Holographic virtual reality display

Virtual reality (VR) displays are computer displays that present images or video in a manner that simulates a real experience for the viewer. In many cases, VR displays are implemented as head-mounted displays (HMDs) which provide a display in the line of sight of the user. Because current HMDs are composed of a display panel and magnifying lens with a gap therebetween, proper functioning of the HMDs limits their design to a box-like form factor, thereby negatively impacting both comfort and aesthetics. The present disclosure provides a different configuration for a virtual reality display which allows for improved comfort and aesthetics, including specifically at least one coherent light source, at least one holographic waveguide coupled to the at least one coherent light source to receive light therefrom, and at least one spatial light modulator coupled to the at least one holographic waveguide to modulate the light.

TECHNICAL FIELD

The present disclosure relates to virtual reality displays.

BACKGROUND

Virtual reality (VR) displays are computer displays that present images or video in a manner that simulates a real experience for the viewer. For example, VR displays may present a three-dimensional (3D) environment, which may or may not be interactive. VR displays are useful for various applications that employ VR, such as entertainment (e.g. video games), education (e.g. training), and business (e.g. meetings), etc.

In many cases, VR displays are implemented as head-mounted displays (HMDs). HMDs are, by definition, worn on the head of a user to provide a display in the line of sight of the user. By viewing the display, the user is able to experience VR. In an effort to encourage more widespread use of HMDs, it has been important to focus HMD designs on more comfortable form factors, higher performance, and improved aesthetics.

To date, however, the typical configuration of HMDs limits their comfort and aesthetics. In particular, a HMD is currently composed of a display panel and magnifying lens (i.e. eye piece). In order to provide a perceptible image to the user, the distance between the display panel and the lens should be slightly smaller than the focal length of the lens. Since it is not feasible to make a very short focal length lens in a given aperture size, current HMDs have a box-like form factor and accordingly do not replicate the traditional form of eye glasses, which negatively impacts both their comfort and aesthetics.

There is a need for addressing these issues and/or other issues associated with the prior art.

SUMMARY

An apparatus and associated method are disclosed for a holographic virtual reality (VR) display. The VR display includes at least one coherent light source, at least one holographic waveguide coupled to the at least one coherent light source to receive light therefrom, and at least one spatial light modulator coupled to the at least one holographic waveguide to modulate the light.

DETAILED DESCRIPTION

FIG.1illustrates a holographic VR display100having a coherent light source, a holographic waveguide, and a spatial light modulator, in accordance with an embodiment. In the context of the present description, the holographic VR display100is a device configured to display VR images and/or VR video for viewing by a user. In one embodiment, the holographic VR display100may be a HMD capable of being worn on a head of the user to provide the display in the line of sight of the user.

As shown, the VR display100includes at least one coherent light source102, at least one holographic waveguide104, and at least one spatial light modulator106. While these elements of the holographic VR display100are described below as being coupled (and shown to be directly coupled), at least in part, to one another, it should be noted that in the context of the present description, the term “coupled” may refer to any direct coupling (i.e. with nothing therebetween), any indirect coupling (i.e. with one or more elements or space situated therebetween), partial coupling, completing coupling, and/or any other coupling capable of connecting different elements. Any gaps or space between elements may be unfilled (e.g. composed of air) or may be filled with some substance, such as an anti-reflective coating.

Also in the context of the present description, a coherent light source102refers to any light source that is capable of outputting light of any type (e.g. plain, encoded with data, etc.) that is at least partially coherent (e.g. only partially coherent, completely coherent, etc.). Coherent light may refer to a beam of photons that, at least in part, have the same frequency, such as a laser beam output by a laser source. In one embodiment, the VR display100may include a single coherent light source102, optionally with the capability to output light in a plurality of different colors. In another embodiment, the VR display100may include a plurality of coherent light sources102, each capable of outputting light in a different color. In the case of a plurality of coherent light sources102, the coherent light sources102may be time-multiplexed such that light is output by the coherent light sources102in a time-multiplexed manner.

