Patent Application
20230161093
The present disclosure relates generally to optical devices and, more specifically, to a light guide display system for providing an increased power efficiency.
An artificial reality system, such as a head-mounted display (“HMD”) or heads-up display (“HUD”) system, generally includes a near-eye display (“NED”) system in the form of a headset or a pair of glasses, and configured to present content to a user via an electronic or optic display within, for example, about 10-20 mm in front of the eyes of a user. The NED system may display virtual objects or combine images of real objects with virtual objects, as in virtual reality (“VR”), augmented reality (“AR”), or mixed reality (“MR”) applications. For example, in an AR system, a user may view both images of virtual objects (e.g., computer-generated images (“CGIs”)) and the surrounding environment by, for example, seeing through transparent display glasses or lenses (also referred to as an optical see-through AR system).
One example of an optical see-through AR system may include a pupil-expansion light guide display system, in which an image light representing a CGI may be coupled into a light guide (e.g., a transparent substrate), propagate within the light guide, and be coupled out of the light guide at different locations to expand an effective pupil. Diffractive optical elements may be coupled with the light guide to couple the image light into or out of the light guide via diffraction, such as surface relief gratings, holographic gratings, metasurface gratings, etc.
Consistent with an aspect of the present disclosure, a device is provided. The device includes a light guide. The device also includes an in-coupling element coupled with the light guide and configured to couple a first image light into the light guide as a second image light propagating inside the light guide via total internal reflection (“TIR”), and to couple a portion of the second image light out of the light guide as a third image light. The device further includes a recycling element coupled with the light guide and configured to couple the third image light back into the light guide as a fourth image light propagating inside the light guide via TIR.
Consistent with another aspect of the present disclosure, a device is provided. The device includes a light guide. The device also includes an in-coupling grating coupled with the light guide and configured to couple, via diffraction, a first image light having a first polarization into the light guide as a second image light propagating inside the light guide via total internal reflection (“TIR”). The device also includes a retardation film coupled with the light guide and configured to convert the second image light incident thereon as a third image light having a second polarization that is orthogonal to the first polarization. The in-coupling grating is configured to receive the third image light having the second polarization from the retardation film and allow the third image light to propagate inside the light guide via TIR as a fourth image light.
Consistent with another aspect of the present disclosure, a device is provided. The device includes a light guide. The device also includes an in-coupling element coupled with the light guide and configured to couple a first image light into the light guide as a second image light. The device also includes an out-coupling element coupled with the light guide and including a plurality of out-coupling gratings configured to be selectively activated to couple the second image light out of the light guide. The device also includes at least one redirecting element coupled with the light guide. The device further includes a controller configured to control the in-coupling element to selectively direct the second image light to propagate in one of a plurality of selectable directions inside the light guide. The at least one redirecting element is configured to redirect the second image light when the second image light is received from the in-coupling element, to propagate toward a predetermined portion of the out-coupling element.
Other aspects of the present disclosure can be understood by those skilled in the art in light of the description, the claims, and the drawings of the present disclosure. The foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the claims.
The following drawings are provided for illustrative purposes according to various disclosed embodiments and are not intended to limit the scope of the present disclosure. In the drawings:
Embodiments consistent with the present disclosure will be described with reference to the accompanying drawings, which are merely examples for illustrative purposes and are not intended to limit the scope of the present disclosure. Wherever possible, the same reference numbers are used throughout the drawings to refer to the same or similar parts, and a detailed description thereof may be omitted.
Further, in the present disclosure, the disclosed embodiments and the features of the disclosed embodiments may be combined. The described embodiments are some but not all of the embodiments of the present disclosure. Based on the disclosed embodiments, persons of ordinary skill in the art may derive other embodiments consistent with the present disclosure. For example, modifications, adaptations, substitutions, additions, or other variations may be made based on the disclosed embodiments. Such variations of the disclosed embodiments are still within the scope of the present disclosure. Accordingly, the present disclosure is not limited to the disclosed embodiments. Instead, the scope of the present disclosure is defined by the appended claims.
As used herein, the terms “couple,” “coupled,” “coupling,” or the like may encompass an optical coupling, a mechanical coupling, an electrical coupling, an electromagnetic coupling, or any combination thereof. An “optical coupling” between two optical elements refers to a configuration in which the two optical elements are arranged in an optical series, and a light output from one optical element may be directly or indirectly received by the other optical element. An optical series refers to optical positioning of a plurality of optical elements in a light path, such that a light output from one optical element may be transmitted, reflected, diffracted, converted, modified, or otherwise processed or manipulated by one or more of other optical elements. In some embodiments, the sequence in which the plurality of optical elements are arranged may or may not affect an overall output of the plurality of optical elements. A coupling may be a direct coupling or an indirect coupling (e.g., coupling through an intermediate element).
The phrase “at least one of A or B” may encompass all combinations of A and B, such as A only, B only, or A and B. Likewise, the phrase “at least one of A, B, or C” may encompass all combinations of A, B, and C, such as A only, B only, C only, A and B, A and C, B and C, or A and B and C. The phrase “A and/or B” may be interpreted in a manner similar to that of the phrase “at least one of A or B.” For example, the phrase “A and/or B” may encompass all combinations of A and B, such as A only, B only, or A and B. Likewise, the phrase “A, B, and/or C” has a meaning similar to that of the phrase “at least one of A, B, or C.” For example, the phrase “A, B, and/or C” may encompass all combinations of A, B, and C, such as A only, B only, C only, A and B, A and C, B and C, or A and B and C.
When a first element is described as “attached,” “provided,” “formed,” “affixed,” “mounted,” “secured,” “connected,” “bonded,” “recorded,” or “disposed,” to, on, at, or at least partially in a second element, the first element may be “attached,” “provided,” “formed,” “affixed,” “mounted,” “secured,” “connected,” “bonded,” “recorded,” or “disposed,” to, on, at, or at least partially in the second element using any suitable mechanical or non-mechanical manner, such as depositing, coating, etching, bonding, gluing, screwing, press-fitting, snap-fitting, clamping, etc. In addition, the first element may be in direct contact with the second element, or there may be an intermediate element between the first element and the second element. The first element may be disposed at any suitable side of the second element, such as left, right, front, back, top, or bottom.
When the first element is shown or described as being disposed or arranged “on” the second element, term “on” is merely used to indicate an example relative orientation between the first element and the second element. The description may be based on a reference coordinate system shown in a figure, or may be based on a current view or example configuration shown in a figure. For example, when a view shown in a figure is described, the first element may be described as being disposed “on” the second element. It is understood that the term “on” may not necessarily imply that the first element is over the second element in the vertical, gravitational direction. For example, when the assembly of the first element and the second element is turned 180 degrees, the first element may be “under” the second element (or the second element may be “on” the first element). Thus, it is understood that when a figure shows that the first element is “on” the second element, the configuration is merely an illustrative example. The first element may be disposed or arranged at any suitable orientation relative to the second element (e.g., over or above the second element, below or under the second element, left to the second element, right to the second element, behind the second element, in front of the second element, etc.).
When the first element is described as being disposed “on” the second element, the first element may be directly or indirectly disposed on the second element. The first element being directly disposed on the second element indicates that no additional element is disposed between the first element and the second element. The first element being indirectly disposed on the second element indicates that one or more additional elements are disposed between the first element and the second element.
The term “processor” used herein may encompass any suitable processor, such as a central processing unit (“CPU”), a graphics processing unit (“GPU”), an application-specific integrated circuit (“ASIC”), a programmable logic device (“PLD”), or any combination thereof. Other processors not listed above may also be used. A processor may be implemented as software, hardware, firmware, or any combination thereof.
The term “controller” may encompass any suitable electrical circuit, software, or processor configured to generate a control signal for controlling a device, a circuit, an optical element, etc. A “controller” may be implemented as software, hardware, firmware, or any combination thereof. For example, a controller may include a processor, or may be included as a part of a processor.
The term “non-transitory computer-readable medium” may encompass any suitable medium for storing, transferring, communicating, broadcasting, or transmitting data, signal, or information. For example, the non-transitory computer-readable medium may include a memory, a hard disk, a magnetic disk, an optical disk, a tape, etc. The memory may include a read-only memory (“ROM”), a random-access memory (“RAM”), a flash memory, etc.
The term “film,” “layer,” “coating,” or “plate” may include rigid or flexible, self-supporting or free-standing film, layer, coating, or plate, which may be disposed on a supporting substrate or between substrates. The terms “film,” “layer,” “coating,” and “plate” may be interchangeable. The term “film plane” refers to a plane in the film, layer, coating, or plate that is perpendicular to the thickness direction. The film plane may be a plane in the volume of the film, layer, coating, or plate, or may be a surface plane of the film, layer, coating, or plate. The term “in-plane” as in, e.g., “in-plane orientation,” “in-plane direction,” “in-plane pitch,” etc., means that the orientation, direction, or pitch is within the film plane. The term “out-of-plane” as in, e.g., “out-of-plane direction,” “out-of-plane orientation,” or “out-of-plane pitch” etc., means that the orientation, direction, or pitch is not within a film plane (i.e., is non-parallel with a film plane). For example, the direction, orientation, or pitch may be along a line that is perpendicular to a film plane, or that forms an acute or obtuse angle with respect to the film plane. For example, an “in-plane” direction or orientation may refer to a direction or orientation within a surface plane, an “out-of-plane” direction or orientation may refer to a thickness direction or orientation non-parallel with (e.g., perpendicular to) the surface plane.
The wavelength ranges, spectra, or bands mentioned in the present disclosure are for illustrative purposes. The disclosed optical device, system, element, assembly, and method may be applied to a visible wavelength band, as well as other wavelength bands, such as an ultraviolet (“UV”) wavelength band, an infrared (“IR”) wavelength band, or a combination thereof. The term “substantially” or “primarily” used to modify an optical response action, such as “transmit,” “reflect,” “diffract,” “block” or the like that describes processing of a light means that a major portion, including all, of a light is transmitted, reflected, diffracted, or blocked, etc. The major portion may be a predetermined percentage (greater than 50%) of the entire light, such as 100%, 98%, 90%, 85%, 80%, etc., which may be determined based on specific application needs.
