KR20230173212A - Waveguide device with uniform output illumination - Google Patents

Abstract

Various embodiments of waveguide devices are described. Debanding optics can be integrated into the waveguide devices, which can help provide uniform output illumination. Accordingly, various waveguide devices can output a substantially flat illumination profile that eliminates or mitigates banding effects.

Description

Waveguide device with uniform output illumination {WAVEGUIDE DEVICE WITH UNIFORM OUTPUT ILLUMINATION}

The present invention relates to waveguide devices and, more particularly, to waveguides with uniform output illumination.

Waveguide optics are currently being considered for a variety of display and sensor applications where the ability of waveguide devices to integrate multiple optical functions into thin, transparent, lightweight substrates is critical. This new approach enables near-eye displays for augmented reality (AR) and virtual reality (VR), compact heads-up displays (HUDs) for aviation and road transport, and biometric and laser radar (LIDAR) applications. We are promoting the development of new products such as sensors for

Waveguide devices offer several attractive features in HMDs and HUDs. These are thin and transparent. Extensive fields of view can be obtained by recording multiple holograms and tiling the viewing area formed by each hologram.

Some embodiments include at least one optical substrate, at least one light source, at least one optical coupler, at least one light extractor, and debanding optic. The at least one optical coupler couples incident light from a light source with an angular bandwidth to total internal reflection (TIR) within the at least one optical substrate such that a unique TIR angle is determined from the input grating. It can be defined by the same angle of incidence of each light. At least one light extractor extracts light from the optical substrate. Debanding optics can alleviate the banding effects of the illuminated pupil, such that the extracted light has a substantially flat illumination profile with relaxed banding.

In many embodiments, the extracted light has a spatial non-uniformity of less than 10%.

In other embodiments, the extracted light has a spatial non-uniformity of less than 20%.

In still other embodiments, the debending optic is an effective input aperture such that the input aperture is configured to provide a TIR angle (U) to the optical substrate when the optical substrate has a thickness (D). And the angle (U) is calculated as 2D tan(U).

In further embodiments, the debanding optics provide spatial variation of light along the TIR path in at least one of diffraction efficiency, optical transmission, polarization, or birefringence.

In another embodiment, the debanding optics are at least one grating selected from at least one input grating and at least one output grating. At least one selected grating is configured to have multiple gratings, each grating providing a small pupil shift to mitigate banding.

In many other embodiments, the debanding optical device is at least one grating selected from at least one input grating and at least one output grating. The at least one selected grating is configured as a stacked switchable grating that turns on when a voltage is applied, shifting the pupil to mitigate banding effects.

In many other embodiments, the debanding optical device is at least one grating selected from at least one input grating and at least one output grating. The at least one selected grating is configured as an array of switchable grating elements that can turn on specific elements when a voltage is applied, shifting the pupil to mitigate banding effects.

In many other embodiments, at least one grid selected has a plurality of rolled K-vectors.

In many other embodiments, the debanding optical device is at least one grating selected from at least one input grating and at least one output grating. The at least one grating selected is configured to be a plurality of passive grating layers configured to shift the pupil to mitigate banding effects.

In many other embodiments, the debending optical device comprises one or more index layers disposed within an optical substrate, wherein the one or more index layers modulate light ray paths within the optical substrate as a function of at least one of ray angle or ray position. and shifts the pupil to alleviate the banding effect.

In many other embodiments, at least one of the one or more index layers is a gradient index (GRIN) medium.

In many other embodiments, the waveguide device further includes at least one reflective surface on at least a portion of an edge of the optical substrate. A debending optical device is one or more index layers disposed adjacent to at least one reflective surface, wherein the one or more index layers are configured to shift the pupil to mitigate banding effects.

In yet many other embodiments, a debending optical device comprises one or more index layers disposed within an optical substrate, wherein the one or more index layers are configured to shift the pupil to mitigate banding effects.

In many other embodiments, the debanding optical device is an input grating having a leading edge capable of combining incident light, and determining an inherent displacement of a ray bundle of light relative to the leading edge of the input grating. A unique displacement is provided by the input grating for any given incident light direction and shifts the pupil to mitigate banding effects.

In yet many other embodiments, the debanding optical device is an input grating configured to have a change in diffraction efficiency, wherein a plurality of collimated incident light paths of incident light are diffracted into different TIR light paths as determined by the light path input angle. And, the projected pupil can be formed at a unique position within the optical substrate for each of the plurality of collimated incident light paths, thereby mitigating the banding effect.

In many other embodiments, the change in diffraction efficiency varies along the main waveguide direction.

In many other embodiments, the change in diffraction efficiency varies in two dimensions across the aperture of the input grating.

In many other embodiments, the debending optical device is a partially reflective layer disposed within an optical substrate, wherein the partially reflective layer separates incident light into transmitted and reflected light and shifts the pupil to alleviate the banding effect. I order it.

In many other embodiments, a debending optical device is a polarization modifying layer disposed within an optical substrate, where the polarization modifying layer separates incident light into transmitted and reflected light and shifts the pupil to produce a bending effect. alleviates

In many other embodiments, the debanding optical device is at least one grating selected from at least one input grating and at least one output grating. The at least one grating selected is configured to provide at least two separate waveguide paths that eliminate non-uniformity in the extracted light for any incident light angle, thereby mitigating banding effects.

In many other embodiments, the selected grating has crossed slant gratings used in conjunction with at least one fold grating exit pupil expander.

In yet many other embodiments, debanding optics include microscopic devices that provide variable effective numerical apertures (NA) that can be spatially varied along at least one direction to shift the pupil to mitigate banding effects. It is an optical component within the display.

In yet many other embodiments, the debanding optical device comprises a plurality of grating layers within at least one of at least one input grating or at least one output grating, wherein the plurality of grating layers smear any fixed pattern noise. Smear out and shift the pupil to alleviate the banding effect.

In many other embodiments, the debanding optical device is an input grating configured as an array of selectively switchable elements, wherein configuring the input grating as a switching grating array provides pupil switching in vertical and horizontal directions to effect banding. Shift the pupil to alleviate.

In yet many other embodiments, debanding optics provide spatial variations along each TIR path in at least one of diffraction efficiency, light transmission, polarization, and birefringence as a function of at least one of light beam angle or light position within the substrate, A plurality of refractive index layers that influence the light ray paths within the waveguide substrate and shift the pupil to alleviate the banding effect.

In yet many other embodiments, the plurality of refractive index layers include adhesives of different indices.

In many other embodiments, the plurality of refractive index layers comprise layers selected from the group consisting of alignment layers, isotropic refractive layers, GRIN structures, anti-reflective layers, partially reflective layers, and birefringent stretched polymer layers. .

In yet many other embodiments, the debending optical device is a micro-display that projects a spatially varied numerical aperture that shifts the pupil to mitigate banding effects.

In many other embodiments, the debending optical device is an inclined micro-display configured to project an inclined rectangular exit pupil such that the cross-section of the exit pupil varies with field angle to mitigate banding effects.

In many other embodiments, the debending optical device is a tilting micro-display configured to tilt a light beam to form various projected pupils at different locations along the optical substrate for each angle of incident light, wherein the bending effect is one It relaxes along the expansion axis.

In many other embodiments, the optical substrate has a thickness D, and the debending optical device is a prism coupled to the optical substrate, wherein the linear relationship between the angles of the exit pupil from the light source and the TIR angles in the optical substrate is TIR. It does not create a gap between successive light extractions along the TIR ray path, which occurs when the path angle is U as defined by 2D tan(U).

In yet many other embodiments, the debending optical device is a light-absorbing film adjacent the edges of the optical substrate such that portions of incident light that would otherwise cause bending are removed, thus mitigating the banding effect.

In many other embodiments, the optical substrate has a thickness D, and the debending optical device includes an input grating and a first light-absorbing film disposed adjacent edges of the input substrate disposed adjacent the optical substrate. A second light-absorbing film disposed adjacent the edges of a second substrate disposed adjacent the optical substrate opposite the input substrate, wherein the incident light has a TIR path angle U as defined by 2D tan(U). It does not create gaps between successive light extractions along the resulting TIR light path.

In many other embodiments, the optical substrate is 3.4 mm thick, the second substrate is 0.5 mm thick, and the input substrate includes two 0.5 mm thick glass substrates sandwiching the input grating.

In many other embodiments, a debending optical device is an input grating configured to shift the pupil such that the light has an inherent displacement relative to an edge of the input grating in any given incident light direction, thereby eliminating or mitigating banding effects. .

In yet many other embodiments, the device is integrated into a display selected from the group of head-mounted displays (HMDs) and head-up displays (HUDs).

In many other embodiments, the human eye is positioned with the exit pupil of the display.

In yet many other embodiments, the device includes an eye tracker.

In many other embodiments, the waveguide device further includes a light source, a micro display panel, and an input image generator further including optical devices for collimating the light.

In yet many other embodiments, the light source is at least one laser.

In many other embodiments, the light source is at least one light emitting diode (LED).

In yet many other embodiments, the optical coupler is an input grating.

In yet many other embodiments, the optical coupler is a prism.

In many other embodiments, the light extractor is an input grating.

Some embodiments relate to a color waveguide device including at least two optical substrates, at least one light source, at least one optical coupler, at least one light extractor, and at least two input stops. The at least two optical substrates are stacked on each other. The at least one optical coupler couples incident light from a light source with an angular bandwidth to total internal reflection (TIR) within the at least one optical substrate, such that a unique TIR angle is determined from the input grating. Likewise, it can be defined by each light incident angle. At least one light extractor extracts light from the optical substrate. The at least two input stops are each in a different optical substrate, each in a different plane, and each input stop includes an outer dichroic portion that shifts the pupil and alleviates color banding.

In many embodiments, each input stop also includes an inner phase compensation coating to compensate for phase shift.

In other embodiments, the compensatory coating includes SiO ₂ .

Some embodiments relate to a method of mitigating banding in the output illumination of a waveguide device. The method produces incident light from a light source. The method couples the incident light to an optical substrate by passing the incident light through an optical coupler, thereby causing the coupled light to undergo total internal reflection (TIR) within the optical substrate. The method also generates output illumination by extracting TIR light from the optical substrate through a light extractor. The light passes through the debanding optic of the waveguide device, which mitigates the banding effect of the output light.

In many embodiments, the output illumination has a spatial non-uniformity of less than 10%.

In other embodiments, the output illumination has a spatial non-uniformity of less than 20%.

In still other embodiments, the debending optic is an effective input aperture, such that the input aperture is configured to provide a TIR angle (U) to the optical substrate when the optical substrate has a thickness (D), wherein the angle ( U) is calculated as 2D tan(U).

In further embodiments, the debanding optical device provides spatial variation of light along the TIR path in at least one of diffraction efficiency, light transmission, polarization, or birefringence.

In still other embodiments, the debanding optic is at least one grating selected from at least one input grating and at least one output grating. At least one grating selected is configured to have multiple gratings, each grating providing a small pupil shift to mitigate banding.