In one embodiment, the coherent light source102may include a point light source that emits the light, a concave mirror that reflects the light emitted by the point light source, and a beam splitter that directs the light reflected by the concave mirror.

The coherent light source102is coupled to at least one holographic waveguide104such that the at least one holographic waveguide104receives light from the coherent light source102. For example, the aforementioned beam splitter may direct the light reflected by the concave mirror to the holographic waveguide104. In the context of the present description, a holographic waveguide104refers to any waveguide (which may include a lightguide) that includes at least one holographic element or function. For example, the holographic waveguide104may use the at least one holographic element or function to direct the light received from the coherent light source102(e.g. as shown by the arrows inFIG.1directing the light received from the coherent light source102).

In one embodiment, the at least one holographic waveguide104may include a backlight holographic waveguide. For example, the backlight holographic waveguide may include a plurality of mirrors to direct the light received from the coherent light source102towards at least one spatial light modulator106, as described in more detail below. In another embodiment, the at least one holographic waveguide104may include a holographic waveguide with at least one waveguide coupler. For example, the at least one holographic waveguide104may include a holographic waveguide with a waveguide in-coupler, and a waveguide out-coupler. The waveguide in-coupler may refract light received from the coherent light source102to cause it to travel through the holographic waveguide104to the waveguide out-coupler which may in turn direct the light towards the at least one spatial light modulator106, again as described in more detail later.

In any case, the holographic waveguide104may be configured such that coherence of the light output by the coherent light source102is maintained, at least in part, when traveling through the holographic waveguide104. Additionally, the holographic waveguide104may be configured such that polarization of the light output by the coherent light source102is maintained, at least in part, when traveling through the holographic waveguide104. Further, the holographic waveguide104may be configured such that a direction of the light (which may be perpendicular to the holographic waveguide104), when output by the holographic waveguide104, is maintained at least in part.

The at least one holographic waveguide104is coupled to at least one spatial light modulator106to modulate the light. In the context of the present description, a spatial light modulator106refers to any device or component that at least partially spatially varies a modulation of light. Accordingly, the spatial light modulator106may impose, at least in part, a spatially varying modulation on the light transmitted (e.g. output) by the holographic waveguide104. In one embodiment, the at least one spatial light modulator106may be directly coupled to the at least one holographic waveguide104with no space (i.e. gap) therebetween. In one embodiment, the at least one spatial light modulator106may be indirectly coupled to the at least one holographic waveguide104with a space (and/or some other material) therebetween.

The spatial light modulator106may be the display plane of the VR display100. In an embodiment, the spatial light modulator106may create the VR image or video behind the spatial light modulator106(from the point of view of an eye of the user of the VR display100). In another embodiment, the spatial light modulator106may be a reflective spatial light modulator106. In an embodiment, the spatial light modulator106is driven using pixel data received from an image source. As an option, a receiver of the VR display100may receive the pixel data from a remote source. Of course, in another embodiment the pixel data may be generated locally with respect to the VR display100.

By this configuration of the VR display100, any gap between the at least one holographic waveguide104and at least one spatial light modulator106may be reduced or eliminated. As a result, a cross-sectional thickness of the VR display100, or in particular a combined cross-sectional thickness of the at least one holographic waveguide104and at least one spatial light modulator106, may be less than 10 millimeters (mm) in one embodiment. In another embodiment, the cross-sectional thickness of the VR display100, or in particular a combined cross-sectional thickness of the at least one holographic waveguide104and at least one spatial light modulator106, may be less than 7 mm. In still other embodiments, such combined cross-sectional thickness may be less than 9 mm, 8 mm, etc.

Furthermore, even with the reduced or eliminated gap mentioned above, a quality of VR images and/or video displayed by the VR display100may be improved with regard to traditional VR displays. In one embodiment, this may be achieved by using a coherent light source102with a coherent length that is larger than a length of the spatial light modulator106, thereby ensuring light interference. Still yet, the above described configuration of the VR display100may support three-dimensional (3D) VR images and/or video. For example, the spatial light modulator106may be capable of displaying 3D images and/or video behind the spatial light modulator106plane (virtual).

