflective mirror 7. Advantageously efficiency may be increased.
Extraction waveguide 1B is arranged to receive light from the lateral anamorphic component, 110.
The extraction waveguide 1B further has an input face 2B extending in the lateral and transverse directions 195(60), 197(60), the extraction waveguide 1B being arranged to receive light 400 from the partially reflective mirror 7. The input face 2B extends in the lateral direction 195 between edges 22B, 24B of the extraction waveguide 1B, and extends in the transverse direction 197B between opposing rear and front guide surfaces 6B, 8B of the extraction waveguide 1B. The output face 4B of the extraction waveguide 1B may for example comprise a light absorbing material. Advantageously stray light may be reduced.
The extraction waveguide 1B has a front guide surface and a rear guide surface 8B, 6B, and the rear guide surface 6B comprises extraction facets 270 that are the reflective extraction features 169. The extraction waveguide comprises an array of reflective extraction features 170a-n, the reflective extraction features 170a-n being arranged to extract light guided along the extraction waveguide 1B towards an eye 45 of a viewer, the array of reflective extraction features 170a-n being distributed along the extraction waveguide 1B so as to provide exit pupil expansion.
The extraction waveguide 1B comprises extraction facets 270 and intermediate surfaces 272 extending along the extraction waveguide between adjacent pairs of extraction reflectors 270 and that are arranged on the rear light guide surface 6B. In the embodiment of
In the embodiment of
By way of comparison with
The extraction reflectors 170 extend partially across the extraction waveguide 1B between opposing rear and front guide surfaces 6, 8 of the extraction waveguide 1B with successively shifted positions. The successively shifted positions are arranged along the waveguide in the direction 191B. In other words, in the transverse direction 197 the extraction reflectors 170 extend partially across the extraction waveguide 1B with successively shifted positions.
The input linear polariser 70 is disposed between the spatial light modulator 48 and the partially reflective mirror 7 which in the embodiment of
In the alternative embodiment of
After reflection at the light reversing reflector 140, orthogonal circular polarisation state 922 is provided and the polarisation conversion retarder 72C provides p-polarisation linear state 902 back towards the partially reflective mirror 7 that is preferentially transmitted towards the extraction waveguide 1B. Increased transmission of the partially reflective mirror 7 may be achieved for light rays propagating towards the extraction waveguide 1B.
The optical system 250 further comprises a further polarisation conversion retarder 72B disposed between the the partially reflective mirror 7 and the extraction waveguide 1B, the polarisation conversion retarder 72B being arranged to convert a polarisation state of light passing therethrough between a linear polarisation state 902 and an orthogonal linear polarisation state 904, wherein the further polarisation conversion retarder 72B has a retardance of a half wavelength at a wavelength of visible light. As will be described hereinbelow, the further polarisation conversion retarder 72B provides polarisation state 904 incident onto the extraction reflectors 170. Advantageously improved efficiency may be achieved as will be described hereinbelow.
The alternative embodiment of
The further polarisation conversion retarder 72C of
By way of comparison with
In comparison to the embodiment of
Such an arrangement may achieve the desirable aberration and size improvements of
The illumination system 240 and optical system 250 of the embodiments hereinabove may be provided for anamorphic directional illumination devices for illumination of external scenes 479.
The alternative embodiment of
Optical system 250 is arranged to direct light from the illumination system 240. The light in light cone 499 may be directed towards an externally illuminated scene 479. Illuminated scenes 479 may include but are not limited to roads, rooms, external spaces, processing equipment, metrology environments, theatrical stages, human bodies such as for face illumination for face detection and measurement purposes.
The optical system 250 has an optical axis 199 and has anamorphic properties in a lateral direction 195 and a transverse direction 197 that are perpendicular to each other and perpendicular to the optical axis 199, wherein the light source array 948 comprises light sources 949a-n distributed in the lateral direction 195, and which may further be distributed in the transverse direction 197 as described elsewhere herein.
The optical system 250 further comprises a transverse anamorphic component 60 having positive optical power in the transverse direction 197, wherein the transverse anamorphic component 60 is arranged to receive light from the light source array 948 and the illumination system 250 is arranged so that light output from the transverse ananorphic component 60 is directed in directions that are distributed in the transverse direction 197.
The optical system 250 further comprises an extraction waveguide 1 arranged to receive light from the transverse anamorphic component 60 and a lateral anamorphic component 110 having positive optical power in the lateral direction 195, the extraction waveguide 1 being arranged to guide light in light cone 491 from the transverse anamorphic component 60 to the lateral anamorphic component 110 along the extraction waveguide 1 in a first direction 191.