The in-coupling grating 135 may couple, via diffraction, the input image light 130 into the light guide 110 as an in-coupled image light 131, which may propagate toward the out-coupling grating 145 via total internal reflection (“TIR”). For example, the in-coupling grating 135 may diffract the bundles of parallel rays 130a, 130b, or 130c as the bundles of parallel rays 131a, 131b, or 131c, respectively. The out-coupling grating 145 may couple, via diffraction, the input image light 130 as a plurality of output image lights 132, which may propagate toward a plurality of exit pupils 157 positioned in an eye-box region 159 of the system 100, respectively. For example, the out-coupling grating 145 may diffract the bundle of parallel rays 131a, 131b, or 131c as a plurality of bundles of parallel rays 132a, 132b, or 132c. Each output image light 132 may include a bundle of parallel rays 132a, a bundle of parallel rays 132b, and a bundle of parallel rays 132c. Thus, the combination of light guide 110, the in-coupling grating 135, and the out-coupling grating 145 may replicate the input image light 130 at the output side to expand an effective pupil of the system 100.
The eye-box region 159 is a region in space where an eye pupil 158 of an eye 160 of a user can perceive the full extent of the virtual image delivered by the light guide 110 from the light source assembly 105. The eye-box region 159 overlaps with all, or most, of the possible positions of the eye pupil 158 of the user. This feature, referred to as “pupil expansion,” creates the effect of a full real-life image as perceived by the user, rather than a moving eye pupil characteristic provided by other viewing instruments (e.g., binoculars, microscopes, or telescopes).
The parameters of the eye-box region 159 (e.g., position, size, depth) are affected by a desirable field of view (“FOV”) and a desirable eye relief of the NED. An FOV is defined as an angular size of the image (e.g., the angular size of the diagonal of the image) as seen by the eye 160 of the user. An eye relief is a distance between the eye pupil 158 and a nearest component of the NED. The size of the eye-box region 159 may decrease as the FOV and/or the eye relief increase. A large eye-box region 159 allows the user to move the eye pupil 158 in a wider range without losing sight of the image generated by the light source assembly 105, and provides a wide range of accommodation to interpupillary distance (“IPD”) variation among different users. Typical IPD values range between 51 mm to 77 mm, depending on the age, gender, and other physiological factors of the user. Although a large eye-box region 159 provides accommodation for eye movement in a wide range and IPD variation among different users, the image light out-coupled from the light guide 110 is distributed across the entire eye-box region 159. Thus, the average light intensity provided at the eye-box region 159 may be low, and the brightness of the image perceived by the eye pupil 158 may be low. On the other hand, the area of the eye pupil 158 only occupies a small portion of the eye-box region 159. The size of the eye pupil of an average adult user may vary in a range of 4-8 millimeters (“mm”) in diameter when dilated (e.g., when in dark), or in a range of 2-4 mm in diameter when constricted (e.g., in bright light). In other words, the size of the eye pupil may vary in the range of 2-8 mm depending on the light intensity (or brightness) of the image light. Therefore, the eye pupil 158 only receives a small portion of the image light propagating through the eye-box region 159. A significant portion of the image light propagating through the eye-box region 159 may not be received by the eye pupil 158, and may be lost. Accordingly, the light guide display system 100 may not be power efficient.
In addition, in the conventional light guide display system 100, the optical efficiency at the input side of the light guide 110 (or the input efficiency of the in-coupling grating) may be affected by the in-coupling grating 135.
The in-coupled ray 131b-2 may be reflected, via TIR, at a second surface 110-2 of the light guide 110 as a ray 147, which may propagate through the light guide 110 and the volume of the in-coupling grating 135 toward an interface 135-1 of the in-coupling grating 135 and an outside environment (e.g., air). The ray 147 may be reflected, via TIR, at the interface 135-1 as a ray 148 propagating back to the volume of the in-coupling grating 135. The in-coupling grating 135 may couple, via diffraction, the ray 148 out of the light guide 110 as a ray 149. That is, the in-coupling grating 135 may couple a portion of the in-coupled image light 131 (e.g., the in-coupled ray 131b-2) out of the light guide 110, and the ray 130b-2 of the input image light 130b may not propagate inside the light guide 110 via TIR toward the out-coupling grating 145. Thus, the optical efficiency at the input side of the light guide 110 (or the input efficiency of the in-coupling grating 135) may be reduced. Accordingly, the power efficiency of the light guide display system 100 may be low. The power efficiency of the light guide display system 100 may be directly affected by the input efficiency. Thus, when the input efficiency is increased, the overall power efficiency of the light guide display system can be increased.
The present disclosure provides a light guide display system configured to provide an increased power efficiency.
A second portion 231-2 of the in-coupled image light 231 (referred to as a second in-coupled image light 231-2 for discussion purposes) may interact with the in-coupling element 235 again as propagating inside the light guide 210 via TIR. The second in-coupled image light 231-2 may be coupled out of the light guide 210 by the in-coupling element 235, as an image light 249. The recycling element 237 may be configured to couple, via deflection, the image light 249 back into the light guide 210, as a third in-coupled image light 252. In some embodiments, the recycling element 237 may be configured to deflect the image light 249 as the third in-coupled image light 252 having the same predetermined TIR propagation angle as the in-coupled image light 231 inside the light guide 210. In other words, the third in-coupled image light 252 and the first in-coupled image light 231-1 may be configured to have substantially the same TIR propagation angle inside the light guide 210. The third in-coupled image light 252 may propagate inside the light guide 210 via TIR toward the out-coupling element 245. Because the image light 249, which would otherwise be coupled out of the light guide in a conventional light guide display system (e.g., shown in
The out-coupling element 245 may couple the combination of the first in-coupled image light 231-1 and the third in-coupled image light 252 propagating inside the light guide 210 at the same TIR propagation angle out of the light guide 210 as a plurality of output image lights 232. In some embodiments, the third in-coupled image light 252 and the second in-coupled image light 231-2 may be configured to also have substantially the same light intensity, and/or the same polarization state. For discussion purposes, in the disclosed embodiments, the third in-coupled image light 252 and the second in-coupled image light 231-2 are presumed to have substantially the same light intensity, and/or the same polarization state. Thus, the combination of the first in-coupled image light 231-1 and the third in-coupled image light 252 is presumed to be substantially the same as the in-coupled image light 231. That is, through the recycling element 237, light loss otherwise caused by the in-coupling element 235 coupling a portion of the in-coupled image light 231 out of the light guide 210, is significantly reduced.
The out-coupling element 245 may consecutively couple the in-coupled image light 231, which is incident onto the different positions of the out-coupling element 245, out of the light guide 210 at different positions of the out-coupling element 245. Thus, the out-coupling element 245 may replicate the input image light 230 at the output side of the light guide 210, to expand an effective pupil of the light guide display system 200. Because the first in-coupled image light 231-1 and the third in-coupled image light 252 propagate inside the light guide 210 at the same TIR propagation angle, the out-coupled image light of the first in-coupled image light 231-1 and the out-coupled image light of the third in-coupled image light 252 may form the same image, and no ghost image may be formed by the recycled third in-coupled image light 252 at the output side of the light guide 210.
The output image lights 232 may propagate toward a plurality of exit pupils 257 positioned in an eye-box region 259 of the light guide display system 200, respectively. The exit pupil 257 may be a location where an eye pupil 258 of an eye 260 of a user is positioned in the eye-box region 259 to receive the content of a virtual image output from the display element 220. In some embodiments, the exit pupils 257 may be arranged in a one-dimensional (“1D”) or a two-dimensional (“2D”) array within the eye-box region 259. The size of a single exit pupil 257 may be larger than and comparable with the size of the eye pupil 258. The exit pupils 257 may be sufficiently spaced apart, such that when one of the exit pupils 257 substantially coincides with the position of the eye pupil 258, the remaining one or more exit pupils 257 may be located beyond the position of the eye pupil 258 (e.g., falling outside of the eye 260). In some embodiments, all of the exit pupils 257 may be simultaneously available at the eye-box region 259. In some embodiments, one or more of the exit pupils 257 (but not all of the exit pupils 257) may be simultaneously available at the eye-box region 259, e.g., depending on the position of the eye pupil 258. In some embodiments, the light guide 210 may also receive a light 255 from a real-world environment, and may combine the light 255 with the output image light 232, and deliver the combined light to the eye pupil 258.
In some embodiments, each of the in-coupling element 235, the recycling element 237, and the out-coupling element 245 may be formed or disposed at (e.g., affixed to) a first surface 210-1 or a second surface 210-2 of the light guide 210. In some embodiments, each of the in-coupling element 235, the recycling element 237, and the out-coupling element 245 may be integrally formed as a part of the light guide 210, or may be a separate element coupled to the light guide 210. In some embodiments, the in-coupling element 235 and the recycling element 237 may be disposed at different surfaces of the light guide 210. For discussion purposes, FIG. 2A shows that the recycling element 237 and the in-coupling element 235 are disposed at opposite surfaces of the light guide 210, e.g., the in-coupling element 235 is disposed at the first surface 210-1 of the light guide 210, and the recycling element 237 and the out-coupling element 245 are disposed at the second surface 210-2 of the light guide 210. The recycling element 237 may at least partially overlap with the in-coupling element 235 along the light guide 210 in the direction from the in-coupling element 235 to the out-coupling element 245 (e.g., along the x-axis direction).