As an option, the VR display100may be configured such that the light is not polarized. As another option, the VR display100may be configured such that the light is polarized. As yet another option, the VR display100may not necessarily include a beam splitter. As still yet another option, the VR display100may be filterless, and for example may rely on a propagation pipeline that uses simulation to determine a phase and amplitude to be used by the spatial light modulator106.

It should be noted that while VR display100is described above as including a coherent light source102, a holographic waveguide104, and a spatial light modulator106, other embodiments are contemplated in which a VR display includes additional elements.FIGS.2-7described below provide other possible embodiments of a VR display. Just by way of example, in one embodiment a VR display may include at least one magnifying lens (e.g. see at leastFIG.2), which may be a Fresnel lens or a holographic lens. In another embodiment, a VR display may include at least one polarization element coupled between the at least one magnifying lens and the at least one holographic waveguide (e.g. seeFIG.4). In yet another embodiment, a VR display may include at least one quarter-wave element coupled between the at least one holographic waveguide and the at least one spatial light modulator (e.g. seeFIG.4). Moreover,FIG.10describes a method of operation of a HMD configured according to one or more of the embodiments described herein.

More illustrative information will now be set forth regarding various optional architectures and features with which the foregoing framework may be implemented, per the desires of the user. It should be strongly noted that the following information is set forth for illustrative purposes and should not be construed as limiting in any manner. Any of the following features may be optionally incorporated with or without the exclusion of other features described. For example, in one embodiment, the VR display100may include a receiver that receives pixel data (e.g. representing the VR images or VR video) from a remote source over a network, for display via the holographic VR display100. The remote source may be any computer system capable of transmitting the pixel data to the VR display100via the network. For example, the remote source may be a server, video game console, mobile device (e.g. of a user), or any other computer system, such as that described below with reference toFIG.9. The VR display100may use a wired or wireless connection to the network in order to receive the pixel data from the remote source.

FIG.2illustrates a VR display200having a coherent light source, a holographic waveguide, a spatial light modulator, and a magnifying lens, in accordance with an embodiment. It should be noted that the aforementioned definitions and/or description may equally apply to the description below.

As shown, at least one holographic waveguide104is coupled to at least one coherent light source102to receive light therefrom. Additionally, at least one spatial light modulator106is coupled to a first face of the at least one holographic waveguide104to modulate the light. Further, with respect to the present embodiment, at least one magnifying lens108is coupled to a second face of the at least one holographic waveguide104that is opposite the first face of the at least one holographic waveguide104. The magnifying lens108may be coupled to a user-facing side of the holographic waveguide104. The at least one magnifying lens108may be a Fresnel lens in one embodiment. In another embodiment, the at least one magnifying lens108may be a holographic optical element. In yet another embodiment, the at least one magnifying lens108may be a diffractive optical element. In still yet another embodiment, the at least one magnifying lens108may be a meta-surface.

The at least one magnifying lens108may be an element of the VR display200that is viewed by a user of the VR display200. For example, the modulated light may be transmitted from the at least one spatial light modulator106to the at least one magnifying lens108for output to an eye110of the user of the VR display200. The magnifying lens108may magnify the VR image and/or video, where a focal length of the magnifying lens108may larger, at least slightly, than a distance between the at least one spatial light modulator106and the focusing optics. Incorporation of the magnifying lens108in the VR display200may widen the field of view for the user.

FIG.3illustrates an implementation300of a VR display having a coherent light source, a holographic waveguide, a spatial light modulator, and a magnifying lens, in accordance with an embodiment. For example, the implementation300may include VR display200ofFIG.2. It should be noted that the aforementioned definitions and/or description may equally apply to the description below.

As shown, at least one holographic waveguide104is coupled to at least one coherent light source102to receive light therefrom. Additionally, at least one spatial light modulator106is coupled to a first face of the at least one holographic waveguide104to modulate the light. Further, with respect to the present embodiment, at least one at least one magnifying lens108is coupled to a second face of the at least one holographic waveguide104that is opposite the first face of the at least one holographic waveguide104.

