Embodiments of the present disclosure generally relate to waveguide combiners. More specifically, embodiments described herein provide for single-sheet waveguide combiners having increased field-of-view for multiple colors.
Virtual reality is generally considered to be a computer generated simulated environment in which a user has an apparent physical presence. A virtual reality experience can be generated in 3D and viewed with a head-mounted display (HMD), such as glasses or other wearable display devices that have near-eye display panels as lenses that display a virtual reality environment that replaces an actual environment.
Augmented reality enables an experience in which a user can see through the display lenses of the glasses or other HMD device to view the surrounding environment while also seeing images of virtual objects that are generated for display and appear as part of the environment. Diffractive waveguide combiners are used in some augmented reality applications to transmit virtual images, graphics, and video that enhance or augment the environment that the user experiences.
In diffractive waveguide combiners, field-of-view (FOV) in one sheet of glass is limited by the ability to fit all colors and all angles into total internal reflection (TIR) within the substrate. There is a limited extent to which typical grating layouts can increase FOV without creating spurious paths that can cause ghost images to be presented to a user. Generally, the only ways to do so are to either increase the refractive index of the substrate (thus allowing more room in TIR), or to use multiple sheets of glass and not put all colors in one sheet. It is therefore desirable to develop single-sheet waveguide combiners having increased FOV for multiple colors.
In an embodiment, a waveguide is provided. The waveguide includes a first region, a second region, a third region, a fourth region, and a fifth region. The first region includes an in-coupler (IC) grating for a first color. The second region includes an IC grating for a second color and a third color. The third region includes an out-coupler (OC) grating for the first color and an eye-pupil-expander (EPE) grating for the second color and the third color. The fourth region includes an EPE grating for the first color. The fifth region includes an OC grating for the second color and the third color and an EPE grating for the first color. The fifth region at least partially overlaps with the third region.
In an embodiment, a waveguide is provided. The waveguide includes a first region, a second region, a third region, a fourth region, and a fifth region. The first region includes an in-coupler (IC) grating for a first color. The second region includes an IC grating for a second color and a third color. The third region includes an out-coupler (OC) grating for the first color and an eye-pupil-expander (EPE) grating for the second color and the third color. The fourth region includes an EPE grating for the second color and the third color. The fifth region includes an OC grating for the second color and the third color and an EPE grating for the first color. The fifth region at least partially overlaps with the third region.
In an embodiment, a waveguide is provided. The waveguide includes a first region, a second region, a third region, a fourth region, and a fifth region. The first region includes an in-coupler (IC) grating for a first color. The second region includes an IC grating for a second color. The third region includes an out-coupler (OC) grating for the first color and an eye-pupil-expander (EPE) grating for the second color and a third color. The fourth region includes an EPE grating for the first color. The fifth region includes an OC grating for the second color and the third color and an EPE grating for the first color. The fifth region at least partially overlaps with the third region.
So that the manner in which the above recited features of the present disclosure can be understood in detail, a more particular description of the disclosure, briefly summarized above, may be had by reference to embodiments, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only exemplary embodiments and are therefore not to be considered limiting of its scope, may admit to other equally effective embodiments.
To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common to the figures. It is contemplated that elements and features of one embodiment may be beneficially incorporated in other embodiments without further recitation.
The present disclosure relate to single-sheet waveguide combiners (also referred to herein as “waveguides”) having increased field-of-view for multiple colors by enabling separate action on different colors without creating spurious paths.
In diffractive waveguide combiners, field-of-view (FOV) in one sheet of glass is limited by the ability to fit all colors and all angles into total internal reflection (TIR) within the substrate. Increasing FOV with typical grating layouts can create spurious paths within the waveguide combiner that can cause ghost images to be presented to a user. Increasing the refractive index of the substrate (thus allowing more room in TIR) may not be practical, as higher refractive index materials may be too expensive for use in the waveguide combiners. Using multiple sheets of glass and putting some colors in each of the sheets increases the expense of manufacturing the waveguide combiners.
Aspects of the present disclosure provide a layout (e.g., an arrangement) of gratings that allows red light to use a different set of fundamental grating vectors from blue and green light without introducing ghost images within the displayed FOV. Aspects of the present disclosure provide another layout (e.g., an arrangement) of gratings that allows blue light to use a different set of fundamental grating vectors from red and green light without introducing ghost images within the displayed FOV.
The present disclosure may provide single-sheet waveguide combiners having increased FOV for multiple colors. The provided single-sheet waveguide combiners may have expanded FOV while being simpler and/or less expensive to manufacture than typical waveguide combiners.
Aspects of the present disclosure enable an FOV of a single-sheet waveguide to approach the possible FOV of a 2-sheet waveguide. In a 2-sheet waveguide, the FOV can be expanded because one of the sheets supports a combination of two colors, and the other sheet supports a third color. For example, a first sheet may support blue and green light (BG), and a second sheet may support red light (R). In another example, a first sheet may support a combination of green and red light (GR), and a second sheet may support blue light (B). Because the range of wavelengths inside each sheet of the waveguide is reduced, the number of angles that can be supported in total-internal-reflection (TIR) is increased.
In previously known single-sheet waveguides, creating a set of gratings that acts separately on different channels is impractical. In all such cases, all channels of light will interact with the same gratings, and so scaling the pitches of the gratings to account for dispersion (as is done in multi-sheet waveguides) leads to ghost images appearing and being seen by the user.
According to aspects of the present disclosure, advantages of multi-sheet gratings are enabled in a single sheet by specifically choosing grating vectors that do not produce ghost paths within the FOV when either channel interacts with them. In embodiments of the present disclosure, each non-in coupler (non-IC) grating has an associated function for both channels of light obtained from IC gratings (e.g., both of a B channel and a GR channel). The grating functions of the non-IC gratings cause a grating vector of each eye-pupil-expander (EPE) for a channel including a first set of colors (e.g., a set of red and green or a set of blue and green) to be either one-half of or double the grating vector of the out coupler (OC) for the channel including the color (e.g., blue or red) that is not in the first set of colors.
Side 230 includes an EPE for blue and green light (EPE(BG)) 232 and a combination out-coupler for red light and eye-pupil-expander for blue light and green light (OC(R)+EPE(BG)) 236. Some of the blue light and green light from the IC(BG) 202 (see
While
In the arrangement 260 of the two sides 200 and 230 shown in
In aspects of the present disclosure, the relationship between grating vectors k of the gratings in the arrangement 260 is represented in equation (1):
where kEPE(BG) is the grating vector of the EPE(BG) grating and kOC(R) is the grating vector of the OC(R) grating.
In aspects of the present disclosure, the arrangement 260 of the gratings shown in
Side 430 includes an EPE for blue light (EPE(B)) 432 and a combination out-coupler for green and red light and eye-pupil-expander for blue light (OC(GR)+EPE(B)) 436. Some of the blue light from the IC(B) 402 (see
While
In the arrangement 460 of the two sides 400 and 430 shown in
In aspects of the present disclosure, the relationship between grating vectors k of the gratings in the arrangement 460 is represented in equation (2):
where kEPE(B) is the grating vector of the EPE(B) grating and kOC(GR) is the grating vector of the OC(GR) grating.
In aspects of the present disclosure, the arrangement 460 of the gratings shown in
While the foregoing is directed to embodiments of the present disclosure, other and further embodiments of the disclosure may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.
This application claims priority to U.S. Provisional Patent Application No. 63/521,034, filed Jun. 14, 2023, the entirety of which is herein incorporated by reference.
Number | Date | Country | |
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63521034 | Jun 2023 | US |