In many other embodiments, the debanding optical device is at least one grating selected from at least one input grating and at least one output grating. The at least one selected grating is configured as a stacked switchable grating that turns on when a voltage is applied, shifting the pupil to mitigate banding effects.

In many other embodiments, the debanding optical device is at least one grating selected from at least one input grating and at least one output grating. The at least one selected grating is configured as an array of switchable grating elements that can turn on specific elements when a voltage is applied, shifting the pupil to mitigate banding effects.

In many other embodiments, at least one grid selected has a plurality of rolled K-vectors.

In many other embodiments, the debanding optical device is at least one grating selected from at least one input grating and at least one output grating. The at least one grating selected is configured to be a plurality of passive grating layers configured to shift the pupil to mitigate banding effects.

In many other embodiments, a debending optical device comprises one or more index layers disposed within an optical substrate, wherein the one or more index layers influence light ray paths within the optical substrate as a function of at least one of ray angle or ray position. and shift the pupil to alleviate the banding effect.

In many other embodiments, at least one of the one or more index layers is a gradient refractive index (GRIN) medium.

In many other embodiments, the waveguide device further includes at least one reflective surface on at least a portion of an edge of the optical substrate. A debending optical device is one or more index layers disposed adjacent to at least one reflective surface, wherein the one or more index layers are configured to shift the pupil to mitigate banding effects.

In yet many other embodiments, a debending optical device comprises one or more index layers disposed within an optical substrate, wherein the one or more index layers are configured to shift the pupil to mitigate banding effects.

In yet many other embodiments, a debanding optical device is an input grating having a leading edge capable of combining incident light, such that the inherent displacement of a bundle of light rays with respect to the leading edge of the input grating is equivalent to an input grating for any given incident light direction. is provided by, and shifts the pupil to alleviate the banding effect.

In many other embodiments, the debanding optic device is an input grating configured to have a change in diffraction efficiency, wherein a plurality of collimated incident light paths of incident light are diffracted into different TIR light paths as determined by the light path input angle. And, the projected pupil can be formed at a unique position within the optical substrate for each of the plurality of collimated incident ray paths to alleviate the banding effect.

In many other embodiments, the change in diffraction efficiency varies along the main waveguide direction.

In many other embodiments, the change in diffraction efficiency varies in two dimensions across the aperture of the input grating.

In many other embodiments, the debending optical device is a partially reflective layer disposed within an optical substrate, wherein the partially reflective layer separates incident light into transmitted and reflected light and shifts the pupil to alleviate the banding effect. I order it.

In many other embodiments, the debending optical device includes a polarization change layer disposed within an optical substrate, where the polarization change layer separates incident light into transmitted and reflected light and shifts the pupil to mitigate the banding effect.

In many other embodiments, the debanding optical device is at least one grating selected from at least one input grating and at least one output grating, wherein the selected at least one grating removes non-uniformity in the extracted light for any incident light angle. It is configured to provide at least two separate waveguide paths, thereby mitigating banding effects.

In yet many other embodiments, the selected grating has cross-slanted gratings used in conjunction with at least one folded grating exit pupil dilator.

In yet many other embodiments, the debanding optics include an optical component within the microdisplay that provides a variable effective numerical aperture (NA) that can be spatially varied along at least one direction to shift the pupil to mitigate banding effects. am.

In yet many other embodiments, the debanding optical device comprises a plurality of grating layers within at least one of at least one input grating or at least one output grating, wherein the plurality of grating layers smear any fixed pattern noise. Out and shift the pupil to alleviate the banding effect.

In many other embodiments, the debanding optical device is an input grating configured as an array of selectively switchable elements, wherein configuring the input grating as a switching grating array provides pupil switching in vertical and horizontal directions to effect banding. Shift the pupil to alleviate.

In many other embodiments, the debanding optics provide spatial variations along each TIR path in at least one of diffraction efficiency, light transmission, polarization, and birefringence to form a waveguide as a function of at least one of light beam angle or light position within the substrate. Multiple refractive index layers that affect the light ray paths within the substrate and shift the pupil to alleviate the banding effect.

In yet many other embodiments, the plurality of refractive index layers include adhesives of different indices.

In many other embodiments, the plurality of refractive index layers includes layers selected from the group consisting of alignment layers, isotropic refractive layers, GRIN structures, anti-reflective layers, partially reflective layers, and birefringent stretched polymer layers. .

In yet many other embodiments, the debending optical device is a micro-display that projects a spatially varied numerical aperture that shifts the pupil to mitigate banding effects.

In many other embodiments, the debending optical device is an inclined micro-display configured to project an inclined rectangular exit pupil such that the cross-section of the exit pupil varies with field angle to mitigate banding effects.

In many other embodiments, the debending optical device is a tilting micro-display configured to tilt a light beam to form various projected pupils at different locations along the optical substrate for each angle of incident light, wherein the bending effect is one It relaxes along the expansion axis.

In many other embodiments, the optical substrate has a thickness D, and the debending optical device is a prism coupled to the optical substrate, wherein the linear relationship between the angles of the exit pupil from the light source and the TIR angles in the optical substrate is TIR. It does not create a gap between successive light extractions along the TIR ray path, which occurs when the path angle is U as defined by 2D tan(U).

In yet many other embodiments, the debending optical device is a light-absorbing film adjacent the edges of the optical substrate such that portions of incident light that would otherwise cause bending are removed, thus mitigating the banding effect.

In many other embodiments, the optical substrate has a thickness D, and the debending optical device includes an input grating and a first light-absorbing film disposed adjacent edges of the input substrate disposed adjacent the optical substrate, and a second light-absorbing film disposed adjacent the edges of a second substrate disposed adjacent the optical substrate opposite the input substrate, wherein the incident light has a TIR path angle U as defined by 2D tan(U). It does not create gaps between successive light extractions along the TIR light path, as occurs when

In many other embodiments, the optical substrate is 3.4 mm thick, the second substrate is 0.5 mm thick, and the input substrate includes two 0.5 mm thick glass substrates sandwiching the input grating.

In yet many other embodiments, debending optics are input gratings configured such that light has a unique displacement relative to the edges of the input grating in any given incident light direction to shift the pupil, thereby eliminating or mitigating banding effects.

In yet many other embodiments, the method is implemented by a display selected from the group of head-mounted displays (HMDs) and head-up displays (HUDs).

In many other embodiments, the human eye is positioned with the exit pupil of the display.

In many other embodiments, the display includes an eye tracker.

In many other embodiments, the waveguide device further includes a light source, a micro display panel, and an input image generator further including optics for collimating the light.

In yet many other embodiments, the light source is at least one laser.

In many other embodiments, the light source is at least one light emitting diode (LED).

In yet many other embodiments, the optical coupler is an input grating.

In yet many other embodiments, the optical coupler is a prism.

In many other embodiments, the light extractor is an input grating.

Integrated Reference Materials

The following related patents and patent applications are incorporated herein by reference in their entirety: U.S. Patent No. 9,075,184, entitled Compact Edge-Lighted Diffractive Display; U.S. Patent No. 8,233,204, entitled Optical Display; PCT Application No. US2006/043938, entitled Method and Apparatus for Providing Transparent Display; PCT Application No. GB2012/000677, entitled Wearable Data Display; U.S. Patent Application No. 13/317,468, entitled Compact Edge-illuminated Eyeglass Display; U.S. Patent Application No. 13/869,866, entitled Holographic Wide Angle Display; U.S. Patent Application No. 13/844,456, entitled Transparent Waveguide Display; U.S. Patent Application No. 14/620,969, entitled Waveguide Grating Device; U.S. Provisional Patent Application No. 62/176,572, entitled Transparent Waveguide Display; U.S. Provisional Patent Application No. 62/177,494, entitled Waveguide Device Including Light Pipe; U.S. Provisional Patent Application No. 62/071,277, entitled Method and Apparatus for Generating Input Images for Holographic Waveguide Displays; U.S. Provisional Patent Application No. 62/123,282, entitled Near Eye Display Using Gradient Index Optics; U.S. Provisional Patent Application No. 62/124,550, entitled Waveguide Display Using Gradient Index Optics; U.S. Provisional Patent Application No. 62/125,064, entitled Optical Waveguide Display for Integration in Windows; U.S. Provisional Patent Application No. 62/125,066, entitled Optical Waveguide Display for Integration in Windows; U.S. Provisional Patent Application No. 62/125,089, entitled Holographic Waveguide Optical Field Display; U.S. Patent No. 8,224,133, entitled Laser Illumination Apparatus; U.S. Patent No. 8,565,560, entitled Laser Illumination Apparatus; U.S. Patent No. 6,115,152, entitled Holographic Lighting System; PCT Application No. PCT/GB2013/000005 entitled Contact Image Sensor Using Switchable Brush Grating; PCT Application No. PCT/GB2012/000680, entitled Improvements to Holographic Polymer Dispersed Liquid Crystal Materials and Devices; PCT Application No. PCT/GB2014/000197, entitled Holographic Waveguide Eye Tracker; PCT/GB2013/000210 entitled Device for eye tracking; PCT Application No. GB2013/000210, entitled Device for Eye Tracking; PCT/GB2015/000274 entitled Holographic Waveguide Optical Tracker; U.S. Patent No. 8,903,207, entitled Systems and Methods for Extending the Vertical Field of a Head-Up Display Using a Waveguide Complex; U.S. Patent No. 8,639,072, entitled Compact Wearable Display; U.S. Patent No. 8,885,112, entitled Compact Holographic Edge-Illuminated Eye Glass Display; U.S. Provisional Patent Application No. 62/390,271, entitled Holographic Waveguide Device for Use with Unpolarized Light; U.S. Provisional Patent Application No. 62/391,333, entitled Method and Apparatus for Providing Polarization Selective Holographic Waveguide Devices; U.S. Provisional Patent Application No. 62/493,578, entitled Waveguide Display Device; U.S. Provisional Patent Application No. 62/497,781, entitled Apparatus for Homogenizing Output from a Waveguide Device; PCT Application No. PCT/GB2016000181 entitled Waveguide Display; PCT/GB2016/00005 entitled Environmental Isolated Waveguide Display.