The at least one magnifying lens108is an element of the VR display200that is viewed by the eye110of a user of the VR display200. In particular, in the present embodiment the modulated light may be transmitted from the at least one spatial light modulator106to the at least one magnifying lens108for output to the eye110of the user of the VR display200.

In the present embodiment, light is transmitted by the at least one coherent light source102through the at least one holographic waveguide104. The light output by the at least one holographic waveguide104is in turn transmitted to the spatial light modulator106for modulation thereof. The modulated light output by the spatial light modulator106is then transmitted through the magnifying lens108for output to the eye110of the user.

In the context of the present embodiment, the total image distance (d_tot) supported by the VR display is calculated as a function of the distance between the at least one magnifying lens108and the eye (e.g. pupil) of the user (i.e. eye relief e), the distance between the at least one magnifying lens108and the focusing optics (i.e. focal length f), and the distance between the at least one spatial light modulator106and the focusing optics (i.e. SLM image distance d). Table 1 illustrates an equation that may be used to calculate the total image distance (d_tot), by way of example.
d_tot=(f/[f−d])d+eTable 1

FIG.4illustrates an implementation400of a VR display having a coherent light source, a holographic waveguide, a spatial light modulator, a magnifying lens, and a polarizer, in accordance with an embodiment. It should be noted that the aforementioned definitions and/or description may equally apply to the description below.

As shown, at least one holographic waveguide104is coupled to at least one coherent light source102to receive light therefrom. Additionally, at least one spatial light modulator106is indirectly coupled to a first face of the at least one holographic waveguide104to modulate the light. Situated (coupled) between the at least one spatial light modulator106and the at least one holographic waveguide104is a quarter-wave plate114. Further, with respect to the present embodiment, at least one at least one magnifying lens108is indirectly coupled to a second face of the at least one holographic waveguide104that is opposite the first face of the at least one holographic waveguide104. Situated (coupled) between the at least one at least one magnifying lens108and the at least one holographic waveguide104is a polarizer112.

The at least one magnifying lens108is an element of the VR display200that is viewed by the eye110of a user of the VR display200. In particular, in the present embodiment the modulated light may be transmitted from the at least one spatial light modulator106through the polarizer112and quarter-wave plate114to the at least one magnifying lens108for output to the eye110of the user of the VR display. The combination of the polarizer112and quarter-wave plate114functions to improve image contrast.

In the present embodiment, light is transmitted by the at least one coherent light source102through the at least one holographic waveguide104. The light output by the at least one holographic waveguide104is in turn transmitted through the quarter-wave plate114to the spatial light modulator106for modulation thereof. The modulated light output by the spatial light modulator106is then transmitted back through the quarter-wave plate114and in turn through the polarizer112in order to polarize the modulated light. The polarized and modulated light is transmitted through the magnifying lens108for output to the eye110of the user.

Similar to implementation300ofFIG.3, in the context of the present embodiment the total image distance (d_tot) supported by the VR display200is calculated as a function of the distance between the at least one magnifying lens108and the eye (e.g. pupil) of the user (i.e. eye relief e), the distance between the at least one magnifying lens108and the focusing optics (i.e. focal length f), and the distance between the at least one spatial light modulator106and the focusing optics (i.e. SLM image distance d). For example, Table 1 above illustrates an equation that may be used to calculate the total image distance (d_tot) for implementation400.

FIG.5illustrates an implementation500of a VR display having a coherent light source, a holographic waveguide, and an adjacent magnifying lens and spatial light modulator, in accordance with an embodiment. It should be noted that the aforementioned definitions and/or description may equally apply to the description below.

As shown, at least one holographic waveguide104is coupled to at least one coherent light source102to receive light therefrom. Additionally, at least one spatial light modulator106is indirectly coupled to a first face of the at least one holographic waveguide104to modulate the light. Situated (coupled) between the at least one spatial light modulator106and the at least one holographic waveguide104is a magnifying lens116. As opposed to the embodiments of other Figures described herein, the present implementation500of the VR display does not include a magnifying lens on the face of the at least one holographic waveguide104facing the user (i.e. opposite the first face of the at least one holographic waveguide104). Instead, in the present embodiment the magnifying lens116may be located behind the holographic waveguide104, from the perspective of the user.