In some embodiments, the in-coupling element 235, the recycling element 237, or the out-coupling element 245 may include one or more diffraction gratings, one or more cascaded reflectors, one or more prismatic surface elements, an array of holographic reflectors, or any combination thereof. In some embodiments, each of the in-coupling element 235, the recycling element 237, and the out-coupling element 245 may include one or more diffraction gratings. Examples of diffraction gratings may include a holographic polymer-dispersed liquid crystal (“H-PDLC”) grating, a surface relief grating, a volume hologram, a polarization selective grating, a liquid crystal polarization hologram (“LCPH”) grating based on liquid crystals (“LCs”) (such as a Pancharatnam-Berry phase (“PBP”) grating, a polarization volume hologram (“PVH”) grating, etc.), a polarization hologram grating based on a birefringent photo-refractive holographic material other than LCs, a metasurface grating, etc. The diffraction grating may be a reflective or transmissive grating. The diffraction grating may be a passive or active grating. The diffraction grating may be polarization sensitive (or polarization selective) or polarization insensitive (or polarization non-selective).
The display element 220 may include a display panel, such as a liquid crystal display (“LCD”) panel, a liquid-crystal-on-silicon (“LCoS”) display panel, an organic light-emitting diode (“OLED”) display panel, a micro light-emitting diode (“micro-LED”) display panel, a laser scanning display panel, a digital light processing (“DLP”) display panel, or a combination thereof. In some embodiments, the display element 220 may include a self-emissive panel, such as an OLED display panel or a micro-LED display panel. In some embodiments, the display element 220 may include a display panel that is illuminated by an external source, such as an LCD panel, an LCoS display panel, or a DLP display panel. Examples of an external source may include a laser diode, a vertical cavity surface emitting laser, a light emitting diode, or a combination thereof. The display element 220 may output an image light 229 toward the collimating lens 225. The image light 229 may represent a virtual image having a predetermined image size.
For discussion purposes,
The light guide 210 may include one or more materials configured to facilitate the TIR of the TIR propagating image light 231. The light guide 210 may include, for example, a plastic, a glass, and/or polymers. The light guide 210 may have a relatively small form factor. In some embodiments, the light guide display system 200 may include additional elements configured to redirect, fold, and/or expand the TIR propagating image light 231. For example, as shown in
In some embodiments, the redirecting element 240 may be configured to expand the TIR propagating image light 231 in a first direction (e.g., a y-axis direction in
Although the light guide 210, the in-coupling element 235, the recycling element 237, and the out-coupling element 245 are shown as having flat surfaces for illustrative purposes, any of the light guide 210, the in-coupling element 235, the recycling element 237, and the out-coupling element 245 disclosed herein may include one or more curved surfaces or may have curved shapes. The controller 215 may be communicatively coupled with the light source assembly 205, and may control the operations of the light source assembly 205 to generate an input image light. The controller 215 may include a processor or processing unit 201 and a storage device 202. The storage device 202 may be a non-transitory computer-readable medium, such as a memory, a hard disk, etc., for storing data, information, and/or computer-executable program instructions or codes.
In some embodiments, the light guided display system 200 may include a plurality of light guides 210 disposed in a stacked configuration (not shown in
For discussion purposes, in the following descriptions, the light guide display system 200 is presumed to not include the redirecting element 240. At least one of the in-coupling element 235, the recycling element 237, or the out-coupling element 245 may be a diffractive element that includes one or more diffraction gratings. For discussion purposes, a diffraction grating included in the in-coupling element 235 may be referred to as an in-coupling grating 235, a diffraction grating included in the recycling element 237 may be referred to as a recycling grating 237, and a diffraction grating included in the out-coupling element 245 may be referred to as an out-coupling grating 245.
For discussion purposes,
The second portion 231-2 of the in-coupled image light 231 (or the second in-coupled image light 231-2 represented by solid lines) may be reflected, via TIR, at the second surface 210-2 of the light guide 210 as an image light 247, which may propagate through the light guide 210 and the volume of the in-coupling grating 235 toward an interface 235-1 of the in-coupling grating 235 and an outside environment (e.g., air). The in-coupling grating 235 may be configured to transmit (rather than diffract), the image light 247 toward the interface 235-1 with negligible or zero diffraction. The image light 247 may be reflected, via TIR, at the interface 235-1 as an image light 248 propagating back to the volume of the in-coupling grating 235. The in-coupling grating 235 may be configured to couple, via diffraction, the image light 248 out of the light guide 210 as an image light 249 propagating toward the recycling grating 237.
The recycling grating 237 may be configured to direct the image light 249 back to the light guide 210 as the third in-coupled image light 252 with the predetermined TIR propagation angle inside the light guide 210. For example, as shown in
Descriptions of the same or similar elements or features can refer to the above corresponding descriptions, including those rendered in connection with
In some embodiments, the image light 262 may propagate inside the light guide 210 via TIR toward the out-coupling element 245, without interacting with the in-coupling grating 235 again. In some embodiments, the image light 262 may interact with the in-coupling grating 235 again, and the image light 262 may follow a light propagating path that is similar to the second in-coupled image light 231-2 to be coupled into the light guide 210 again.
As shown in
The in-coupling grating 235 may be a polarization selective grating. For example, the in-coupling grating 235 may be configured to substantially diffract (e.g., forwardly or backwardly) an incident light with a first polarization, while substantially transmit an incident light with a second polarization other than (e.g., orthogonal to) the first polarization, with negligible or zero diffraction. In some embodiments, the first polarization and the second polarization may be linear polarizations with orthogonal polarization directions. In some embodiments, the first polarization and the second polarization may be circular polarizations with opposite handednesses. For example, the in-coupling grating 235 may be a PVH grating configured to substantially diffract (e.g., forwardly or backwardly) a circularly incident light with a first handedness, and substantially transmit a circularly incident light with a second handedness that is opposite to the first handedness, with negligible or zero diffraction.
The retardation film 337 may be fabricated based on any suitable materials, such as liquid crystals, polymers, or plastics, etc. In some embodiments, the retardation film 337 may include at least one of an A-film, an O-film, or a biaxial film. The retardation film 337 may function as a polarization controlling or converting element, configured to control a polarization of an image light before the image light is incident onto the in-coupling grating 235.
In the embodiment shown in
A second portion 331-2 of the in-coupled image light 331 may interact with the in-coupling grating 235 again. The second portion 331-2 may also be referred to as a second in-coupled image light 331-2 for discussion purposes. For example, the second in-coupled image light 331-2 may first propagate through the light guide 210 and the retardation film 337 toward an interface 337-1 between the retardation film 337 and the outside environment (e.g., air). The second in-coupled image light 331-2 may be reflected via TIR, at the interface 337-1, as an image light 347. The retardation film 337 may be configured to provide a predetermined phase retardation to the second in-coupled image light 331-2 to re-configure, control, alter, affect, vary, change, modify, or maintain the polarization of the second in-coupled image light 331-2, such that the image light 347 output from the retardation film 337 back to the light guide 210 and the in-coupling grating 235 may have a predetermined polarization. The image light 347 may propagate through the light guide 210 and the volume of the in-coupling grating 235 toward the interface 235-1 of the in-coupling grating 235 and the outside environment (e.g., air). The image light 347 may be reflected, via TIR, at the interface 235-1 as an image light 352 propagating back to the volume of the in-coupling grating 235.
In some embodiments, the polarization of the image light 347 may not change while propagating inside the light guide 210. The retardation film 337 may be configured to provide the predetermined phase retardation to the second in-coupled image light 331-2, such that the predetermined polarization of the image light 347 output from the retardation film 337 may be the second polarization. Thus, the image light 347 and the image light 352 may have the same polarization, e.g., the second polarization. As the in-coupling grating 235 is a polarization selective grating configured to substantially diffract an incident light with the first polarization, while substantially transmit an incident light with the second polarization other than (e.g., orthogonal to) the first polarization with negligible or zero diffraction, the image light 352 having the second polarization may be transmitted through the volume of the in-coupling grating 235 toward the light guide 210, with negligible or zero diffraction.
In some embodiments, the polarization of the image light 347 may change while propagating inside the light guide 210. That is, the image light 347 and the image light 352 may have different polarizations. The predetermined polarization of the image light 347 may be configured, e.g., to be a polarization other than the second polarization, such that the image light 352 reflected from the interface 235-1 has the second polarization. Thus, the in-coupling grating 235 may transmit the image light 352 toward the light guide 210, with negligible or zero diffraction.
For example, in some embodiments, the in-coupling grating 235 may be a PVH grating configured to substantially diffract a left-handed circularly polarized (“LHCP”) light, and substantially transmit a right-handed circularly polarized (“RHCP”) light with negligible or zero diffraction. Thus, the predetermined phase retardation provided to the second in-coupled image light 331-2 by the retardation film 337 may be configured, such that the image light 352 reflected from the interface 235-1 may be an RHCP light. Thus, the in-coupling grating 235 may transmit the image light (e.g., RHCP light) 352 toward the light guide 210, with negligible or zero diffraction.
As the retardation film 337 does not change the TIR propagation angle of the second in-coupled image light 331-2, the image light 352 may propagate inside the light guide 210, via TIR, toward the out-coupling element 245, at the same predetermined TIR propagation angle. The image light 352 may also be referred to as a third in-coupled image light 352 for discussion purposes. Thus, as the in-coupling grating 235 substantially transmit the image light 352 toward the light guide 210 (rather than diffract the image light 352 out of the light guide 210), the optical efficiency at the input side of the light guide 210 (or the input efficiency of the in-coupling grating 235) is increased. Accordingly, the power efficiency of the light guide display system 300 is increased.
For discussion purposes, in the disclosed embodiments, the combination of the first in-coupled image light 331-1 and the third in-coupled image light 352 is presumed to be substantially the same as the in-coupled image light 331. The out-coupling element 245 may couple the in-coupled image light 331 out of the light guide 210 as a plurality of output image lights 332. The out-coupling element 245 may consecutively couple the in-coupled image light 331, which is incident onto the different positions of the out-coupling element 245, out of the light guide 210 at different positions of the out-coupling element 245. Thus, the out-coupling element 245 may replicate the input image light 230 at the output side of the light guide 210, to expand an effective pupil of the light guide display system 300. The plurality of output image lights 332 may propagate toward the plurality of exit pupils 257 positioned in the eye-box region 259 of the light guide display system 300, respectively. Because the first in-coupled image light 331-1 and the third in-coupled image light 352 propagate inside the light guide 210 at the same TIR propagation angle, the out-coupled image light of the first in-coupled image light 331-1 and the out-coupled image light of the third in-coupled image light 352 may form the same image, and no ghost image may be formed at the output side of the light guide 210.