This specification will be more completely understood with reference to the following drawings, which are presented as exemplary embodiments of the invention and should not be construed as completely describing the scope of the invention.
Figure 1A provides a schematic cross-sectional view of a waveguide showing bending in one embodiment.
Figure 1B provides a chart showing the integration of light extracted from a waveguide to provide debanded illumination in one embodiment.
Figure 2 provides a schematic top view of the details of the waveguide illustrating the geometrical optical conditions for debending that may occur in one embodiment.
Figure 3 provides a chart showing the spatial variation of the optical properties of an optical layer used to provide a pupil shift means in one embodiment.
Figure 4 provides a schematic cross-sectional view of a waveguide using a switchable input grating in one embodiment.
Figure 5 provides a schematic cross-sectional view of a waveguide using a switchable output grating in one embodiment.
Figure 6A provides a schematic cross-sectional view of a waveguide using a switchable input grating in one embodiment.
Figure 6b provides details of a switchable grating showing rolled K-vectors in one embodiment.
Figure 7 provides a schematic top view of a switchable input grid in one embodiment.
Figure 8 provides a schematic cross-sectional view of details of a waveguide in which the debending optics are an optical beam modifying layer disposed on a reflective surface of the waveguide substrate.
Figure 9 provides a schematic cross-sectional view of details of a waveguide in which the debending optics are an optical beam modifying layer disposed within the waveguide substrate.
Figure 10 provides a schematic cross-sectional view of details of a waveguide in one embodiment where the debending optics is an input grating and varies the separation of the input beam from the leading edge of the input grating as a function of the angle of incidence of the beam.
Figure 11 provides a schematic cross-sectional view of details of a waveguide in one embodiment where the debending optics provide a projected pupil within the waveguide at positions dependent on the beam angle of incidence.
Figure 12 provides a schematic cross-sectional view of details of a waveguide in one embodiment where the debending optics are partially reflective layers.
Figure 13 provides a schematic cross-sectional view of details of a waveguide in one embodiment where the debending optics are a polarization rotating layer.
Figure 14 provides a schematic top view of a waveguide where, in one embodiment, the debending optics are a grating that provides separate optical paths through the waveguide for different polarizations of input light.
Figure 15 provides a schematic cross-sectional view of details of a micro display in one embodiment where the debending optics provide a variable numerical aperture across the major directions of the micro display panel.
Figure 16A provides a schematic cross-sectional view of a waveguide using stacked switching input gratings in one embodiment.
FIG. 16B provides a schematic cross-sectional view of details of a waveguide in one embodiment where the debending optics are a switchable input grating array.
FIG. 16C provides a schematic cross-sectional view of details of a waveguide, in one embodiment the debending optics being an optical beam modifying layer disposed within the waveguide substrate.
FIG. 16D provides a schematic cross-sectional view of details of a waveguide, in one embodiment a micro-display panel where the debending optics provide a variable numerical aperture across the principal directions.
Figure 16E provides a schematic cross-sectional view of details of a waveguide in one embodiment where the debending optics are oblique input image generators providing the exit pupil.
FIG. 16F provides a schematic cross-sectional view of details of a waveguide in one embodiment where the debending optics are an exit pupil and a gradient input image generator providing various projected pupils.
Figure 16G provides a schematic cross-sectional view of details of a waveguide in one embodiment where the debending optics are a gradient input image generator and a coupling prism.
Figure 16H provides a schematic cross-sectional view of details of a waveguide in one embodiment where the debending optics are a plurality of additional substrates with light absorbing edges.
Figure 17 provides a schematic cross-sectional view of details of a waveguide where in one embodiment the debending optics are a plurality of additional substrates with light absorbing edges.
Figure 18 provides a schematic cross-sectional view of details of a waveguide in one embodiment where the debending optics are a gradient input image generator and a coupling prism.
Figure 19 provides a schematic cross-section of a coating structure for use in balancing color registration in a color display in one embodiment.
Figure 20 provides a schematic cross-sectional view of details of a waveguide, the input grating of which debending optics offset the input beam cross-section from its edges.

Referring to the drawings, systems and methods related to near-eye display or head up display systems are shown, according to various embodiments. A number of embodiments relate to waveguide devices for use in near-eye displays or head-up display systems. A common problem present in many waveguide devices is banding in the output illumination, which affects its uniformity. Accordingly, various embodiments of waveguide devices with uniform output illumination are provided. In various embodiments of waveguide devices, debanding optics are included to eliminate or mitigate banding effects.

Many embodiments also relate to holographic waveguide technology that may be advantageously used in waveguide devices. In some embodiments, holographic waveguide technology is used in helmet-mounted displays or head-mounted displays (HMD) and head-up displays (HUD). In some embodiments, holographic waveguide technology is used in many applications, including avionics applications and consumer applications (eg, augmented reality glasses, etc.). In many embodiments, the eye is located within the exit pupil or eye box of the display.

In many embodiments, waveguide devices provide pupil expansion in two orthogonal directions using a single waveguide layer. Uniformity of output is achieved according to various embodiments by designing the output grating to have a diffraction efficiency that varies from a low value near the input end of the waveguide substrate to a high value at the furthest extremity of the output grating. do. In many embodiments, input image data is provided by a micro display external to the waveguide optical substrate and coupled to the substrate by an input grating. According to many embodiments the micro display is a reflective array and illuminated through a beamsplitter. The reflected image light is collimated so that each pixel in the image provides a parallel beam in its own direction.

According to a number of embodiments, a waveguide device efficiently couples image content to a waveguide in such a way that the waveguide image is free from chromatic dispersion and brightness non-uniformity. One way to prevent chromatic dispersion and achieve better collimation is to use lasers. However, the use of lasers is subject to pupil banding artifacts, which manifest themselves in the output illumination and disrupt the uniformity of the image. Banding artifacts can form when the collimated pupil is replicated (dilated) in a total internal reflection (TIR) waveguide. Banding occurs when some of the light beams diffracted from the waveguide exhibit a gap or overlap whenever the beam interacts with the grating, leading to an illumination ripple. The degree of ripple is a function of field angle, waveguide thickness, and aperture thickness. As depicted in the various embodiments described herein, experiments and simulations have shown that the banding effect can be smoothed by dispersion with broadband sources such as light emitting diodes (LEDs). However, LED lighting is not completely free from the banding problem, especially for higher waveguide thicknesses relative to the waveguide input-aperture ratios. Additionally, LED lighting tends to result in bulky input optics and an increase in the thickness of the waveguide device. Accordingly, many embodiments of the waveguide device described herein have compact and efficient debanding optics to homogenize the light output from the holography to prevent banding distortion.

Banding effects cause non-uniformity in output lighting. As discovered in several prototype tests, actual illumination from a waveguide device should achieve a non-uniformity of less than 20%, preferably less than 10%, to provide a satisfactory visible image. Achieving low nonuniformity requires compromises with other system requirements, especially image brightness. The trade-offs are difficult to define in precise terms and are highly application dependent. Because many optical techniques for reducing non-uniformity typically result in some light loss, output image brightness may be reduced. As the sensitivity of the human visual system to unevenness increases with light level, the problem of unevenness becomes a problem for displays such as automotive HUDs that require high luminous flux to achieve high display relative to background scene contrast. becomes more important. Accordingly, in some embodiments, the extracted light has a spatial non-uniformity of less than 10%. In many embodiments, the extracted light has a spatial non-uniformity of less than 20%.

Some embodiments of the invention will now be further described with reference to the accompanying drawings. For the purpose of describing various embodiments of the present invention, well-known features of optical techniques known to those skilled in the art of optical design and visual displays may be omitted or simplified so as not to obscure the basic principles of the various embodiments. Descriptions of various embodiments will be presented using terminology commonly used by those skilled in the art of optical design. Unless otherwise stated, the term "on-axis" with respect to a light ray or beam direction refers to propagation parallel to an axis perpendicular to the surfaces of the optical components described in connection with the various devices. refers to In the following description, the terms light, ray, beam and direction may be used interchangeably and in conjunction with each other to indicate the direction of propagation of electromagnetic radiation along straight trajectories. . The terms light and illumination may be used in relation to the visible and infrared bands of the electromagnetic spectrum. As used herein, the term grating encompasses, in some embodiments, a grid comprised of a set of gratings.

waveguide device

According to many embodiments, a waveguide device includes at least one optical substrate, at least one light source, at least one optical coupler to couple light from the light source to the optical substrate, and to couple light from the optical substrate to form output illumination. It includes at least one light extractor for extracting. 1A shows one embodiment of a waveguide device. Accordingly, waveguide device 100 includes at least one optical substrate 101, at least one input grating 102, and at least one output grating 103. Input grating 102, having a maximum aperture (W), couples light from light source 104 (ray arrays 1000-1002) into a total internal reflection (TIR) path 1004 within waveguide substrate 101. I order it. The input 102 and output 103 grids as shown in FIG. 1A may be in any suitable configuration, such as the grid configurations described herein.

In many embodiments, the waveguide device includes a light source, a micro display panel, and an input image generator further comprising an input image generator having optics for collimating the light. In the description of some embodiments, the input generator is referred to as a picture generation unit (PGU). In some embodiments, the source may be configured to provide general illumination that is not modulated with image information. In many embodiments, the input image generator projects the displayed image onto the micro-display panel such that each display pixel is translated into a unique angular orientation within the substrate waveguide. In various embodiments, collimating optics include at least lenses and mirrors. In many embodiments, the lenses and mirrors are diffractive. In some embodiments, the light source is at least one laser. In many embodiments, the light source is at least one LED. In many embodiments, various combinations of different light sources are used within the input image generator.

It should be understood that multiple input image generators may be used in accordance with various embodiments of the present invention. For example, US Patent Application Serial No. 13/869,866, entitled Holographic Wide Angle Display, and US Patent Application Serial No. 13/844,456, entitled Transparent Waveguide Display. In many embodiments, the input image generator includes a beamsplitter to direct light onto the micro display and transmit reflected light toward the waveguide. In some embodiments, the beamsplitter is a grating recorded on holographic polymer dispersed liquid crystal (HPDLC). In various embodiments, the beam splitter is a polarizing beam splitter cube. In some embodiments, the input image generator includes a despeckler. Any suitable despeckler may be used in various embodiments, such as, for example, those described in US Patent No. US8,565,560 entitled Laser Illumination Device.

In many embodiments, the light source further includes one or more lenses for modifying the angular characteristics of the illumination beam. In many embodiments, the image source is a micro display or laser-based display. Some embodiments of light sources utilize LEDs, which can provide better uniformity than lasers. When laser illumination is used, the risk of light banding effects is higher, but can still be eliminated or mitigated according to the various embodiments described herein. In certain embodiments, the light from the light source is polarized. In many embodiments, the image source is a liquid crystal display (LCD) microdisplay or a liquid crystal on silicon (LCoS) microdisplay.

In some embodiments, the input image generator optics include a polarizing beam splitter cube. In many embodiments, the input image generator optics include an inclined plate with a beam splitter coating applied thereto. In many embodiments, the input image generator optics include a switchable Bragg grating (SBG) that acts as a polarization selective beam splitter. Examples of input image generator optics including SBGs are disclosed in US Patent Application Serial No. 13/869,866, entitled Holographic Wide Angle Display, and US Patent Application Serial No. 13/844,456, entitled Transparent Wave Display. In many embodiments, the input image generator optics include at least one of a refractive component and a curved reflective surface or a diffractive optical element to control the numerical aperture of the illumination light. In many embodiments, the input image generator includes spectral filters to control the wavelength characteristics of the illumination light. In some embodiments, input image generator optics include an aperture, mask, filter, and coating to control stray light. In some embodiments, the micro display includes birdbath optics.