In the present embodiment, light is transmitted by the at least one coherent light source102through the at least one holographic waveguide104. The light output by the at least one holographic waveguide104is in turn transmitted through the magnifying lens116to the spatial light modulator106for modulation thereof. The modulated light output by the spatial light modulator106is then transmitted back through the magnifying lens116for output to the eye110of the user.

Similar to implementation300ofFIG.3, in the context of the present embodiment the total image distance (d_tot) supported by the VR display is calculated as a function of the distance between the at least one magnifying lens108and the eye (e.g. pupil) of the user (i.e. eye relief e), the distance between the at least one magnifying lens108and the focusing optics (i.e. focal length f), and the distance between the at least one spatial light modulator106and the focusing optics (i.e. SLM image distance d). For example, Table 1 above illustrates an equation that may be used to calculate the total image distance (d_tot) for implementation500.

FIG.6Aillustrates an implementation600of a VR display having a coherent light source, a holographic waveguide with in-coupler and out-coupler, a magnifying lens, and a spatial light modulator, in accordance with an embodiment. It should be noted that the aforementioned definitions and/or description may equally apply to the description below.

As shown, at least one holographic waveguide118is coupled to at least one coherent light source102to receive light therefrom. The at least one holographic waveguide118has an in-coupler120and out-coupler122. The in-coupler120directs the light from the light source102into the at least one holographic waveguide118and the out-coupler122directs the light out of the at least one holographic waveguide118. Additionally, at least one spatial light modulator106is coupled to a first face of the at least one holographic waveguide104. Further, with respect to the present embodiment, at least one at least one magnifying lens108is indirectly coupled to a second face of the at least one holographic waveguide104that is opposite the first face of the at least one holographic waveguide104. In the present embodiment, as shown, the out-coupler122is situated (coupled) between the at least one at least one magnifying lens108and the at least one holographic waveguide118.

In the present embodiment, light is transmitted by the at least one coherent light source102and is directed by the in-coupler120to the at least one holographic waveguide118. The out-coupler122directs the light out of the at least one holographic waveguide118to the spatial light modulator106for modulation thereof. Thus, the spatial light modulator106may be located on the out-coupler122side of the holographic waveguide118. The modulated light output by the spatial light modulator106is then transmitted through the at least one at least one magnifying lens108for output to the eye110of the user.

Similar to implementation300ofFIG.3, in the context of the present embodiment the total image distance (d_tot) supported by the VR display is calculated as a function of the distance between the at least one magnifying lens108and the eye (e.g. pupil) of the user (i.e. eye relief e), the distance between the at least one magnifying lens108and the focusing optics (i.e. focal length f), and the distance between the at least one spatial light modulator106and the focusing optics (i.e. SLM image distance d). For example, Table 1 above illustrates an equation that may be used to calculate the total image distance (d_tot) for implementation600.

FIG.6Billustrates an implementation of the holographic waveguide ofFIG.6A, in accordance with an embodiment. As shown, the in-coupler120directs the light (from the light source102) into the at least one holographic waveguide118and the out-coupler122directs the light out of the at least one holographic waveguide118.

FIG.7illustrates an implementation700of a VR display having a coherent light source, a holographic waveguide, and a spatial light modulator, in accordance with an embodiment. For example, the implementation700may include VR display100ofFIG.1. It should be noted that the aforementioned definitions and/or description may equally apply to the description below.

As shown, at least one holographic waveguide104is coupled to at least one coherent light source102to receive light therefrom. Additionally, at least one spatial light modulator106is coupled to a first face of the at least one holographic waveguide104to modulate the light. The first face is opposite a second face of the at least one holographic waveguide104facing an eye100of a user of the VR display.

In the present embodiment, light is transmitted by the at least one coherent light source102through the at least one holographic waveguide104. The light output by the at least one holographic waveguide104is in turn transmitted to the spatial light modulator106for modulation thereof. The modulated light is output by the spatial light modulator106for viewing by the eye110of the user.