For example, in some embodiments, the in-coupling grating 235 may be a PVH grating configured to substantially diffract an LHCP light, and substantially transmit an RHCP light with negligible or zero diffraction. Thus, the predetermined phase retardation provided to the second in-coupled image light 331-2 by the retardation film 337 may be configured, such that the image light 362 reflected from the interface 235-1 may be an RHCP light. Thus, the in-coupling grating 235 may transmit the image light (e.g., RHCP light) 362 toward the light guide 210, with negligible or zero diffraction.
As the retardation film 337 does not change the TIR propagation angle of the second in-coupled image light 331-2, the image light 362 may propagate inside the light guide 210, via TIR, toward the out-coupling element 245, with the predetermined TIR propagation angle. The image light 362 may also be referred to as a third in-coupled image light 362 for discussion purposes. Thus, the optical efficiency at the input side of the light guide 210 (or the input efficiency of the in-coupling grating 235) is increased. Accordingly, the power efficiency of the light guide display system 350 is increased.
For discussion purposes, in the disclosed embodiments, the combination of the first in-coupled image light 331-1 and the third in-coupled image light 362 is presumed to be substantially the same as the in-coupled image light 331. The out-coupling element 245 may couple the in-coupled image light 331 (e.g., the combination of the first in-coupled image light 331-1 and the third in-coupled image light 362) out of the light guide 210 as a plurality of output image lights 332 toward the plurality of exit pupils 257, respectively.
In conventional technology, an out-coupling element (e.g., the size, the structure) is designed for a full, large eye-box, which may cause energy waste and more rainbow effects. In some embodiments, the present disclosure provides a light guide display system configured to provide an active eye-box. The disclosed light guide display system may include a light guide (or a light guide stack), an in-coupling element, one or more redirecting elements, an out-coupling element, and a controller configured to control at least one of the in-coupling element, the one or more redirecting elements, and the out-coupling element. The out-coupling element may include a plurality of selectively activatable (i.e., active) out-coupling gratings. When a plurality of redirecting elements are included, the redirecting elements may be disposed at different portions of the light guide, and each redirecting element may redirect an image light received from the in-coupling element to a specific active out-coupling grating (or multiple specific active out-coupling gratings) included in the out-coupling element. The controller may control the in-coupling element to couple an input image light into the light guide in different, selectable propagating directions inside the light guide, based on eye-tracking information obtained by an eye-tracking system. For example, the controller may control the in-coupling element such that the input image light is coupled into the light guide as an in-coupled image light propagating in a direction toward one of the one or more redirecting elements via TIR, or propagating in a direction toward one or more active out-coupling gratings included in the out-coupling element via TIR. When the input image light is coupled into the light guide as the in-coupled image light propagating in the direction toward one of the one or more redirecting elements via TIR, the redirecting element may direct the in-coupled image light to one or more specific active out-coupling gratings included in the out-coupling element, such that the one or more specific active out-coupling gratings may couple the in-coupled image light out of the light guide to a small eye-box region, which is part of the full eye-box, rather than to the full eye-box. When the input image light is coupled into the light guide as the in-coupled image light propagating in the direction toward one or more specific active out-coupling gratings included in the out-coupling element via TIR, the one or more specific active out-coupling gratings may couple the in-coupled image light out of the light guide to a small eye-box region, which is part of the full eye-box, rather than to the full eye-box. The user's eye receives the image light from the small eye-box region, rather than from the full large eye-box. Thus, the light guide display system can increase the intensity of the image light received by the eye pupil, reduce the loss of the image light outside of the eye pupil, increase the power efficiency of the light guide display system, and reduce the rainbow effect in a see-though view.
The light guide display system 401 may be configured to project an image light (that forms computer-generated virtual images) into a display window in a field of view (“FOV”). The eye tracking system 450 may be configured to provide eye-tracking information, based on which a position of the eye pupil 258 of the user of the light guide display system 401 may be determined. The light guide display system 401 may be configured to guide the image light 230 output from the light source assembly 205 to an eye-box 459 where the eye pupil 258 of the user is positioned. The location, the size, and/or the shape of the eye-box 459 may vary according to the eye-tracking information. The location of the eye-box 459 may be dynamically aligned with the position of the eye pupil 258. The size of the eye-box 459 may be comparable with (e.g., the same as or slightly larger than) the size of the eye pupil. The size of the eye pupil of an average adult user may vary in a range of 4-8 millimeters (“mm”) in diameter when dilated (e.g., when in dark), or vary in a range of 2-4 mm in diameter when constricted (e.g., in bright light). In other words, the size of the eye pupil may vary in the range of 2-8 mm depending on the light intensity (or brightness) of the received light. Such an eye-box 459 may be referred to as an active eye-box.
As shown in
In some embodiments, an active grating may be directly driven by an external field, e.g., an external electric field. In some embodiments, the active grating may be controlled or switched, e.g., by the controller 215, between operating in a diffraction state to diffract an incident light, and operating in a non-diffraction state to transmit the incident light with substantially zero or negligible diffraction. In some embodiments, the active grating that operates in the diffraction state may provide a fixed diffraction angle to an incident light with a fixed incidence angle. In some embodiments, the active grating that operates in the diffraction state may provide a tunable diffraction angle to the incident light with a fixed incidence angle. For example, the active grating may operate in different diffraction states under different driving voltages, thereby diffracting the incident light with the fixed incidence angle at different diffraction angles. In some embodiments, when the driving voltage applied to the active grating is changed, the grating period of the active grating may be changed, such that the active grating may diffract the incident light with the fixed incidence angle at different diffraction angles. In some embodiments, when the driving voltage applied to the active grating is changed, a modulation of the refractive index of the active grating may be changed, such that the active grating may diffract the incident light with the fixed incidence angle to different diffraction angles.
The active grating may be polarization sensitive (or polarization selective) or polarization insensitive (or polarization non-selective). The active grating may be a reflective grating or a transmissive grating. The active grating may be fabricated based on any suitable materials. In some embodiments, the active grating fabricated based on active liquid crystals (“LCs”) may include active LC molecules, orientations of which may be changeable by the external field (e.g., external electric field). Examples of active gratings may include, but not be limited to, holographic polymer-dispersed liquid crystal (“H-PDLC”) gratings, surface relief gratings provided (e.g., filled) with active LCs, Pancharatnam-Berry phase (“PBP”) gratings based on active LCs, polarization volume holograms (“PVHs”) based on active LCs, etc.
In some embodiments, a passive grating may not be directly driven by an external field, e.g., an external electric field. The passive grating may be polarization sensitive (or polarization selective) or polarization insensitive (or polarization non-selective). The passive grating may be a reflective grating or a transmissive grating. The passive grating may be fabricated based on any suitable materials. In some embodiments, the passive grating fabricated based on passive LCs may include passive LC molecules, orientations of which may not be changeable by the external field (e.g., external electric field). Examples of passive gratings may include, but not be limited to, H-PDLC gratings, surface relief gratings provided (e.g., filled) with passive LCs, PBP gratings based on passive LCs, PVH gratings based on passive LCs, etc.
Referring to
For example, referring to
Referring to
Referring to
Referring to
The eye tracking system 450 may be configured to provide eye tracking information, based on which a position of the eye pupil 258 of the user of the light guide display system 401 may be determined. Any suitable eye tracking system 450 may be used. The eye tracking system 450 may include, e.g., one or more light sources 415 configured to illuminate one or both eyes 260 of the user, and one or more optical sensors (e.g., cameras) 410 configured to capture images of one or both eyes 260. The eye tracking system 450 may be configured to track a position, a movement, and/or a viewing direction of the eye pupil 258. In some embodiments, the eye tracking system 450 may determine or detect a position and/or a movement of the eye pupil 258 up to six degrees of freedom for each eye 260 (i.e., 3D positions, roll, pitch, and yaw) based on captured image data of the eye pupil 258. In some embodiments, the eye tracking system 450 may measure a pupil size of the eye pupil 258.
In some embodiments, the controller 215 may be electrically coupled with, and may control, various devices in the eye tracking system 450. In the embodiment shown in
In some embodiments, the controller 215 may control, based on the eye tracking information, the gratings included in at least one of the in-coupling element 435, the out-coupling element 445, or the redirecting elements 405-1 and 405-2 to direct the image light 230 emitted by the light source assembly 205 to the eye-box 459, which may be dynamically aligned with the eye pupil 258. In the embodiment shown in
The remaining one or more of the out-coupling gratings 461 to 469 controlled to operate in the non-diffraction state may function as a substantially optically uniform plate for the in-coupled image light 431-1, 431-4, or 431-5. That is, the remaining one or more of the out-coupling gratings 461 to 469 operating in the non-diffraction state may transmit the in-coupled image light 431-1, 431-4, or 431-5 therethrough with negligible or no diffraction. To selectively control an out-coupling grating to operate in the diffraction state, or to selectively control the out-coupling grating to operate in the non-diffraction state, the controller 215 may either switch the out-coupling grating from the diffraction state to the non-diffraction state, or from the non-diffraction state to the diffraction state, or maintain the diffraction state or the non-diffraction state, depending on the state of the out-coupling grating at a preceding time instance or time duration.
The controller 215 may dynamically adjust the size, shape and/or location of the eye-box 459 based on the real time eye tracking information, including, e.g., the size of the eye pupil 258, the position of the eye pupil 258, the moving direction of the eye pupil 258, the viewing direction of the eye pupil 258, or any suitable combination thereof. For example, at different time instances, based on the eye tracking information obtained in real time, the controller 215 may dynamically control different gratings (or different combinations of the gratings) included in at least one of the in-coupling element 435, the out-coupling element 445, or the redirecting elements 405-1 and 405-2 to direct the image light 230 of a predetermined FOV to the eye-box 459 at a different location and/or with a different size and/or shape.