Returning to the embodiment shown in FIG. 1A , external source 102 provides collimated light rays to each bandwidth 1002 . Light in the TIR path 1004 interacts with the output grating 103 to extract a portion of the TIR light whenever it satisfies the conditions for diffraction by the grating. In the case of a Bragg grating, extraction occurs when the Bragg condition is met. For example, optical TIR ray path 1004 corresponding to TIR angle U is diffracted by the output grating in output direction 1005A. It is clear from basic geometrical optics that the unique TIR angle is defined by the angle of incidence of each light at the input grating. Light is extracted, forming three extraction beams, as shown, each of which is flanked by two rays 1005B and 1005C; 1006A and 1006B; 1007A and 1007B, respectively. Perfectly collimated gaps (1006C and 1007C shown as crosshatching) will break out between adjacent beam extracts, causing a banding effect. According to many embodiments, beam gaps that cause bending are eliminated or minimized by a plurality of debending optics as described herein. For example, debending optics configure the light such that the input grating has an effective input aperture (W') that depends on the TIR angle (U).

In many embodiments, the waveguide device includes debending optics that can shift the pupil to configure light coupled to the waveguide such that the input grating has an effective input aperture that is a function of the TIR angle. The effect of debending optics is that the successive light extractions from the waveguide by the output grating are integrated to provide a substantially flat illumination profile for any angle of light incidence at the input grating. In some embodiments, the debending optical device includes various types of optical beams including, but not limited to, gratings, partially reflective films, liquid crystal alignment layers, isotropic refractive layers, and gradient index (GRIN) structures. It is implemented by combining change layers. It should be understood that the term “beam-modifying” refers to changes in amplitude, polarization, phase, and wavefront displacement in three-dimensional space as a function of incident light angle. In each case, the beam-modifying layers according to some embodiments provide an effective aperture that provides uniform extraction across the output grating for any angle of light incidence at the input grating. In many embodiments, beam-modifying layers are used with a means of controlling the numerical aperture of input light as a function of input angle. In some embodiments, beam-modifying layers are used in conjunction with technology to provide wavelength diversity.

Figure 1B provides a chart showing the effect of pupil shifting optics on the light output from the waveguide (denoted I) along the main propagation direction indicated Z (with reference to the coordinate system shown in Figure 1A). Intensity profiles 1008A-1008C are shown for three consecutive extracts corresponding to the input light direction. The shape of the intensity profile is controlled by the prescription of the beam-modifying layers. In many embodiments, the intensity profiles are integrated to provide a substantially flat intensity profile. For example, intensity profiles 1008A-1008C are integrated into flat profile 1009.

Input couplers and extractors used in waveguide devices

Waveguide devices are currently of interest in a variety of display and sensor applications. Although much of the previous work on devices concerned reflective holograms, transmission devices have proven to be much more versatile as optical system building blocks. Accordingly, a number of embodiments relate to the use of gratings in waveguide devices that can be used for input or output of a pupil. In many embodiments, the input grating is a type of optical input coupler that couples light from the source to the waveguide. In many embodiments, the output grating is a type of light extractor for extracting light from the waveguide to form output illumination. In some embodiments, waveguide devices utilize a Bragg grating (also called a volume grating). Bragg gratings have a high efficiency where less light is diffracted into higher orders. The relative amounts of diffracted and zero-order light can be varied by controlling the refractive index modulation of the grating, a property used to create lossy waveguide gratings for extracting light through a large pupil.

As used herein, the term grid encompasses, in some embodiments, a grid comprised of a set of grids. For example, in some embodiments, the input grating and/or the output grating individually include two or more gratings multiplexed into a single layer. It is well established in the holographic literature that more than one holographic prescription can be recorded in a single holographic layer. Methods for recording such multiplexed holograms are well known to those skilled in the art. In some embodiments, the input grating and/or output grating individually comprise two overlapping grating layers that are vertically separated or in contact with one or more thin optical substrates. In many embodiments, the grid layers are sandwiched between adjacent glass or plastic substrates. In some embodiments, two or more grating layers may form a stack such that total internal reflection occurs at external substrate and air interfaces. In many embodiments, the waveguide device may include only one grating layer. In some embodiments, electrodes are applied to the sides of the substrates to switch the diffraction gratings between a diffractive state and a clear state. According to many embodiments, the stack further includes additional layers such as beam splitting coatings and environmental protection layers.

In many embodiments, the grid layer is broken down into individual layers. According to various embodiments, multiple layers are stacked together on a single waveguide substrate. In some embodiments, the grating layer consists of several parts including an input coupler, a fold grating, and an output grating that are stacked together (or portions of which are stacked together) to form a single substrate waveguide. In many embodiments, portions of the waveguide devices are separated by optical glue or other transparent material, which has a refractive index that matches that of the portions. In many embodiments, the grating layer facilitates the cell fabrication process by vacuum filling each cell with a switchable Bragg grating (SBG) for each of the input coupler, fold grating, and output grating, thereby creating cells of a desired grating thickness. is formed through In many embodiments, the cell is formed by positioning multiple glass panes with gaps between the panes defining desired grating thicknesses for the input coupler, fold grating, and output grating. In many embodiments, a single cell is made of multiple openings so that the separate openings can be filled with different pockets of SBG material. Any intervening spaces according to various embodiments are separated by a separating material (eg, glue, oil, etc.) to define separate regions. In many embodiments, the SBG material is spin-coated on a substrate and then covered by a second substrate after curing of the material. By using a folded grating, the waveguide display advantageously requires fewer layers than conventional systems and methods of displaying information, according to some embodiments. Additionally, by using a folded grating, light can travel by total internal reflection within the waveguide in a single rectangular prism defined by the waveguide outer surfaces and simultaneously achieve double pupil expansion. In many embodiments, the input coupler and gratings can be created by interfering two light waves at an angle within the substrate to create a holographic wave front, thereby setting light and dark fringes on the waveguide substrate at the desired angle. can be created. In many embodiments, the grating of a given layer is recorded in a stepwise manner by scanning or stepping the recording laser beam across the grating area. In some embodiments, the gratings are recorded using mastering and contact copying processes currently used in the holographic printing industry.

In accordance with many embodiments the input and output gratings are designed to have a common surface grating pitch. In some embodiments, the input grating combines multiple gratings oriented such that each grating diffracts polarization of incident unpolarized light into the waveguide path. In many embodiments, the output grating combines a plurality of gratings oriented such that light from the waveguide paths is combined and combined outside the waveguide as unpolarized light. Each grating is characterized in 3D space by at least one grating vector (or K-vector), which in the case of a Bragg grating is defined as a vector perpendicular to the Bragg fringes. The grating vector determines the optical efficiency for a given range of input and diffracted angles.

One important class of gratings are known as Switchable Bragg Gratings (SBGs), which are used in various waveguide devices according to many embodiments. Typically, holographic polymer dispersed liquid crystals (HPDLC) are used in SBGs. In many embodiments, HPDLC includes mixed liquid crystals (LC), monomers, photoinitiator dyes, and coinitiators. Often, the mixture also includes a surfactant. Patents and scientific literature contain many examples of material systems and processes that can be used to manufacture SBGs. The two basic patents are: US Patent No. 5,942,157 to Sutherland and US Patent No. 5,751,452 to Tanaka et al. Both applications describe monomer and liquid crystal material combinations suitable for fabricating SBG devices. One of the known properties of transparent SBGs is that the LC molecules tend to align perpendicular to the lattice fringe planes. The effect of LC molecular alignment is that transmitting SBGs efficiently diffract P-polarized light (i.e., light with a polarization vector at the plane of incidence), but very little for S-polarized light (i.e., light with a polarization vector perpendicular to the plane of incidence). It has zero diffraction efficiency. Transmissive SBGs may not be used at near-grazing incidence as the diffraction efficiency of any grating for P polarization drops to zero when the included angle between incident and reflected light is small.

In many embodiments, SBGs are manufactured by first placing a thin film of a mixture of photopolymerizable monomers and liquid crystal material between parallel glass plates. One or two glass plates support electrodes for applying an electric field across the membrane. In many embodiments, the electrodes are made of an at least partially transparent indium tin oxide film. According to a number of embodiments, a volume phase grating may be recorded by illuminating a liquid crystal material (often referred to as a syrup) with two mutually coherent laser beams that interfere to form an inclined fringe grating structure. During the recording process the monomers polymerize and the mixture undergoes phase separation, producing regions densely packed by liquid crystal micro-droplets interspersed with regions of clear polymer, creating HPDLC. According to some embodiments, alternating liquid crystal-rich and liquid crystal-depleted regions of the HPDLC device form fringe planes of the grating. The resulting volume phase grating can exhibit very high diffraction efficiency, which can be controlled by the magnitude of the electric field applied across the film, according to various embodiments. When an electric field is applied to the grid through transparent electrodes, the natural orientation of the LC droplets changes, reducing the refractive index modulation of the fringes and dropping the holographic diffraction efficiency to very low levels. Typically, SBG devices switch clear in 30 μs, with longer relaxation times for switch-on. It should be noted that the diffraction efficiency of the device can be adjusted according to many embodiments by the applied voltage over a continuous range. The device exhibits nearly 100% efficiency when no voltage is applied, and efficiency is nearly zero when a sufficiently high voltage is applied. In certain embodiments of HPDLC devices, a magnetic field can be used to control LC orientation. In certain embodiments of HPDLC devices, phase separation of the LC material from the polymer can be achieved to the extent that no discernible droplet structure appears. In many embodiments, SBG is also used as a passive grating, which can provide the advantage of inherently high index of refraction modulation.

According to a number of embodiments, SBGs are used to provide transmissive or reflective gratings for free space applications. Various embodiments of SBGs are implemented as waveguide devices where the HPDLC forms a waveguide core or an evanescently coupled layer adjacent to the waveguide. In many embodiments, the parallel glass plates used to form the HPDLC cell provide a total internal reflection (TIR) light guiding structure. According to some embodiments, light is coupled outside the SBG when the switchable grating diffracts the light at an angle that exceeds the TIR condition.

In many embodiments of waveguide devices based on SBGs, the gratings are formed within a single layer sandwiched by transparent substrates. In many embodiments, the waveguide is only one grating layer. In various embodiments involving switchable gratings, transparent electrodes are applied to opposing surfaces of substrate layers sandwiching the switchable grating. In some embodiments, cell substrates are made of glass. An exemplary glass substrate is a standard Corning Willow glass substrate (index 1.51) available in thicknesses up to 50 microns. In many embodiments, the cell substrates are optical plastic.