In the context of the present embodiment, the total image distance (d_tot) supported by the VR display is calculated as a function of the distance between the at least one magnifying lens108and the eye (e.g. pupil) of the user (i.e. eye relief e), the distance between the at least one magnifying lens108and the focusing optics (i.e. focal length f), and the distance between the at least one spatial light modulator106and the focusing optics (i.e. SLM image distance d). For example, Table 1 above illustrates an equation that may be used to calculate the total image distance (d_tot) for implementation700.

FIG.8Aillustrates an implementation800of the components of a coherent light source that is coupled to a holographic waveguide, in accordance with an embodiment. For example, the implementation800may be included in VR display100ofFIG.1. It should be noted that the aforementioned definitions and/or description may equally apply to the description below.

As shown, a holographic waveguide104is coupled to a coherent light source102to receive light therefrom. The coherent light source102includes a point light source802that emits the light. The point light source802may be any light emitting device that outputs a beam of light, which may be narrow. For example, the point light source802may be a laser source that generates and outputs a laser beam.

The point light source802is coupled to a concave mirror804that reflects the light emitted by the point light source802. Thus, the point light source802is situated to emit the light in a direction toward the concave mirror804. The concave mirror804may also be configured to collimate the light received from the point light source802. The concave mirror804is coupled to a beam splitter806that directs the light reflected by the concave mirror804to the holographic waveguide104. Thus, the beam splitter806is situated with respect to the concave mirror804and the holographic waveguide104such that the beam splitter806receives the light reflected by the concave mirror804and directs the light to (e.g. an in-coupler of) the holographic waveguide104.

The components of the coherent light source102, as illustrated herein, may operate to expand and collimate the light emitted by the point light source802and to direct the light to the holographic waveguide104. It should be noted that the materials, angles, lengths, and/or any other features of the components of the coherent light source102may be configured as desired to achieve the output of light, that is at least partially coherent, to the holographic waveguide104. The holographic waveguide104includes at least one holographic element or function to direct the light received from the coherent light source102through the holographic waveguide104to an output (e.g. out-coupler) of the holographic waveguide104. In the present embodiment shown, the holographic waveguide104includes an array of partial mirrors808configured to output the light.

In an embodiment, the multiple prism structure inside the holographic waveguide104can create a ghost image and may result in additional image degradation. As an option, the wavelengths of the lightguide (i.e. with half mirrors) or the waveguide [diffractive optical element (DOE)-based or holographic optical element (HOE)-based] may be matched with the input coherent light source102(e.g. in 3 colors (R,G,B)) to avoid the ghost image/image degradation. Otherwise, a different holographic waveguide configuration may be used.

FIG.8Billustrates a modified implementation850of the implementation800ofFIG.8A, which further includes a geometric phase lens and a quarter wave plate, in accordance with an embodiment. Thus, the description ofFIG.8Amay equally apply to the present embodiment illustrated inFIG.8B.

As shown, the holographic waveguide104is coupled to a geometric phase lens810on one side and a quarter wave plate812on the other side with the spatial light modulator106. The quarter wave plate812is situated between the holographic waveguide104and the spatial light modulator106.

The geometric phase lens810and the quarter wave plate812may be included for the implementation800ofFIG.8Aas an alternative to the combination of a Fresnel lens and linear polarizer (e.g. as illustrated inFIG.4). For example, in the context of the implementation800ofFIG.8A, use of a Fresnel lens may cause holographic images to not be seen without a linear polarizer, since the linear polarization look differently after the folded optical path. The incident light to the spatial light modulator106should have a certain polarization (e.g. linearly polarized in a 45-degree slanted direction) and, when using a Fresnel lens, another linear polarizer may be needed to observe the holographic images. Furthermore, the saw-tooth pattern on the Fresnel lens surface may create a high frequency noise pattern with the coherent light source102in which it will be unsuitable for use in displaying holographic images.

Use of the geometric phase lens810and the quarter wave plate812, as illustrated in the modified implementation850ofFIG.8B, avoids the above noted issues associated with the Fresnel lens and linear polarizer combination.