Referring to
Thus, the in-coupling grating 435 that operates in the first diffraction state and the out-coupling grating 464 that operates in the diffraction state may direct the image light 230 to the eye-box 459 at the first position where the eye pupil 258 is located. The size and location of the eye-box 459 at the first position may be maintained for a first time period until a change in the eye tracking information of the eye pupil 258 is detected. The change may be a change in the size of the eye pupil 258, a change in the position of the eye pupil 258, a change in the moving direction of the eye pupil 258, and/or a change in the viewing direction of the eye pupil 258.
Although not shown in
Referring to
Based on the position information of the eye pupil 258, the controller 215 may selectively control the out-coupling grating 469 of the out-coupling element 445 to operate in the diffraction state, and selectively control the remaining out-coupling gratings 461 to 468 to operate in the non-diffraction state. The out-coupling grating 469 that operates in the diffraction state may couple, via diffraction, the in-coupled image light 431-4 incident thereon as an output image light 432-2 that provides or forms the eye-box 459 at the second position where the eye pupil 258 is located. The out-coupling gratings 467 and 468 that operate in the non-diffraction state may transmit the in-coupled image light 431-4 therethrough with negligible or no diffraction. The output image light 432-2 may have the same FOV as the input image light 230. Thus, the eye pupil 258 located within the eye-box 459 at the second position may observe full content of an image generated by the light source assembly 205.
Thus, the in-coupling grating 435 that operates in the second diffraction state and the out-coupling grating 459 that operates in the diffraction state may direct the image light 230 to the eye-box 459 at the second position where the eye pupil 258 is located. In some embodiments, at least one of the location, shape, and/or size of the eye-box 459 at the second time instance may be different from the at least one of the location, shape, and/or size of the eye-box 459 at the first time instance. The size and location of the eye-box 459 at the second position may be maintained for a second time period until a change in the eye tracking information of the eye pupil 258 is detected.
Referring to
Based on the position information of the eye pupil 258, the controller 215 may selectively control the out-coupling grating 462 of the out-coupling element 445 to operate in the diffraction state, and selectively control the remaining out-coupling gratings 461, and 463 to 469 to operate in the non-diffraction state. The out-coupling grating 462 that operates in the diffraction state may couple, via diffraction, the in-coupled image light 431-5 incident thereon as an output image light 432-3 that provides or forms the eye-box 459 at the third position where the eye pupil 258 is located. The out-coupling gratings 461 and 463 that operate in the non-diffraction state may transmit the in-coupled image light 431-5 therethrough with negligible or no diffraction. The output image light 432-3 may have the same FOV as the input image light 230. Thus, the eye pupil 258 located within the eye-box 459 at the third position may observe full content of an image generated by the light source assembly 205.
Thus, the in-coupling grating 435 that operates in the third diffraction state and the out-coupling grating 462 that operates in the diffraction state may direct the image light 230 to the eye-box 459 at the third position where the eye pupil 258 is located. In some embodiments, at least one of the location, shape, and/or size of the eye-box 459 at the third time instance may be different from the at least one of the location, shape, and/or size of the eye-box 459 at the second time instance. The size and location of the eye-box 459 at the third position may be maintained for a third time period until a change in the eye tracking information of the eye pupil 258 is detected.
Referring to
Compared to the conventional light guide display system 100 shown in
For illustrative purposes,
For illustrative purposes,
In some embodiments, an active grating configured to operate in a plurality of (e.g., two) different diffraction states (e.g., at different driving voltages) to diffract the same incident light at a plurality of (e.g., three) different diffraction angles may be replaced by a plurality of (e.g., three) active gratings. Each of the plurality of (e.g., three) active gratings may be controlled or switched, e.g., by the controller 215, between operating in a diffraction state to diffract an incident light, and operating in a non-diffraction state to transmit the incident light with substantially zero or negligible diffraction. The plurality of (e.g., three) active gratings that operates in the diffraction state may diffract the same incident light at a plurality of (e.g., three) different diffraction angles.
As shown in
Based on the eye tracking information, the controller 215 may control one of the in-coupling gratings 435-1, 435-2, and 435-3 to operate in the diffraction state, and the remaining of the in-coupling gratings 435-1, 435-2, and 435-3 to operate in the non-diffraction state. The in-coupling gratings 435-1, 435-2, and 435-3 may be configured (e.g., by configuring the grating periods, or modulations of the refractive indices, etc.), such that the in-coupling gratings 435-1, 435-2, and 435-3 operating in the diffraction state during different time instances may diffract the in-coupled image light 231 at different diffraction angles.
For example, when the controller 215 controls the in-coupling grating 435-1 to operate in the diffraction state, and the in-coupling grating 435-2 and 435-3 to operate in the non-diffraction state, the in-coupling grating 435-1 may couple, via diffraction, the input image light 230 as an in-coupled image light 491-1 propagating toward the out-coupling element 445, e.g., along the x-axis direction. The in-coupled image light 491-1 may have a predetermined TIR propagation angle inside the light guide 210.
For example, when the controller 215 controls the in-coupling grating 435-2 to operate in the diffraction state, and the in-coupling grating 435-1 and 435-3 to operate in the non-diffraction state, the in-coupling grating 435-2 may couple, via diffraction, the input image light 230 as the in-coupled image light 491-2 propagating toward the redirecting grating 405-2. The redirecting grating 405-2 may be configured to diffract the in-coupled image light 491-2 as an in-coupled image light having the same predetermined TIR propagation angle as the in-coupled image light 491-1, and propagating toward the out-coupling element 445 along the same direction as the in-coupled image light 491-1, e.g., along the x-axis direction.
For example, when the controller 215 controls the in-coupling grating 435-3 to operate in the diffraction state, and the in-coupling grating 435-1 and 435-2 to operate in the non-diffraction state, the in-coupling grating 435-3 may couple, via diffraction, the input image light 230 as the in-coupled image light 491-3 propagating toward the redirecting grating 405-1. The redirecting grating 405-1 may be configured to diffract the in-coupled image light 491-3 as an in-coupled image light having the same predetermined TIR propagation angle as the in-coupled image light 491-1, and propagating toward the out-coupling element 445 along the same direction as the in-coupled image light 491-1, e.g., along the x-axis direction.
Thus, the redirecting grating 405-1 or 405-2 may direct the in-coupled image light received from the in-coupling grating 435 to propagate toward a selected portion (e.g., one of the row including gratings 461 to 463, and the row including the gratings 467 to 469) of the out-coupling element 445, which may otherwise not receive the in-coupled image light output from the in-coupling grating 435. In other words, the redirecting grating 405-1 or 405-2 may provide a local illumination to the selected portion of the out-coupling element 445. Based on the eye tracking information, the controller 215 may control one or more out-coupling gratings located in the selected portion of the out-coupling element 445 to operate in the diffraction state to couple the in-coupled image light directed thereto out of the light guide 210, and control the remaining one or more out-coupling gratings located in the selected portion of the out-coupling element 445 to operate in the non-diffraction state.
The elements in the light guide display systems and the features of the light guide display systems as described in various embodiments may be combined in any suitable manner. For example, in some embodiments, the light guide 210 included in the light guide display system 401 shown in
As shown in
In addition, the light guide 210 included in the light guide display system 501 may also be coupled with one or more retardation films 337. The in-coupling grating 435 may be a polarization selective grating configured to substantially diffract (e.g., forwardly or backwardly) an incident light with a first polarization, while substantially transmit an incident light with a second polarization other than (e.g., orthogonal to) the first polarization, with negligible or zero diffraction. In some embodiments, the in-coupling grating 435 may be a PVH grating configured to substantially diffract an LHCP (or an RHCP) light, and substantially transmit an RHCP (or LHCP) light with negligible or zero diffraction.
The retardation film 337 may be configured to control a polarization of the in-coupled image light 531 output from the retardation film 337 toward the in-coupling grating 435. Thus, when the in-coupled image light 531 output from the retardation film 337 interacts with the in-coupling grating 435, the in-coupled image light 531 may be transmitted through the volume of the in-coupling grating 435 with negligible or zero diffraction, instead of being diffracted out of the light guide 210. For example, when the in-coupling grating 435 is a PVH grating configured to substantially diffract an LHCP light, and substantially transmit an RHCP light with negligible or zero diffraction, the retardation film 337 may configure the in-coupled image light 531 output from the retardation film 337 and propagating toward the in-coupling grating 435 to be an RHCP light. Thus, when the in-coupled image light 531 (e.g., RHCP light) output from the retardation film 337 interacts with the in-coupling grating 435, the in-coupled image light 531 (e.g., RHCP light) may be substantially transmitted through the volume of the in-coupling grating 435, with negligible or zero diffraction. Thus, the optical efficiency at the input side of the light guide 210 (or the input efficiency of the in-coupling grating 435) may be improved. Accordingly, the power efficiency of the optical system 500 may be further improved.
As shown in
In addition, the light guide 210 included in the light guide display system 561 may also be coupled with one or more recycling elements 237. In some embodiments, a portion of the in-coupled image light 571 may interact with the in-coupling grating 435 again as propagating inside the light guide 210 via TIR, and may be coupled out of the light guide 210 by the in-coupling grating 435. The recycling element 237 may be configured to couple, via deflection, the portion of the in-coupled image light 571 that has been coupled out of the light guide 210 by the in-coupling grating 435, back into the light guide 210. Thus, the optical efficiency at the input side of the light guide 210 (or the input efficiency of the in-coupling grating 435) may be improved. Accordingly, the power efficiency of the optical system 560 may be further improved.