It should be understood that Bragg gratings can also be recorded on other materials. In some embodiments, SBGs are recorded with a homogeneous modulating material, such as POLICRYPS or POLIPHEM, which has a solid liquid crystal matrix dispersed in a liquid polymer. In many embodiments, SBGs are not switchable (ie, passive). Non-switchable SBGs may have advantages over conventional holographic photopolymer materials that can provide high refractive index modulation due to their liquid crystalline content. Exemplary uniformly modulated liquid crystal-polymer material systems are disclosed in U.S. Patent Application Publication No. US2007/0019152 to Caputo et al. and PCT Application No. PCT/EP2005/006950 to Stump et al., both of which are incorporated herein by reference in their entirety. do. Uniform modulation gratings are characterized by high refractive index modulation (and therefore high diffraction efficiency) and low scatter. In many embodiments, at least one grating is a surface relief grating. In some embodiments, at least one grating is a thin (or Raman-Nath) hologram.

In many embodiments, the gratings are recorded with reverse mode HPDLC material. Reverse mode HPDLC differs from conventional HPDLC in that the grating is passive when no electric field is applied and diffracts in the presence of an electric field. Reverse mode HPDLC can be based on any of the recipes and processes disclosed in PCT Application No. PCT/GB2012/000680, entitled Improvements to Holographic Polymer Dispersed Liquid Crystal Materials and Devices. The grid can be recorded with any of the above-described material systems according to various embodiments, but is used in a passive (non-switchable) mode. The manufacturing process is the same as that used for switchable gratings, but the electrode coating step is omitted. LC polymer material systems are highly desirable given their high index modulation. In some embodiments, the gratings are recorded in HPDLC but are not switchable.

In some embodiments, the grating encodes optical power to adjust collimation of the output. In many embodiments, the output image is infinite. In many embodiments, the output image may be formed several meters away from the eye box.

In some embodiments, the input grating may be replaced with another type of input coupler. In certain embodiments, the input grating is replaced with a prism or reflective surface. In many embodiments, the input coupler may be a holographic grating, such as an SBG grating, which may or may not be switchable. The input coupler is configured to receive collimated light from the display source and cause the light to travel within the waveguide through total internal reflection between the first and second surfaces.

It is well established in the holography literature that more than one holographic prescription can be recorded in a single holographic layer. Methods for recording such multiplexed holograms are well known to those skilled in the art. In some embodiments, at least one of the input or output gratings combines two or more diffraction prescriptions to expand the angular bandwidth. In many embodiments, at least one of the input or output gratings combines two or more spectral diffraction prescriptions to extend the spectral bandwidth. In many embodiments, a color multiplexed grating is used to diffract two or more primary colors.

As described herein, many embodiments operate in monochrome. However, according to various embodiments of the present invention, the color waveguide includes a stack of monochromatic waveguides. In many embodiments, the waveguide device uses red, green, and blue waveguide layers. In some embodiments, the waveguide device uses red and blue/green layers. In some embodiments, the gratings are entirely passive. That is, it is not switchable. In many embodiments, at least one grid is switchable. In many embodiments, the input gratings of each layer are switchable to avoid color crosstalk between waveguide layers. In some embodiments, color crosstalk is prevented by placing dichroic filters between the red and blue input grating regions and the blue and green waveguides.

In many embodiments, light is characterized by wavelength bandwidth. In many embodiments, the waveguide device can vary the wavelength bandwidth of the light. According to various embodiments, Bragg gratings, which are inherently spectral bandwidth limiting devices, are most efficiently used in narrowband sources such as LEDs and lasers. According to many embodiments, a Bragg grating diffracts two different wavelength bands with high efficiency when the grating prescription and incident ray angles satisfy the Bragg equation. According to many embodiments, full color waveguides utilize separate specific wavelength layers, such as red, green, and blue diffractive waveguide layers. Two-layer solutions, where one layer diffracts two of the three primary colors, are used in many embodiments. In many embodiments, the natural spectral bandwidth of the Bragg grating is adequate to minimize color crosstalk. However, for more stringent suppression of color crosstalk, additional components may be used, such as dichroic filters and narrowband filters integrated between the waveguide layers and typically overlapping the input gratings.

Debanding Optics

In many embodiments, the debending optic is an effective input aperture, such that the input aperture is configured to provide a TIR angle (U) to the optical substrate when the optical substrate has a thickness (D), wherein the angle ( U) is calculated as 2D tan(U). Figure 2 is an embodiment of a waveguide device 110 comprising debending optics in the form of a waveguide comprising a waveguide substrate 111 and a TIR 1012 such that a condition of zero bending exists. In many embodiments, the condition of zero banding, i.e., that there is no gap between successive light extractions along the TIR ray path, is such that the effective input aperture for the waveguide substrate thickness (D) and TIR angle (U) is 2D tan( Occurs when given by U).

In some embodiments, debanding optics provide spatial variation of light along the TIR path in at least one of diffraction efficiency, light transmission, polarization, or birefringence. A typical spatial variation 120 is provided in the chart of FIG. 3 by curve 1020, where the Y axis represents the value of any of the above parameters (e.g. diffraction efficiency) and the This is the direction of beam propagation. In many embodiments, the spatial variation is two-dimensional (in the plane of the waveguide).

In some embodiments, the debanding optic is at least one grating configured to have multiple gratings, each grating providing a small pupil shift to eliminate or mitigate banding. In many embodiments, a stack of multiple gratings achieves small pupil shift when the separations between gratings within the stack are designed to provide pupil shift for each angle. In many embodiments, pupil shiftable gratings are separated by transparent substrates. In some embodiments, pupil shiftable gratings are passive. Alternatively, in some embodiments, the grids are switched on when a voltage is applied. In some embodiments, multiple gratings arranged with lateral relative displacement provide pupil shift. In many embodiments, multiple gratings are configured as a two-dimensional array with different sub-arrays of grating elements that switch into their diffraction states depending on the angle of incidence. In some embodiments, grids are configured as stacks of arrays. In various embodiments, separate gratings are provided for different wavelength bands. In many embodiments, the grid is multiplexed.

In many embodiments, the gratings have grating parameters that vary across the main plane of the waveguide. In some embodiments, the diffraction efficiency controls the amount of diffracted light relative to the amount of light transmitted along the waveguide as zero order light, allowing the uniformity of light extracted from the waveguide to be fine-tuned. ). In some embodiments, the K-vectors of at least one grating have rolled K-vectors with directions optimized to fine-tune the uniformity of light extracted from the waveguide. In various embodiments, the index modulation of the gratings is varied to fine-tune the uniformity of light extracted from the waveguide. In many embodiments, the thickness of the gratings is varied to fine-tune the uniformity of light extracted from the waveguide.

In many embodiments, the debending optics are at least one grating configured as a stacked switchable grating that turns on when a voltage is applied and shifts the pupil to eliminate or mitigate the banding effect. 4 shows an embodiment of a waveguide device 130 having an optical substrate 131 with stacked switchable input gratings 132A and 132B and a non-switchable output grating 133. Voltage supply 134 is coupled to input gratings 132A and 132B by electrical connections 135A and 135B to switch on input gratings 132A and 132B to provide pupil shift. Figure 5 shows an embodiment of a waveguide device 141 with a non-switchable input grating and a switchable output grating with stacked grating layers 143A and 143B. Voltage supply 144 is coupled to output gratings 143A and 143B by electrical connections 145A and 145B to switch on output gratings 143A and 143B to provide pupil shift. In various embodiments, a thin substrate layer is pulled between the stacked gratings to provide at least some separation.

In some embodiments, the debanding optical device includes at least one grating configured as an array of switchable grating elements that can turn on certain elements when a voltage is applied and shift the pupil to eliminate or mitigate banding effects. am. 6A illustrates a waveguide device 150 having an optical substrate 151 including input gratings 152A and 152B and output gratings 157 having a plurality of grating elements 153A-156A and 153B-156B, respectively. This is an example. The waveguide device includes a voltage supply coupled to each of the input gratings 152A and 152B by electrical connections 159A and 159B configured to individually switch on each element (e.g., 156A and 156B) to shift the pupil. 158) is further included. Although not shown, it should be understood that a voltage supply may be connected to each and every element to create an array of switchable elements. Additionally, although Figure 6A only shows the input grid being configured as an array, it should be understood that the output grid could also be an array of elements where each element is configured to be switchable in accordance with multiple embodiments of the present invention. do.

In various embodiments, the grid has multiple rolled K-vectors. The K-vector is a vector aligned perpendicular to the grating planes (or fringes) that determines the optical efficiency for a given range of input and diffracted angles. Rolled K-vectors according to many embodiments allow the angular bandwidth of the grating to be expanded without the need to increase the waveguide thickness. FIG. 6B shows an embodiment of a grating 152C with four rolled K-vectors (K ₁ -K ₄ ). In many embodiments, the grating is comprised of a two-dimensional array of switchable elements. For example, as shown in Figure 7, the grating is configured as a two-dimensional array 160 of switchable elements (eg, 161).

In many embodiments, the debending optical device is at least one grating configured to be a plurality of passive grating layers configured to shift the pupil to eliminate or mitigate banding effects. When the waveguide device includes multiple passive grating layers, according to various embodiments, its basic structure includes an active grating layer (see, e.g., FIGS. 4 and 5 ) without a voltage supply, some of which embodiments include Similar to In some embodiments, it is advantageous to use SBGs in a non-switchable mode to take advantage of the higher index modulation provided by multiple liquid crystal polymer material systems. In many embodiments, the debanding optic is at least one multiplexed diffraction grating configured to shift the pupil to eliminate or mitigate banding effects.

In some embodiments, the waveguide device includes a fold grating that provides exit pupil expansion. It should be understood that various fold gratings may be used in accordance with various embodiments of the present invention. Examples of various fold gratings that can be used in a number of embodiments are disclosed as described in PCT Application No. PCT/GB2016000181 entitled Waveguide Display or other references cited herein. According to some embodiments, the fold grating includes multiple gratings for pupil shifting to eliminate or mitigate banding effects, with each grating providing a small pupil shift.

In many embodiments, the debending optical device comprises one or more index layers disposed within an optical substrate such that the one or more index layers influence light ray paths within the optical substrate as a function of at least one of ray angle or ray position; , Shift the pupil to alleviate the banding effect. In some embodiments, at least one index layer is GRIN media. A variety of GRIN media may be used in accordance with various embodiments of the invention; examples of various GRIN media include, for example, U.S. Provisional Patent Application No. 62/123,282, entitled Near-Eye Display Using Gradient Index Optics, and Gradient Index Optics. It is disclosed in U.S. Provisional Patent Application No. 62/124,550 entitled Waveguide Display Using .

In many embodiments, the debending optical device comprises one or more index layers disposed adjacent to at least one reflective surface of an edge of an optical substrate, wherein the one or more layers are configured to provide pupil shift to eliminate or mitigate the effect of banding. do. 8 includes an input grating 172 and an output grating 173, with one or more stacked index layers 174 disposed adjacent the upper reflective surface of the waveguide such that the one or more stacked index layers provide pupil shifting. An embodiment of a waveguide device 170 having an optical substrate 171 that is shown is shown. In many embodiments, a debending optical device is one or more index layers disposed within an optical substrate, wherein the one or more layers are configured to provide pupil shifting to eliminate or mitigate banding effects. For example, FIG. 9 shows an input grating 182 and an output grating ( shows an embodiment of a waveguide device 180 with an optical substrate 181 comprising 183). In some embodiments, the waveguide device includes a debending optical device that includes one or more index layers disposed within an optical substrate and one or more index layers also disposed adjacent at least one reflective surface of the optical substrate.