A light reversing reflector 140 is arranged to reflect light that has been guided along the extraction waveguide 1 in the first direction 191 so that the reflected light in light cone 493 is guided along the extraction waveguide 1 in a second direction 193 opposite to the first direction 191.
The extraction waveguide 1 comprises at least one reflective extraction feature 970 disposed internally within the extraction waveguide 1, the at least one reflective extraction feature 970 being arranged to transmit light guided along the extraction waveguide 1 in the first direction 191 and to extract light guided along the extraction waveguide 1 in the second direction 193 to provide output light cone 499 directed towards the illuminated scene 479.
The anamorphic directional illumination device 1000 of
As illustrated in
As illustrated in
As illustrated in
As illustrated in
As illustrated in
As illustrated in
By way of comparison with the anamorphic near-eye display apparatuses 100 described hereinabove, the output light from the anamorphic directional illumination device 1000 is provided as illumination cones 951a-n for illumination of a scene 479 compared to the angular pixel information for illumination of pupil 44 and retina 46. High resolution imaging of illuminated scenes 479 may be achieved with high efficiency and low cost in a compact package.
The light sources 949 may output light that is visible light or infra-red light. Advantageously directional illumination of scenes 479 may be provided for visible illumination or illumination of scenes for other detectors such as LIDAR detectors. The light sources 949 may have different spectral outputs. The different spectral outputs include: a white light spectrum, plural different white light spectra, red light, orange light, and/or infra-red light. A visible illumination may be provided and a further illumination for detection purposes may also be provided, which may have different illumination structures to achieve improved signal to noise of detection.
In an alternative embodiment, the scene 479 may comprise a projection screen and the anamorphic directional illumination device 1000 may provide projection of images onto the projection screen. Advantageously a lightweight and portable image projector with high efficiency may be provided in a thin package.
The reflective extraction feature 970 of
Alternative embodiments of waveguide 1 arrangements, transverse anamorphic component 60 arrangements, lateral anamorphic component 110 arrangements and extraction feature 970 arrangements may be provided as described elsewhere hereinabove.
The alternative embodiment of
The vehicle external light apparatus 106 provides output light cone 499 so that the horizon 499 and road surface 494 may be illuminated. In the example of
The light source array 948 may be controlled by controller 500 in response to the location of objects such as other drivers or road hazards in the illuminated scene 479. The light cone 499 may be arranged to illuminate a two dimensional array of light cones 951 corresponding to respective light sources 949. The light sources 949a-n may be individually or collectively controllable so that some parts of the scene 479 are illuminated and other parts are not illuminated or illuminated with different illuminance. Advantageously glare to other drivers may be reduced while providing increased levels of illuminance of the road scene 479.
While various embodiments in accordance with the principles disclosed herein have been described above, it should be understood that they have been presented by way of example only, and not limitation. Thus, the breadth and scope of this disclosure should not be limited by any of the above-described exemplary embodiments, but should be defined only in accordance with any claims and their equivalents issuing from this disclosure. Furthermore, the above advantages and features are provided in described embodiments, but shall not limit the application of such issued claims to processes and structures accomplishing any or all of the above advantages.
Additionally, the section headings herein are provided for consistency with the suggestions under 37 CFR 1.77 or otherwise to provide organizational cues. These headings shall not limit or characterize the embodiment(s) set out in any claims that may issue from this disclosure. Specifically and by way of example, although the headings refer to a “Technical Field,” the claims should not be limited by the language chosen under this heading to describe the so-called field. Further, a description of a technology in the “Background” is not to be construed as an admission that certain technology is prior art to any embodiment(s) in this disclosure. Neither is the “Summary” to be considered as a characterization of the embodiment(s) set forth in issued claims. Furthermore, any reference in this disclosure to “invention” in the singular should not be used to argue that there is only a single point of novelty in this disclosure. Multiple embodiments may be set forth according to the limitations of the multiple claims issuing from this disclosure, and such claims accordingly define the embodiment(s), and their equivalents, that are protected thereby. In all instances, the scope of such claims shall be considered on their own merits in light of this disclosure, but should not be constrained by the headings set forth herein.
| Number | Date | Country | |
|---|---|---|---|
| 63354676 | Jun 2022 | US | |
| 63358413 | Jul 2022 | US | |
| 63392683 | Jul 2022 | US | |
| 63397251 | Aug 2022 | US | |
| 63423998 | Nov 2022 | US | |
| 63447977 | Feb 2023 | US | |
| 63402571 | Aug 2022 | US | |
| 63424012 | Nov 2022 | US |