Although not shown, the method 601 may include other steps and processes described above in connection with other figures. In some embodiments, the recycling element may include a recycling grating. The method 601 may also include diffracting, by the recycling grating, the third image light back into the light guide as the fourth image light having the same TIR propagation angle inside the light guide as the second image light. The portion of the second image light that propagates out of the light guide as the third image light may be a first portion. A second portion of the second image light may propagate inside the light guide via TIR. In some embodiments, the method 601 may also include coupling, by an out-coupling element coupled with the light guide, the fourth image light and the second portion of the second image light out of the light guide as an output image light.
In some embodiments, the in-coupling grating and the retardation film coupled with the light guide may be disposed at the same surface of the light guide, and the in-coupling grating may be disposed between the light guide and the retardation film. In some embodiments, the in-coupling grating and the retardation film coupled with the light guide may be disposed at opposite surfaces of the light guide. Although not shown, the method 602 may include other steps or processes described in connection with other figures. In some embodiments, the method 602 may include transmitting, by the volume of the in-coupling grating, the third image light having the second polarization as a fifth image light propagating toward an interface between the in-coupling grating and an outside environment. In some embodiments, the method 602 may include, totally internally reflecting, by the interface between the in-coupling grating and the outside environment, the fifth image light as the fourth image light propagating back to the volume of the in-coupling grating. In some embodiments, the method 602 may include, transmitting, by the volume of the in-coupling grating, the fourth image light into the light guide.
In some embodiments, the polarization of the image light propagation inside the light guide may be changed. In some embodiments, the method 602 may also include converting, by the retardation film coupled with the light guide, the second image light incident thereon as a third image light having a predetermined polarization. The method 602 may also include reflecting, by the in-coupling grating, the third image light propagating through a volume of the in-coupling grating at a surface of the in-coupling grating as a fourth image light having a second polarization that is orthogonal to the first polarization. The method 602 may also include, transmitting, by the volume of the in-coupling grating, the fourth image light having the second polarization as a fifth image light propagating inside the light guide via TIR.
Although not shown, the method 603 may include other steps or processes described above in connection with other figures. For example, in some embodiments, the method 603 may include, based on eye-tracking information, controlling, by the controller, the in-coupling element to selectively direct the second image light to propagate in one of the plurality of selectable directions inside the light guide. The method 603 may include, based on the eye-tracking information, controlling, by the controller, the out-coupling element to selectively activate one or more out-coupling gratings in the predetermined portion of the out-coupling element to couple the second image light received from the in-coupling element or from the redirecting element out of the light guide as an output image light propagating toward a small portion of a full eye-box. The small portion of the full eye-box may be aligned with a position of an eye pupil of a user, and may have a size that may be comparable with and slightly larger than the size of the eye pupil.
In some embodiments, the plurality of selectable directions may include a plurality of directions from the in-coupling element to a plurality of redirecting elements. The controller may control the in-coupling element such that the second image light is directed from the in-coupling element to one of the redirecting elements in one of the selectable directions. The redirecting element may redirect the second image light to one of the plurality of predetermined portions of the out-coupling element. The out-coupling element may couple the second image light out of the light guide, for example, to a small portion of a full eye-box corresponding to an eye pupil of a user. In some embodiments, the plurality of selectable directions may include one or more directions from the in-coupling element to one or more redirecting elements, and one or more directions from the in-coupling element to one or more predetermined portions of the out-coupling element. The controller may control the in-coupling element such that the second image light propagates from the in-coupling element either to one of the redirecting elements, which then redirects the second image light to one of the predetermined portions of the out-coupling element, or directly propagates from the in-coupling element to a predetermined portion of the out-coupling element.
The disclosed optical systems (e.g., light guide display systems) and method for providing an increased power efficiency (e.g., providing an increased input efficiency and/or an active eye-box) may be implemented in various systems, e.g., a near-eye display (“NED”), a head-up display (“HUD”), a head-mounted display (“HMD”), smart phones, laptops, or televisions, etc. In addition, the light guide display systems shown in the figures are for illustrative purposes to explain the mechanism for providing an increased power efficiency. The mechanism for providing an increased power efficiency may be applicable to any suitable display systems other than the disclosed light guide display systems. The gratings are for illustrative purposes. Any suitable light deflecting elements (e.g., non-switchable light deflecting elements, indirectly switchable light deflecting elements, and/or directly switchable light deflecting elements) may be used and configured to provide the increased power efficiency, following the same or similar design principles described herein with respect to the gratings.
A non-switchable light deflecting element may be a passive light deflecting element. In some embodiments, the passive light deflecting element may be polarization non-selective (or polarization independent). An indirectly switchable light deflecting element may be a passive light deflecting element that is polarization selective. The indirectly switchable light deflecting element may be switchable between different operating states when the polarization of the input light is switched by a polarization switch coupled with the passive light deflecting element. A directly switchable light deflecting element may be switchable between different operating states when a driving voltage applied to the directly switchable light deflecting element is controlled to be different voltages.
For example, the light deflecting element may include a polarization selective grating or a holographic element that includes sub-wavelength structures, liquid crystals, a photo-refractive holographic material, or a combination thereof. In some embodiments, the polarization non-selective light deflecting element may also be implemented and configured to provide an increased output pixel density. In some embodiments, the light deflecting elements may include diffraction gratings, cascaded reflectors, prismatic surface elements, an array of holographic reflectors, or a combination thereof. The controller may be configured to configure a light deflecting element to operate at a light deflection state to deflect an input light to change a propagating direction of the input light, or operate at a light non-deflection state in which the light deflecting element may not change the propagating direction of the input light.
The left-eye and right-eye display systems 710L and 710R may include image display components configured to project computer-generated virtual images into left and right display windows 715L and 715R in a field of view (“FOV”). The left-eye and right-eye display systems 710L and 710R may be any suitable display systems. In some embodiments, the left-eye and right-eye display systems 710L and 710R may include one or more optical systems (e.g., light guide display systems) disclosed herein, such as the light guide display system 200 shown in
As shown in
The object tracking system 790 may include an IR light source 791 configured to illuminate the eye 260 and/or the face, a deflecting element 792 (such as a grating), and an optical sensor 793 (such as a camera). The deflecting element 792 may deflect (e.g., diffract) the IR light reflected by the eye 260 toward the optical sensor 793. The optical sensor 793 may generate a tracking signal relating to the eye 260. The tracking signal may be an image of the eye 260. A controller (not shown), such as the controller 215, may control various optical elements, such as an active in-coupling element, an active out-coupling element, an active dimming element, etc., based on eye-tracking information obtained from analysis of the image of the eye 260. In some embodiments, the object tracking system 790 may include elements similar to the eye tracking system 450 shown in
In some embodiments, the NED 700 may include an adaptive or active dimming element configured to dynamically adjust the transmittance of lights reflected by real-world objects, thereby switching the NED 700 between a VR device and an AR device or between a VR device and an MR device. In some embodiments, along with switching between the AR/MR device and the VR device, the adaptive dimming element may be used in the AR and/MR device to mitigate differences in brightness of lights reflected by real-world objects and virtual image lights.
As shown in
In some embodiments, the active grating 801 may include a surface relief grating (“SRG”) 805 disposed at (e.g., bonded to or formed on) a surface of the lower substrate 815 facing the upper substrate 810. The SRG 805 may include a plurality of microstructures 805a, with sizes in micron levels or nano levels, which define or form a plurality of grooves 806. The microstructures 805a are schematically illustrated as solid black longitudinal structures, and the grooves 806 are shown as white portions between the solid black portions. The number of the grooves 806 may be determined by the grating period and the size of the SRG 805. The grooves 806 may be at least partially provided (e.g., filled) with a birefringent material 850. Optically anisotropic molecules 820 of the birefringent material 850 may have an elongated shape (represented by white rods in
When the grooves 806 have a substantially rectangular prism shape, or a longitudinal shape, the groove direction may be a groove length direction. In some embodiments, the grooves 806 may have other shapes. Accordingly, the groove direction may be other suitable directions. The birefringent material 850 may be an active, optically anisotropic material, such as active liquid crystals (“LCs”) with LC directors reorientable by an external field, e.g., the electric field provided by the power source 840. The optically anisotropic molecules 820 of the birefringent material 850 may also be referred to as LC molecules 820. The active LCs may have a positive or negative dielectric anisotropy.
The SRG 805 may be fabricated based on an organic material, such as amorphous or liquid crystalline polymers, or cross-linkable monomers including those having LC properties (reactive mesogens (“RMs”)). In some embodiments, the SRG 805 may be fabricated based on an inorganic material, such as metals or oxides used for manufacturing metasurfaces. The materials of the SRG 805 may be isotropic or anisotropic. In some embodiments, the SRG 805 may provide an alignment for the birefringent material 850. That is, the SRG 805 may function as an alignment layer to align the birefringent material 850. In some embodiments, the optically anisotropic molecules 820 may be aligned within the grooves 806 by a suitable alignment method, such as by a mechanical force (e.g., a stretch), a light (e.g., through photoalignment), an electric field, a magnetic field, or a combination thereof.
For illustrative purposes,
In some embodiments, the alignment of the birefringent material 850 may be provided by one or more alignment structures (e.g., alignment layers) other than by the SRG 805. An alignment structure may be disposed at the substrate 810 and/or 815 (e.g., two alignment layers may be disposed at the respective opposing surfaces of the substrates 810 and 815). In some embodiments, the alignment structures provided at both of the substrates 810 and 815 may provide parallel planar alignments or hybrid alignments. For example, the alignment structure disposed at one of the substrates 810 and 815 may be configured to provide a planar alignment, and the alignment structure disposed at the other one of the substrates 810 and 815 may be configured to provide a homeotropic alignment. In some embodiments, the alignment of the birefringent material 850 may be provided by both the SRG 805 and one or more alignment structures (e.g., alignment layers) disposed at the substrate 810 and/or 815.