In some embodiments, a debending optical device is an input grating having a leading edge capable of combining incident light, such that the inherent displacement of a bundle of light rays with respect to the leading edge of the input grating is determined by the input grating for any given incident light direction. provided, and shifts the pupil to eliminate or alleviate the banding effect. 10 is a detailed view of one embodiment of a waveguide device 190 having an optical substrate 191 including an input grating 192 with a leading edge 193. The collimated input ray paths for two different input angles 1090 and 1091 and the corresponding diffracted rays 1092 and 1093 are shown. The separation of the edges of the two sets of rays from the leading edge of input gratings 1094 and 1095 is shown. In some embodiments, displacement of the light relative to the edge of the input grating of the beam bundle causes a portion of the beam to fall outside the input grating apertures and thus not be diffracted into the TIR path inside the optical substrate depending on the field angle of the incoming light. . A suitable absorbing film captures non-diffracted light according to various embodiments. Therefore, as described in more detail with respect to Figure 2, when the waveguide substrate thickness (D) and TIR angle (U) are given by 2D tan(U), the beam width can be adjusted to meet the debanding condition. . An example of this embodiment will be discussed in more detail in a subsequent section (see Figure 20).

In many embodiments, a debanding optical device is an input grating configured to have a change in diffraction efficiency, such that a plurality of collimated incident ray paths of incident light are diffracted into different TIR ray paths as determined by the ray path input angle, A projected pupil may be formed at a unique location within the optical substrate for each of the plurality of collimated incident ray paths to eliminate or mitigate the banding effect. 11 is a detailed view of one embodiment of a waveguide device 200 having an optical substrate 201 including an input grating 202. The collimated input ray paths for two different input angles 1100 and 1101 are diffracted by the input grating 202 such that the diffracted rays 1102 and 1103 each follow a TIR path along the optical substrate 201. . Each TIR ray path 1104 and 1105 forms a projected pupil 1106 and 1107 at a unique location based on the angle of incidence, allowing banding effects to be eliminated and/or mitigated.

In some embodiments, the change in diffraction efficiency varies along the main waveguide direction to provide, at least in part, a pupil shift to eliminate or mitigate banding effects. In many embodiments, the change in diffraction efficiency varies in two dimensions across the aperture of the input grating.

In some embodiments, the debending optical device is a partially reflective layer disposed within an optical substrate, wherein the partially reflective layer separates incident light into transmitted and reflected light and shifts the pupil to eliminate or mitigate the banding effect. I order it. 12 is a detailed view of an embodiment of a waveguide device 210 with an optical substrate 211 comprising a partially reflective layer 212 capable of separating incident light 1110 into transmitted light 1000 and reflected light 1111. . Transmitted and reflected light 1000 and 1111 each follow a TIR path along the waveguide substrate 211, shifting the pupil to eliminate or mitigate the banding effect.

In many embodiments, a debending optical device is a polarization modifying layer disposed within an optical substrate, where the polarization modifying layer separates incident light into transmitted and reflected light and shifts the pupil to eliminate or mitigate banding effects. For example, Figure 13 provides a detailed view of one embodiment of a waveguide device 220 having an optical substrate 221 that includes a partially reflective polarization change layer 222, wherein the partially reflective polarization change layer is a polarization change layer ( It is separated into transmitted light 1121 and reflected light 1122 with polarization vector 1124 due to the delay effect of 222). Transmitted light 1121 and reflected light 1122 follow TIR paths along optical substrate 221 resulting in pupil shift to eliminate or mitigate the banding effect. In some embodiments, the polarization modifying layer is formed by stretching the polymer material in at least one dimension. In certain embodiments, the polarization modifying layer is a polymeric material, such as birefringent polyester, polymethylmethacrylate (PMMA), or poly-ethylene terephthalate (PET). Polymeric materials can be used as a single layer or two or more can be combined in a stack.

In many embodiments, the debending optics is at least one grating configured to provide at least two separate waveguide paths that eliminate or mitigate banding effects by eliminating non-uniformity in the extracted light for any angle of incident light. In some embodiments, the debanding optical device includes at least one grating with alternating tilt gratings used in conjunction with at least one folded grating exit pupil expander configured to provide pupil shift to eliminate or mitigate banding effects. 14 shows one embodiment of a waveguide device 230 with an optical substrate 231 coupled to an input image generator 232. The optical substrate 231 includes an input grating 233 with alternating tilt gratings 233A and 233B, a first folded grating comprising a grating 235, an exit pupil expander 234, and a second grating comprising a grating 237. It includes a folded grating exit pupil expander 236, and an output grating 238 with alternating slanted gratings 238A and 238B. Input grating 233 receives light from input image generator 232 in one direction 1130, which direction is perpendicular to the surface of input grating 233. In many embodiments, the intersecting gratings within the grating have a relative angle of about 90 degrees to the plane of the optical substrate. However, it should be noted that other angles may actually be used and are still included in various embodiments of the invention.

In some embodiments, the debanding optical device is a system of gratings, such that each of the input and output gratings combines intersecting gratings with peak diffraction efficiency for orthogonal polarization states. In some embodiments, the polarization states produced by the input and output gratings are S-polarization and P-polarization. In many embodiments, the polarization states produced by the input and output gratings are opposing senses of circular polarization. Some embodiments utilize gratings recorded in liquid crystal polymer systems, such as SBGs, which may have advantages due to their inherent birefringence and may exhibit strong polarization selectivity. However, it should be noted that other grating technologies that can be configured to provide unique polarization states can be used and are still included in various embodiments of the present invention.

Returning to Figure 14, the first polarization component of input light incident on input grating 233 along one direction 1130 is directed by grating 233B to the TIR path along direction 1131, and the second polarization component is directed to the TIR path along direction 1131. is directed by the second grating 233A to the second TIR path along direction 1132. Light traveling along TIR paths 1131 and 1132 is expanded in the plane of optical substrate 231 by fold gratings 234 and 236 and directed to second TIR paths 1133 and 1134 toward output grating 238. ) is diffracted. The alternating slopes 238A and 238B of the output grating 238 diffract light from the second TIR paths 1133 and 1134 into the uniform output path 1135 such that the banding effect is eliminated or mitigated. In some embodiments, the grating prescription is designed to provide dual interaction of the guided light with the grating, which can enhance the fold grating angular bandwidth. Many embodiments of dual interacting fold gratings can be used, such as the grating described in U.S. Patent Application No. 14/620,969 entitled Waveguide Grating Device.

In some embodiments, the debending optics include an optical component within the microdisplay that provides a variable effective numerical aperture (NA) that can be spatially varied along at least one direction to shift the pupil to eliminate or mitigate banding effects. am. 15 shows an input image generator 240 designed to have a smoothly varying numerical aperture (NA) over a range from high NA on one side to low NA on the other side of the micro display 241 panel to provide pupil shift. ) shows one example. For purposes of explanation, NA for a micro display is defined herein as being proportional to the sine of the maximum angle of the image ray cone from a point on the micro display surface with respect to the axis perpendicular to the micro display. do. As shown in FIG. 15 , the NA of the micro display 241 is spatially varied by the optical component 242, which allows the NA to be at least one part of the micro display as indicated by the elongated rays 1140-1142. Let it vary over one major dimension. The optical component used to change the NA may be any suitable optical component, such as any of the optical components described in PCT Application No. PCT/GB2016000181 entitled Waveguide Display. In many embodiments, a micro electromechanical system (MEMS) array is used to spatially vary the NA across the display panel of a micro display. In many embodiments, the MEM array spatially varies the NA of light reflected from the micro display panel. In many embodiments, the MEMS array utilizes technology used in data projectors.

In some embodiments, the micro display is a reflective device. In some embodiments, the micro display is a transmission device, such as a transmission liquid crystal on silicon (LCoS) device. In many embodiments, the input image generator has a transmissive micro-display panel with a backlight and a variable NA component. When a backlight is employed, according to various embodiments, the illuminated light typically has a uniform NA across the backside illuminating the backside of the microdisplay, which propagates through a variable NA component and moves along the main axis of the microdisplay. The output image with NA angles varying accordingly is converted into modulated light.

In many embodiments, an emissive display is used in a micro display. Examples of emissive displays for use within a microdisplay include, but are not limited to, LED arrays and light-emitting polymer arrays. In some embodiments, the input image generator integrates an emissive micro-display and a spatially varying NA component. According to various embodiments, light from a microdisplay employing an emissive display typically has a uniform NA across the emissive surface of the display, illuminates a spatially varying NA component, and has an NA that varies across the display aperture. The output image with the angles is converted into modulated light.

In many embodiments, the debanding optics comprise a plurality of grating layers within at least one grating, wherein the plurality of grating layers smear out any fixed pattern noise that results in pupil shift to eliminate or mitigate banding effects. It is configured to smear out. 16A is an embodiment of a waveguide device 250 having a picture generation unit (PGU) 251 optically coupled to an optical substrate 252 that extracts light through an output grating 253. Optical substrate 252 includes stacked input gratings 254 and 255 and a folded grating, not shown. Input light 1150 from PGU 251 is coupled to waveguide substrate 252 by input gratings 254 and 255, smearing out any fixed pattern noise, and directing to TIR paths 1151. diffracted into the light 1152 extracted by the output grating 253, resulting in a pupil shift, eliminating or mitigating the banding effect. In some embodiments, multiple gratings are combined into a multiplexed grating.

In some embodiments, the debanding optic is an input grating configured as an array of selectively switchable elements, wherein configuring the input grating as a switching grating array provides pupil switching in vertical and horizontal directions to eliminate banding effects. Shift the pupil to relax or relieve it. In many embodiments, individual grating elements are designed to diffract incident light from a predefined input beam angle range into a corresponding TIR angle range. 16B is an embodiment of a waveguide device 260 with a PGU 261 optically coupled to an optical substrate 262 extracting light through an output grating 253. Optical substrate 262 includes a switchable input grating array 264 of selectively switchable elements 265 . Input light 1160 is coupled to the optical substrate 262 by input grating 264, which is diffracted in vertical and horizontal directions into TIR paths 1161 and into light extracted by output grating 263. pupil shift, and the banding effect is eliminated or alleviated.

In many embodiments, the debanding optics provide spatial variations along each TIR path in at least one of diffraction efficiency, light transmission, polarization, and birefringence as a function of at least one of the light beam angle or light position within the substrate, the waveguide. A plurality of refractive index layers that affect the light ray paths within the substrate and shift the pupil to eliminate or mitigate the banding effect. In some embodiments, the plurality of refractive index layers include different indices of adhesive to particularly influence high angle reflections. In some embodiments, the plurality of refractive index layers include layers such as an alignment layer, an isotropic refractive layer, a GRIN structure, an anti-reflective layer, a partially reflective layer, or birefringent stretched polymer layers. 16C is an embodiment of a waveguide device 270 with a PGU 271 optically coupled to an optical substrate 272 that extracts light through an output grating 273. Optical substrate 272 includes input grating 274 and at least one refractive index layer 275. Input light 1170 is coupled to the optical substrate 272 by the input grating 275 and diffracted into TIR paths 1171 passing through the spatially varying refractive index layer 275 and then into the output grating 273. is diffracted into the light 1172 extracted by , resulting in a pupil shift that eliminates or alleviates the banding effect.

In some embodiments, the debending optics is a micro-display that projects spatially varying NAs that shift the pupil to eliminate or mitigate banding effects. In some embodiments, NA can vary in two orthogonal directions. 16D is an embodiment of a waveguide device 280 with a PGU 281 optically coupled to an optical substrate 282 extracting light through an output grating 283. Optical substrate 282 includes input grating 285 . Input light 1180 is coupled to the optical substrate 282 by input grating 285 and diffracted into TIR paths 1181 and then into extracted light 1182 by output grating 283. PGU 281 has a micro display 286 superimposed by an NA modification layer 287 that can spatially vary the NA and alter light with varying beam profiles 1184-1186, resulting in pupil shift. Eliminates or alleviates the banding effect. According to various embodiments, the PGU also integrates other components, such as projection lenses and/or beam splitters.

In many embodiments, the debending optics are inclined micro-displays configured to project an inclined rectangular exit pupil such that the cross-section of the exit pupil changes with field angle to eliminate or mitigate banding effects. In many embodiments, the exit pupil changes position on the input grating. This technique according to various embodiments can be used to address bending in one beam expansion axis. 16E is an embodiment of a waveguide device 290 with a PGU 291 optically coupled to an optical substrate 292 extracting light through an output grating 293. Input light 1190 emitted from the inclined PGU exit pupil 295 is coupled to the waveguide through input grating 294, diffracted into TIR paths 1191, and then extracted by output grating 293. (1192), which eliminates or alleviates the banding effect.

In some embodiments, the debending optical device is a tilting micro-display configured to tilt light rays to form various projected pupils at different locations along the optical substrate for each direction of incident light, wherein the bending effect occurs along one expansion axis. It is alleviated accordingly. 16F is one embodiment of a waveguide device 300 with a PGU 301 optically coupled to an optical substrate 302 extracting light through an output grating 303. Input light 1200 emitting from the inclined PGU exit pupil 305 is coupled to the waveguide by the input diffraction grating 304 and diffracted into TIR paths 1201. The guided light forms beam angle dependent projected cavities 1203 - 1205 at different locations along the substrate 302 for each direction of incident light, which is then extracted by the output grating 303 to produce light 1202 ), eliminating or mitigating the banding effect.

In many embodiments, the debending optical device is a prism coupled to an optical substrate, such that the linear relationship between the angles of the exit pupil from the light source and the TIR angles at the optical substrate is such that the TIR path angle is expressed by 2D tan(U). As defined, it does not create gaps between successive light extractions along the TIR ray path, which occurs when U. In many embodiments, the input grating is replaced with a coupling prism. In some embodiments, input light is provided through an inclined PGU pupil. By choosing the prism angle and the cooperative PGU pupil tilt, an approximately linear relationship can be achieved, according to various embodiments, between the angles outside the PGU exit pupil and the TIR angles of the waveguide and the waveguide substrate thickness (D) over the entire field of view. ) and the debanding condition is satisfied when the effective input aperture for the TIR angle (U) is given by 2D tan(U). 16G is an embodiment of a waveguide device 310 with a PGU 311 optically coupled to an optical substrate 312 extracting light through an output grating 313. Input light 1210 emitting from the inclined PGU exit pupil 315 is coupled to the optical substrate 312 by the prism 314 resulting in TIR paths 1211 and then by the output grating 293. It is diffracted into the extracted light 1192, eliminating or mitigating the banding effect. In some embodiments, color dispersion due to the prism is compensated for by the diffractive surface. In many embodiments, the prism coupler has refractive surface openings designed to shape light as a function of angle. Light at the edges of the beam that does not transmit through the prism into the waveguide is removed from the main light path by baffling or light absorbing coatings, according to many embodiments.

In some embodiments, the debending optical device is a light-absorbing film adjacent the edges of the optical substrate such that portions of incident light that would otherwise cause bending are removed to mitigate the banding effect. Figure 16h shows an embodiment of a waveguide device 320 designed for beam shifting along one beam expansion axis. The waveguide device includes a PGU (321) coupled to a waveguide (322) containing an output grating (323) and an input grating (324), a substrate (325) with a light absorbing film (326) applied to one of the edges, and a light absorbing film (325). 328 has a substrate 327 applied to one of its edges, with substrates 325 and 327 sandwiching a portion of the waveguide 322 containing the input grating. Input light at the upper limit of the input beam 1221 is diffracted by the input grating 324 into the TIR path 1223 and absorbed by the light absorbing film 326 applied to the substrate 325, resulting in a banding effect. eliminate or alleviate. Input light at the lower limit of the input beam 1222 is diffracted by the input grating 32 into the TIR path 1224 and absorbed by the light absorbing film 328 applied to the substrate 327, resulting in a banding effect. eliminate or alleviate. Input light near the center of the input beam 1220 is diffracted by the input grating 324 into a TIR path 1225 that does not interact with any of the light absorbing films 326 and 328, and the output grating 323 It continues to propagate under the TIR until extracted into the output beam 1226 by .

In many embodiments, the debending optical device includes an input grating and a first light-absorbing film disposed adjacent the edges of the input substrate disposed adjacent the optical substrate and adjacent the optical substrate opposite the input substrate. A second light-absorbing film disposed adjacent the edges of the second substrate disposed, wherein the incident light is continuous along the TIR ray path, which occurs when the TIR path angle is U as defined by 2D tan(U). It does not create gaps between light extractions. 17 shows one embodiment of a waveguide device 330 in which an input grating 334 is disposed within an input substrate 333 and the input grating is configured to sandwich a waveguide 331 with the substrate 332. A cross section of the input beam for a given viewing direction 1230 with peripheral rays 1231 and 1232 enters the input grating 334. The portion of the input beam bounded by rays 1233 and 1234 is diffracted into beam path 1236 and intercepted by absorbing film 335 applied to the edge of top substrate 332. The portion of the input beam bounded by rays 1232 and 1235 is diffracted into the beam path 1237 and is subjected to TIR at the outer surface of the top substrate 332, by an absorbing film 336 applied to the input substrate edge. blocked. The input beam portions bounded by rays 1231 and 1233 and 1234 and 1235 have respective TIR paths 1239 and 1240 that do not exhibit a gap or overlap in the beam cross-section area 1243 and in all subsequent beam cross-sections. and (1241 and 1242), thereby removing the banding using the TIR angle (U), and the waveguide substrate thickness (D) is given by 2D tan(U). In some specific embodiments, the thickness of the waveguide is 3.4 mm, the top substrate is 0.5 mm thick, and the bottom substrate includes two 0.5 mm thick glass substrates sandwiching the input grating. Based on this geometry and the debanding conditions of waveguide substrate thickness (D) and TIR angle (U) given by 2D tan(U), the throughput efficiency is approximately 1-2*0.5/(2*3.4 )= 84%, with little variation across the field of view.

In some embodiments using an input substrate, the input grating is implemented in individual cells bonded to the main waveguide, simplifying indium tin oxide (ITO) coating. In many embodiments utilizing an input substrate, a beam shifting technique based on forming a projected stop and tilting the PGU exit pupil is incorporated to provide debanding in orthogonal directions.

18 shows an embodiment of a waveguide device 340 having a waveguide portion 341, a prism 342 with two refractive surfaces inclined at a relative angle 1250, and an exit pupil 343 of a PGU (not shown). In detail, the exit pupil 343 is inclined at an angle 1251 relative to the reference axis 1252.

In some embodiments, the prism is separated from the waveguide by a small air gap. In many embodiments, the prism is separated from the waveguide by a thin layer of low index material.

Returning to FIG. 18 , light beams 1253 and 1254 from exit pupil 343 correspond to two different field angles refracted through prism 342 as beams 1255 and 1256 and then inside waveguide 341. are combined into TIR paths 1257 and 1258. The beam width at the waveguide surface adjacent to prisms 1259A and 1259B is shown. By choosing appropriate values for the prism angle, PGU exit pupil tilt angle, prism index, waveguide index and waveguide thickness and using that the TIR angle (U) and waveguide substrate thickness (D) are given by 2D tan(U), the light is It debands with respect to the field angles while simultaneously providing an approximately linear relationship between the field angle at the PGU exit pupil and the TIR angle in the waveguide for any ray in the field of view.

In many embodiments involving colored waveguides, projection stops are required to be created in each of the waveguides on a different plane, with the waveguides forming a stack. Misalignment of these stops results in misregistration of the color components of the output images from the waveguide and resulting color banding. One solution according to various embodiments is a waveguide input stop with outer dichroic portions to provide some compensation for color banding and to compensate for the phase shift due to the input stop. for internal phase compensation coating (eg SiO ₂ ). In some embodiments, the waveguide input stop has external dichroic portions, but no phase compensation coating. According to some embodiments the waveguide input stop is formed on a thin transparent plate adjacent the input surface of the waveguide and overlapping the input grating. In many embodiments, the waveguide input stop is located within a layer within the grating. In many embodiments, the waveguide input stop is placed directly adjacent to the outer surface of the waveguide.

When the pupil is projected at different positions along the optical substrate, according to various embodiments, color display application projection stops are created in different planes within the separate red, green and blue transmissive optical substrate layers. In some embodiments, the waveguide input stop includes external dichroic portions that shift the pupil and eliminate or mitigate color banding and interior phase compensation coated portions that compensate for the phase shift. In many embodiments, the internal phase compensation coating is SiO ₂ . 19 shows an embodiment of a waveguide input stop 350 with external dichroic portions 352 and 353 and internal phase compensation SiO ₂ coating 351 to shift the pupil and eliminate or mitigate color banding. .

In many embodiments, debending optics are input gratings configured such that light has a unique displacement relative to the edges of the input grating in any given incident light direction to shift the pupil, thereby eliminating or mitigating banding effects. The displacement of the light causes a portion of the light beam to fall outside the input grating openings and thus not be diffracted into the TIR path inside the waveguide, which varies with the field angle. In some embodiments, non-diffracted light may be trapped by a suitable absorbing film. In many embodiments, the beam width can be adjusted by displacement such that the TIR angle (U) and the waveguide substrate thickness (D) satisfy the debanding condition given by 2D tan(U). 20 is a detailed view of one embodiment of a waveguide device 360 having an optical substrate 361 including an input grating 362. The collimated input ray paths (1090 and 1091) and (1092 and 1093) for two different input angles are diffracted into rays (1094 and 1095) and (1096 and 1097). For each input beam angle, a portion of the input beam misses the input grating 362 and passes through the waveguide substrate 361 without exiting as rays 1098 and 1099 from each beam. In many embodiments, a light absorbing film applied to the waveguide surface traps non-diffracted light.