In some embodiments, as shown in
For example, referring to
In some embodiments, the active grating 801 may be an active grating, which may be directly switchable between a diffraction state (or an activated state) and a non-diffraction state (or a deactivated state) by an external field, e.g., an external electric field provided by the power source 840. For example, the active grating 801 may include electrodes (not shown) disposed at the upper and lower substrate 810 and 815, and the power source 840 may be electrically coupled with the electrodes to provide the electric field to the active grating 801. The controller 215 may control an output (e.g., a voltage and/or current) of the power source 840. For discussion purposes, the voltage is used as an example output of the power source 840. By controlling the voltage output by the power source 840, the controller 215 may control the switching of the active grating 801 between the diffraction state and the non-diffraction state. For example, the controller 215 may control the voltage supplied by the power source 840 to switch the active grating 801 between the diffraction state and the non-diffraction state. When the active grating 801 operates in the diffraction state, the controller 215 may adjust the voltage supplied by the power source 840 to the electrodes to adjust the diffraction efficiency.
In some embodiments, the controller 215 may control the voltage supplied by the power source 840 to be lower than or equal to a threshold voltage, thereby configuring the active grating 801 to operate in the diffraction state (or activated state). In some embodiments, the threshold voltage may be determined by physical parameters of the active grating 801. When the voltage is lower than or equal to the threshold voltage, the electric field generated by the supplied voltage may be insufficient to reorient the LC molecules 820. When the controller 215 controls the supplied voltage to be higher than the threshold voltage (and sufficiently high) to reorient the LC molecules 820 to substantially follow (e.g., be parallel with) the direction of the electric field, the active grating 801 may operate in the non-diffraction state (or deactivated state).
As shown in
As shown in
When the voltage is sufficiently high, as shown in
In the embodiment shown in
The substrate 906 provided with the electrode layer 908 may also be provided with a low refractive index layer 910. In some embodiments, the low refractive index layer 910 may be configured to have a refractive index that is less than a refractive index np of the material of the polymer matrix 904. For example, the refractive index np of the material of the polymer matrix 904 may be about 1.3, and the refractive index of the low refractive index layer 910 may be less than 1.3 and close to the refractive index of air. For discussion purposes,
Referring to
The LC droplets 902 are usually small (dimensions in sub-wavelength ranges) so that scattering due to refractive index mismatch of the LC and polymer may be minimized, and phase modulation may play a primary role. In other words, H-PDLC may belong to a class of nano-PDLC. The haze of the H-PDLC grating 901 caused by the scattering of the LC droplets 902 may be substantially small.
For an input light linearly polarized in a direction (e.g., a y-axis direction) perpendicular to the predetermined alignment direction (e.g., an x-axis direction) of the H-PDLC grating 901, due to the substantial match between the refractive indices no and ng, the H-PDLC grating 901 may function as a substantially optically uniform plate. That is, the H-PDLC grating 901 may not diffract, but may transmit the input light linearly polarized in the direction (e.g., a y-axis direction) perpendicular to the predetermined alignment direction (e.g., an x-axis direction).
The controller 215 may control an output (e.g., a voltage and/or current) of the power source 840. For example, by controlling the voltage output by the power source 840, the controller 215 may control the switching of the H-PDLC grating 901 between the diffraction state and the non-diffraction state. When the H-PDLC grating 901 operates in the diffraction state, the controller 215 may adjust the voltage supplied by the power source 840 to adjust the diffraction angle. In some embodiments, the controller 215 may configure the active grating 901 to operate in the diffraction state by controlling a voltage supplied by the power source 840 to be lower than or equal to a threshold voltage. When the voltage is lower than or equal to the threshold voltage, the electric field generated by the supplied voltage may be insufficient to reorient the LC molecules 920 in the LC droplets 902. In some embodiments, the controller 215 may configure the H-PDLC grating 901 to operate in the non-diffraction state by controlling the supplied voltage to be higher than the threshold voltage (and sufficiently high) to reorient the LC molecules 920 to be parallel with the direction of the electric field.
In the embodiment shown in
In the embodiment shown in
In some embodiments, when the active grating 901 is implemented in a light guide display system disclosed herein as an in-coupling grating, an out-coupling grating, or a redirecting grating, the lower substrate 906 may be a light guide or a part of the light guide in a light guide display system disclosed herein. That is, the polymer matrix 904 embedded with the LC droplets 902 may be disposed between the upper substrate 906 (that is provided with the electrode layer 908 and the low refractive index layer 910), and the light guide of the light guide display system.
For discussion purposes,
An LCPH grating (e.g., a PBP grating, a PVH grating, etc.) may be formed by a thin layer of one or more birefringent materials with intrinsic or induced (e.g., photo-induced) optical anisotropy (referred to as an optically anisotropic layer or a birefringent medium layer). A desirable predetermined grating phase profile may be directly encoded into local orientations of the optic axis of the birefringent medium layer. An LCPH grating described herein may be fabricated based on various methods, such as holographic interference, laser direct writing, ink-jet printing, and various other forms of lithography. Thus, a “hologram” described herein is not limited to creation by holographic interference, or “holography.”
An LCPH grating may be switchable between a diffraction state and a non-diffraction state. In some embodiments, an LCPH grating operating in the diffraction state may provide a tunable diffraction angle to an incident light. An LCPH grating may be transmissive or reflective. An LCPH grating may be polarization selective or polarization non-selective. An LCPH grating may be implemented into a light guide display system disclosed herein as an in-coupling grating, an out-coupling grating, or a redirecting grating.
In some embodiments, the controller 215 may control the LCPH grating 1005 to operate in the diffraction state by controlling a voltage supplied by the power source 840 to be lower than or equal to a threshold voltage. When the voltage is lower than or equal to the threshold voltage, the electric field generated by the supplied voltage may be insufficient to reorient the LC molecules in the LCPH grating 1005. As shown in
In some embodiments, the controller 215 may control the LCPH grating 1005 to operate in the non-diffraction state by controlling the supplied voltage to be higher than the threshold voltage (and sufficiently high) to reorient the LC molecules LCPH grating 1005 to be parallel with the direction of the electric field. As shown in
In some embodiments, the controller 215 may configure the LCPH grating 1050 to operate in the diffraction state by controlling a voltage supplied by the power source 840 to be lower than or equal to a threshold voltage. When the voltage is lower than or equal to the threshold voltage, the electric field generated by the supplied voltage may be insufficient to reorient the LC molecules in the LCPH grating 1050. As shown in
In some embodiments, the controller 215 may control the LCPH grating 1050 to operate in the non-diffraction state by controlling the supplied voltage to be higher than the threshold voltage (and sufficiently high) to reorient the LC molecules LCPH grating 1050 to be parallel with the direction of the electric field. As shown in
As shown in
In some embodiments, at least one (e.g., each) of the two substrates 1106 may be provided with an alignment structure 1107. The alignment structure 1107 may provide a suitable alignment pattern to optically anisotropic molecules in the birefringent medium layer 1115. The alignment pattern may correspond to a predetermined in-plane orientation pattern, such as an in-plane orientation pattern with periodic linear orientations. The alignment structure 1107 may include a suitable alignment structure, such as a photo-alignment material (“PAM”) layer, a mechanically rubbed alignment layer, an alignment layer with anisotropic nanoimprint, an anisotropic relief, or a ferroelectric or ferromagnetic material layer, etc.
In some embodiments, at least one (e.g., each) of the two substrates 1106 may be provided with a transparent conductive electrode layer (e.g., ITO electrode) layer 1108. One or more power sources (not shown) may be electrically coupled with the LCPH element 1100. The one or more power sources may provide one or more electric fields to the LCPH element 1100 via the electrode layer 1108. In some embodiments, the LCPH element 1100 may include two electrode layers 1108, and a power source may provide an electric field to the LCPH element 1100 via the two electrode layers 1108. In some embodiments, the two electrode layers 1108 may be disposed at the two substrates 1106, respectively. In some embodiments, both of the two electrode layers 1108 may include planar continuous electrodes. In some embodiments, both of the two electrode layers 1108 may include patterned electrodes, e.g., slit electrodes. In some embodiments, one of the two electrode layers 1108 may include a planar continuous electrode, and the other one of the two electrode layers 1108 may include patterned electrodes, e.g., slit electrodes.
In some embodiments, each electrode layer 1108 may include two sub-electrode layers, and an electrically insulating layer disposed between the two sub-electrode layers. A respective power source may be electrically coupled with the two sub-electrode layers in each electrode layer 1108, thereby providing a respective electric field to the LCPH element 1100. In some embodiments, the two sub-electrode layers may include a planar continuous electrode and patterned electrodes.
The birefringent medium layer 1115 may have a first surface 1115-1 on one side and a second surface 1115-2 on an opposite side. The first surface 1115-1 and the second surface 1115-2 may be surfaces along the light propagating path of the incident light 1102. The birefringent medium layer 1115 may include optically anisotropic molecules (e.g., LC molecules) configured with a three-dimensional (“3D”) orientational pattern to provide a polarization selective optical response. In some embodiments, an optic axis of the LC material or birefringent medium layer 1115 may be configured with a spatially varying orientation in at least one in-plane direction. The in-plane direction may be an in-plane linear direction (e.g., an x-axis direction, a y-axis direction), an in-plane radial direction, an in-plane circumferential (e.g., azimuthal) direction, or a combination thereof. The LC molecules may be configured with an in-plane orientation pattern, in which the directors of the LC molecules may periodically or non-periodically vary in the at least one in-plane direction. In some embodiments, the optic axis of the LC material may also be configured with a spatially varying orientation in an out-of-plane direction. The directors of the LC molecules may also be configured with spatially varying orientations in an out-of-plane direction. For example, the optic axis of the LC material (or directors of the LC molecules) may twist in a helical fashion in the out-of-plane direction.
As shown in
For simplicity of illustration and discussion, the LCPH element 1100 shown in
In addition, in the film plane of the birefringent medium layer 1115, the orientations of the directors of the LC molecules 1112 may exhibit a rotation in a predetermined rotation direction, e.g., a clockwise direction or a counter-clockwise direction. Accordingly, the rotation exhibited in the orientations of the directors of the LC molecules 1112 in the film plane of the birefringent medium layer 1115 may exhibit a handedness, e.g., right handedness or left handedness. In the embodiment shown in
In the embodiment shown in
In the embodiment shown in
In the embodiment shown in
As shown in
As shown in
In the embodiment shown in
In the embodiment shown in
In the embodiment shown in
In some embodiments, the present disclosure provides a device that includes a light guide. The device also includes an in-coupling element coupled with the light guide and configured to couple a first image light into the light guide as a second image light propagating inside the light guide via total internal reflection (“TIR”), and to couple a portion of the second image light out of the light guide as a third image light. The device further includes a recycling element coupled with the light guide and configured to couple the third image light back into the light guide as a fourth image light propagating inside the light guide via TIR.
In some embodiments, the portion of the second image light that is coupled, via the in-coupling element, out of the light guide as the third image light is a first portion of the second image light. A second portion of the second image light propagates inside the light guide via TIR. In some embodiments, the fourth image light and the second portion of the second image light have a same TIR propagation angle inside the light guide. In some embodiments, the device further includes an out-coupling element coupled with the light guide, and configured to couple the fourth image light and the second portion of the second image light having the same TIR propagation angle out of the light guide to form a same image.
In some embodiments, the in-coupling element includes an in-coupling grating configured to diffract the portion of the second image light out of the light guide as the third image light. In some embodiments, the recycling element includes a recycling grating configured to diffract the third image light back into the light guide as the fourth image light. In some embodiments, the recycling element includes a recycling grating configured to diffract the third image light as a fifth image light toward an interface between the recycling grating and an outside environment, wherein the fifth image light is reflected at the interface as the fourth image light. In some embodiments, the recycling element and the in-coupling element are disposed at opposite surfaces of the light guide.
In some embodiments, the present disclosure provides a device that includes a light guide. The device also includes an in-coupling grating coupled with the light guide and configured to couple, via diffraction, a first image light having a first polarization into the light guide as a second image light propagating inside the light guide via total internal reflection (“TIR”). The device also includes a retardation film coupled with the light guide and configured to convert the second image light incident thereon as a third image light having a second polarization that is orthogonal to the first polarization. The in-coupling grating is configured to enable the third image light having the second polarization to propagate inside the light guide via TIR as a fourth image light. In some embodiments, the second image light and the fourth image light have a same TIR propagation angle inside the light guide. In some embodiments, the in-coupling grating includes a polarization volume hologram grating configured to diffract a circularly polarized light when the circularly polarized light has a first handedness, and transmit the circularly polarized light when the circularly polarized light has a second handedness that is orthogonal to the first handedness. In some embodiments, the in-coupling grating and the retardation film are disposed at opposite surfaces of the light guide. In some embodiments, the in-coupling grating is disposed between the retardation film and the light guide.
In some embodiments, the present disclosure provides a device including a light guide. The device also includes an in-coupling element coupled with the light guide and configured to couple a first image light into the light guide as a second image light. The device also includes an out-coupling element coupled with the light guide and including a plurality of out-coupling gratings configured to be selectively activated to couple the second image light out of the light guide. The device also includes at least one redirecting element coupled with the light guide. The device further includes a controller configured to control the in-coupling element to selectively direct the second image light to propagate in one of a plurality of selectable directions inside the light guide. The at least one redirecting element is configured to redirect the second image light when the second image light is received from the in-coupling element, to propagate toward a predetermined portion of the out-coupling element.
In some embodiments, the predetermined portion of the out-coupling element is a first portion of the out-coupling element. In some embodiments, the plurality of selectable directions include a first direction toward one of the at least one redirecting element, and a second direction directly toward a second portion of the out-coupling element. In some embodiments, the controller is configured to control the in-coupling element to direct the second image light to propagate in the first direction toward one of the at least one redirecting element, or in the second direction directly toward the second portion the out-coupling element. In some embodiments, the at least one redirecting element is configured to diffract the second image light propagating in the first direction as a third image light propagating toward the first portion of the out-coupling element via total internal reflection (“TIR”). In some embodiments, the third image light have a same TIR propagation angle inside the light guide as the second image light propagating in the second direction toward the second portion of the out-coupling element.
In some embodiments, the at least one redirecting element includes a plurality of redirecting elements coupled with the light guide at different positions, and the plurality of selectable directions include directions from the in-coupling element to the plurality of redirecting elements. In some embodiments, the controller is configured to control the in-coupling element to direct the second image light to propagate in a direction selected from the plurality of selectable directions toward one of the plurality of redirecting elements. In some embodiments, the one of the plurality of redirecting elements is configured to redirect the second image light to propagate toward the predetermined portion of the out-coupling element. In some embodiments, the plurality of redirecting elements are configured to redirect the second image light to propagate toward different predetermined portions of the out-coupling element. In some embodiments, the device further includes a retardation film coupled with the light guide and configured to convert a polarization of the second image light incident thereon. In some embodiments, the device further includes a recycling element coupled with the light guide and configured to recycle a portion of the second image light that is coupled out of the light guide by the in-coupling element.
In some embodiments, the present disclosure provides a device including a light guide. The device also includes an in-coupling grating coupled with the light guide and configured to couple, via diffraction, a first image light having a first polarization into the light guide as a second image light propagating inside the light guide via total internal reflection (“TIR”). The device also includes a retardation film coupled with the light guide and configured to convert the second image light incident thereon as a third image light having a predetermined polarization. The in-coupling grating is configured to reflect the third image light propagating through a volume of the in-coupling grating at a surface of the in-coupling grating as a fourth image light having a second polarization that is orthogonal to the first polarization. The volume of the in-coupling grating is configured to transmit the fourth image light having the second polarization as a fifth image light propagating inside the light guide via TIR.
The foregoing description of the embodiments of the present disclosure have been presented for the purpose of illustration. It is not intended to be exhaustive or to limit the disclosure to the precise forms disclosed. Persons skilled in the relevant art can appreciate that modifications and variations are possible in light of the above disclosure.
Some portions of this description may describe the embodiments of the present disclosure in terms of algorithms and symbolic representations of operations on information. These operations, while described functionally, computationally, or logically, may be implemented by computer programs or equivalent electrical circuits, microcode, or the like. Furthermore, it has also proven convenient at times, to refer to these arrangements of operations as modules, without loss of generality. The described operations and their associated modules may be embodied in software, firmware, hardware, or any combinations thereof.
Any of the steps, operations, or processes described herein may be performed or implemented with one or more hardware and/or software modules, alone or in combination with other devices. In one embodiment, a software module is implemented with a computer program product including a computer-readable medium containing computer program code, which can be executed by a computer processor for performing any or all of the steps, operations, or processes described. In some embodiments, a hardware module may include hardware components such as a device, a system, an optical element, a controller, an electrical circuit, a logic gate, etc.
Embodiments of the present disclosure may also relate to an apparatus for performing the operations herein. This apparatus may be specially constructed for the specific purposes, and/or it may include a general-purpose computing device selectively activated or reconfigured by a computer program stored in the computer. Such a computer program may be stored in a non-transitory, tangible computer readable storage medium, or any type of media suitable for storing electronic instructions, which may be coupled to a computer system bus. The non-transitory computer-readable storage medium can be any medium that can store program codes, for example, a magnetic disk, an optical disk, a read-only memory (“ROM”), or a random access memory (“RAM”), an Electrically Programmable read only memory (“EPROM”), an Electrically Erasable Programmable read only memory (“EEPROM”), a register, a hard disk, a solid-state disk drive, a smart media card (“SMC”), a secure digital card (“SD”), a flash card, etc. Furthermore, any computing systems described in the specification may include a single processor or may be architectures employing multiple processors for increased computing capability. The processor may be a central processing unit (“CPU”), a graphics processing unit (“GPU”), or any processing device configured to process data and/or performing computation based on data. The processor may include both software and hardware components. For example, the processor may include a hardware component, such as an application-specific integrated circuit (“ASIC”), a programmable logic device (“PLD”), or a combination thereof. The PLD may be a complex programmable logic device (“CPLD”), a field-programmable gate array (“FPGA”), etc.
Embodiments of the present disclosure may also relate to a product that is produced by a computing process described herein. Such a product may include information resulting from a computing process, where the information is stored on a non-transitory, tangible computer readable storage medium and may include any embodiment of a computer program product or other data combination described herein.
Further, when an embodiment illustrated in a drawing shows a single element, it is understood that the embodiment or an embodiment not shown in the figures but within the scope of the present disclosure may include a plurality of such elements. Likewise, when an embodiment illustrated in a drawing shows a plurality of such elements, it is understood that the embodiment or an embodiment not shown in the figures but within the scope of the present disclosure may include only one such element. The number of elements illustrated in the drawing is for illustration purposes only, and should not be construed as limiting the scope of the embodiment. Moreover, unless otherwise noted, the embodiments shown in the drawings are not mutually exclusive, and they may be combined in any suitable manner. For example, elements shown in one figure/embodiment but not shown in another figure/embodiment may nevertheless be included in the other figure/embodiment. In any optical device disclosed herein including one or more optical layers, films, plates, or elements, the numbers of the layers, films, plates, or elements shown in the figures are for illustrative purposes only. In other embodiments not shown in the figures, which are still within the scope of the present disclosure, the same or different layers, films, plates, or elements shown in the same or different figures/embodiments may be combined or repeated in various manners to form a stack.
Various embodiments have been described to illustrate the exemplary implementations. Based on the disclosed embodiments, a person having ordinary skills in the art may make various other changes, modifications, rearrangements, and substitutions without departing from the scope of the present disclosure. Thus, while the present disclosure has been described in detail with reference to the above embodiments, the present disclosure is not limited to the above described embodiments. The present disclosure may be embodied in other equivalent forms without departing from the scope of the present disclosure. The scope of the present disclosure is defined in the appended claims.