It should be understood that the various embodiments of debanding described herein may be combined. In some embodiments, embodiments of debanding may be combined with a technique that varies the diffraction efficiency of the input grating along the main waveguide direction. Additionally, in many embodiments, instances of debending are performed in each beam expansion direction. Accordingly, in some embodiments, two or more embodiments utilizing a debanding solution are combined to provide debanding in two dimensions. In many embodiments in which the waveguide device operates in two dimensions, the device includes fold gratings that allow debending in the two dimensions.

In many embodiments, the waveguide display is integrated with a window, such as a windscreen-integrated HUD for road vehicle applications. It should be understood that any suitable window-integrated display may be incorporated into the waveguide display and included in various embodiments of the present invention. Examples of window-integrated displays include U.S. Provisional Patent Application No. 62/125,064, entitled Optical Waveguide Displays for Integration into Windows, and U.S. Provisional Patent Application No. 62/125,066, entitled Optical Waveguide Displays for Integration into Windows. It is listed.

In many embodiments, the waveguide display includes gradient refractive index (GRIN) wave-guiding components to relay image content between the input image generator and the waveguide. Exemplary GRIN waveguide components are described in U.S. Provisional Patent Application No. 62/123,282, entitled Near-Eye Display Using Gradient Index Optics, and U.S. Provisional Patent Application No. 62/124,550, entitled Waveguide Display Using Gradient Index Optics. It is done. In some embodiments, the waveguide display includes a light pipe to provide beam expansion in one direction. Examples of light pipes are described in U.S. Provisional Patent Application No. 62/177,494, entitled Waveguide Device Incorporating Light Pipes. In some embodiments, the input image generator may be based on a laser scanner, such as disclosed in U.S. Patent No. 9,075,184, entitled Compact Edge-Illuminated Diffractive Display. Various embodiments of the present invention include, but are not limited to, HMDs for AR and VR, helmet-mounted displays, projection displays, head-up displays (HUDs), head-down displays (HDDs), autostereoscopic displays, and It is used in a wide range of displays, including other 3D displays. Many embodiments apply to waveguide sensors, such as eye trackers, fingerprint scanners, LIDAR systems, illuminators and backlights, for example.

In some embodiments, the waveguide device includes an eye tracker. It should be understood that multiple eye trackers may be used and still be included in various embodiments of the present invention, such as those described in PCT/GB2014/000197, entitled Holographic Waveguide Eye Tracker, and PCT/GB2014/000197, entitled Holographic Waveguide Optical Tracker. Includes eye trackers described in PCT Application No. GB2013/000210 entitled PCT/GB2015/000274 and Device for Eye Tracking.

It is emphasized that the drawings are illustrative and that the dimensions are exaggerated. For example, the thicknesses of the SBG layers were greatly exaggerated. Optical devices based on any of the foregoing embodiments may be implemented using plastic substrates using the materials and processes disclosed in PCT Application No. PCT/GB2012/000680, entitled Improvements to Holographic Polymer Disperse Liquid Crystal Materials and Devices. It can be. In some embodiments, the dual extended waveguide display can be curved.

The configuration and arrangement of the systems and methods as shown in the various example embodiments are illustrative only. Although only a few embodiments have been described in detail herein, many variations are possible (e.g., changes in size, dimensions, structure, shape and proportions of various elements, values of parameters, mounting arrangement, materials, color, orientation). use, etc.). For example, the positions of elements may be reversed or otherwise varied, and the nature or number of discrete elements or positions may be altered or varied. Accordingly, all such changes are intended to be included within the scope of this disclosure. The order or sequence of any process or method steps may be varied or rearranged according to alternative embodiments. Other substitutions, modifications, changes, and omissions may be made in the design, operating conditions, and arrangement of the exemplary embodiments without departing from the scope of the present disclosure.

Equivalence Principle

As can be inferred from the above description, the above-described concepts may be implemented in various configurations according to embodiments of the present invention. Accordingly, although the invention has been described in certain specific aspects, many additional modifications and variations will be apparent to those skilled in the art. Accordingly, it is to be understood that the invention may be practiced otherwise than as specifically described. Accordingly, the embodiments of the present invention should be considered in all respects as illustrative and not restrictive.

Claims (20)

In a waveguide device:
at least one optical substrate;
at least one light source;
By combining incident light from a light source with an angular bandwidth to total internal reflection (TIR) within the at least one optical substrate, a unique TIR angle is derived from each light incident angle as determined from the input grating. at least one optical coupler configured to diffract light from the at least one light source directly into the at least one optical substrate and having an effective input aperture. coupler; and
At least one light extractor extracting light from the optical substrate,
The effective input aperture W provides a TIR angle U to the optical substrate, and the TIR angle U, the effective input aperture W, and the thickness D of the optical substrate are related as W=2Dtan(U), such that the extracted light undergoes relaxed banding. A waveguide device that mitigates the banding effect of the illuminated pupil such that there is a substantially flat illumination profile with 2. The waveguide device of claim 1, wherein the extracted light has a spatial non-uniformity of less than 10% or less than 20%. According to claim 1,
at least one reflective surface on at least a portion of the edge of the optical substrate, and one or more index layers disposed adjacent to the at least one reflective surface where the one or more index layers are configured to shift the pupil to mitigate a banding effect. Including waveguide devices. According to claim 1,
The linear relationship between the angles of the exit pupil from the light source and the TIR angles at the optical substrate allows for continuous light extraction along the TIR ray path, which occurs when the TIR path angle is U as defined by 2Dtan(U). a prism coupled to the optical substrate that does not create gaps therebetween;
a first light-absorbing film comprising an input grating and disposed adjacent edges of an input substrate disposed adjacent an optical substrate, and adjacent edges of a second substrate disposed adjacent the optical substrate opposite the input substrate; A second light-absorbing film disposed so that the incident light does not create gaps between successive light extractions along the TIR ray path, which occurs when the TIR path angle is U, as defined by 2Dtan(U). the first light-absorbing film and the second light-absorbing film;
a first light-absorbing film comprising an input grating and disposed adjacent edges of an input substrate disposed adjacent an optical substrate, and adjacent edges of a second substrate disposed adjacent the optical substrate opposite the input substrate; A second light-absorbing film disposed so that the incident light does not create gaps between successive light extractions along the TIR ray path, which occurs when the TIR path angle is U as defined by 2Dtan(U), The thickness of the optical substrate is 3.4 mm, the thickness of the second substrate is 0.5 mm, and the input substrate comprises two 0.5 mm thick glass substrates sandwiching an input grating. light-absorbing membrane;
A waveguide device further comprising at least one selected from the group consisting of: According to claim 1,
The waveguide device is integrated into a display selected from the group of head-mounted displays (HMDs) and head-up displays (HUDs). According to claim 5,
the human eye is positioned with the exit pupil of the display; and wherein the device includes an eye tracker. According to claim 1,
A waveguide device, further comprising the light source, a micro display panel, and an input image generator further comprising optics for collimating the light. According to claim 1,
wherein the light source is selected from the group of at least one laser, and at least one light emitting diode (LED). According to claim 1,
wherein the optical coupler is selected from the group consisting of an input grating, and a prism. According to claim 1,
A waveguide device wherein the light extractor is an output grating. In a method of mitigating banding in the output light of a waveguide device:
generating incident light from a light source;
Passing the incident light through an optical coupler to couple the incident light to an optical substrate, wherein the coupled light undergoes total internal reflection (TIR) within the optical substrate, wherein the optical coupler combines light from at least one light source. passing the incident light, the incident light having an effective input aperture and configured to diffract directly into at least one optical substrate; and
extracting TIR light from the optical substrate via a light extractor to produce the output illumination;
The effective input aperture W provides a TIR angle U to the optical substrate, and the TIR angle U, the effective input aperture W, and the thickness D of the optical substrate are related as W=2Dtan(U), such that the extracted light undergoes relaxed banding. A method of mitigating banding in the output illumination of a waveguide device, wherein the banding effect of the illuminated pupil is mitigated such that the illumination profile is substantially flat with According to claim 11,
A method of mitigating banding in the output illumination of a waveguide device, wherein the output illumination has a spatial non-uniformity of less than 10% or less than 20%. According to claim 11,
the waveguide device comprising at least one reflective surface on at least a portion of the edge of the optical substrate, and one or more index layers disposed adjacent the at least one reflective surface configured to shift the pupil to mitigate banding effects. A method for mitigating banding in output illumination of a waveguide device, further comprising the above index layers. According to claim 11,
The waveguide device:
a prism coupled to the optical substrate, wherein a linear relationship between angles of the exit pupil from the light source and TIR angles at the optical substrate does not result in gaps between successive light extractions along the TIR ray path;
a first light-absorbing film disposed adjacent the edges of an input substrate disposed adjacent the optical substrate and comprising an input grating, wherein incident light does not create gaps between successive light extractions along the TIR light path; a second light-absorbing film disposed adjacent the edges of the second substrate disposed adjacent the optical substrate opposite the input substrate; and
The incident light does not create gaps between successive light extractions along the TIR light path, the optical substrate is 3.4 mm thick, the secondary substrate is 0.5 mm thick, and the input substrate is two 0.5 mm thick sandwiching the input grating. a first light-absorbing film disposed adjacent the edges of an input substrate disposed adjacent an optical substrate and comprising an input grating comprising mm-thick glass substrates and disposed adjacent the optical substrate opposite the input substrate; a second light-absorbing film disposed adjacent the edges of the second substrate;
A method for mitigating banding in output illumination of a waveguide device, further comprising at least one selected from the group consisting of: According to claim 11,
A method of mitigating banding in the output illumination of a waveguide device, the method being performed by a display selected from the group of a head mounted display (HMD) and a head up display (HUD). According to claim 15,
The human eye is positioned with the exit pupil of the display; and wherein the display includes an eye tracker. According to claim 11,
A method of mitigating banding in output illumination of a waveguide device, wherein the waveguide device further comprises an input image generator further comprising the light source, a micro display panel, and optics for collimating the light. According to claim 11,
A method of mitigating banding in the output illumination of a waveguide device, wherein the light source is selected from the group of at least one laser, and at least one light emitting diode (LED). According to claim 11,
A method of mitigating banding in output illumination of a waveguide device, wherein the optical coupler is selected from the group consisting of an input grating and a prism. According to claim 11,
A method of mitigating banding in the output illumination of a waveguide device, wherein the light extractor is an output grating.

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