FIG.9illustrates a propagation pipeline900for optimizing a spatial light modulator, in accordance with an embodiment. The propagation pipeline900may be used to optimize the spatial light modulator of any of the previous Figures and/or embodiments. Again, It should be noted that the aforementioned definitions and/or description may equally apply to the description below.

In a holographic VR display (e.g. seeFIG.1), a spatial light modulator programmatically modulates the phase of light (e.g. polarized laser illumination). The resulting phase modulated wavefront output by the spatial light modulator propagates to a target volume where interference produces a desired output (e.g. image or 3D scene). Thus, an algorithm is used to compute a phase pattern to be used by the spatial light modulator to produce the desired output.

Typically, the finite pixel pitch of the spatial light modulator will result in higher order diffractive copies which overlap with the desired image and reduce the image quality. To date, an aperture has been required to remove these copies (i.e. to block, filter, etc. the higher orders).

The present propagation pipeline900allows for a filterless implementation of a holographic VR display, even for example where the spatial light modulator produces the higher order copies. At the start of the propagation pipeline900, a complex wavefront at the spatial light modulator is simulated using a phase pattern and unit amplitude. This is fourier transformed (FT) to move to the frequency domain, illustrated as the FFT amplitude and FFT phase.

The frequency domain is repeated to produce the higher order copies (illustrated as the repeating FFT amplitude and FFT phase copies). The propagation is then performed by multiplying the wavefront by a 2D sinc amplitude, which accounts for the finite pixel pitch of the spatial light modulator, and an angular spectrum method (ASM) phase delay, thus resulting in the propagation FFT amplitude and propagation FFT phase. The output of the propagation pipeline900is computed by converting the propagation FFT amplitude and the propagation FFT phase back from the frequency domain, to produce the propagation amplitude and propagation phase to be used by the spatial light modulator.

The use of the repeated frequency domain and the 2D sinc amplitude, together, produce a propagation pipeline that accurately simulates the higher orders. In this way, the spatial light modulator may be optimized with the propagation amplitude and propagation phase such that the desired output is produced by the spatial light modulator. Using this propagation pipeline900, image quality can be improved when optical filtering is not present in the holographic VR display. Removing the need for the optical filter may in turn enable a more compact holographic VR display without sacrificing image quality. Further, utilizing the light from the higher orders will increase the etendue of the holographic VR display without adding additional hardware components.

FIG.10illustrates a method1000of operation of a HMD, in accordance with an embodiment. In one embodiment, the method1000may be carried out using the implementation700of VR display (described inFIG.7) as the HMD, such that the HMD includes at least one coherent light source, at least one holographic waveguide (e.g. backlight holographic waveguide, holographic waveguide with at least one waveguide coupler, holographic waveguide including a waveguide in-coupler, and a waveguide out-coupler, etc.) coupled to the at least one coherent light source, and at least one spatial light modulator coupled to the at least one holographic waveguide (e.g. with no space therebetween). As an option, in the context of the HMD of the present embodiment, a combined cross-sectional thickness of the at least one holographic waveguide and the at least one spatial light modulator may be less than 10 mm, or in some embodiments less than 7 mm.

In other embodiments, HMD may be an augmented reality (AR) display or a mixed reality (MR) display. Thus, HMD may not necessarily be limited to a VR display, but, with a similar configuration to the VR display100ofFIG.1, the HMD may also include a camera for capturing live images in order to create AR or MR images and/or video. Of course, any of the embodiments described above with respect to the various Figures may be employed in the context of the HMD performing the present method800.

In operation1002, light from the at least one coherent light source is received by the at least one holographic waveguide. In operation1004, the light is transmitted from the at least one holographic waveguide to the at least one spatial light modulator. In operation1006, the light is modulated utilizing the at least one spatial light modulator.

In one embodiment, the HMD may further include at least one magnifying lens. In this embodiment, the method1000may include transmitting the modulated light through the at least one magnifying lens. The at least one magnifying lens may include a Fresnel lens or a holographic lens. As an option, the at least one magnifying lens and the at least one holographic waveguide may be directly coupled with no space therebetween.

In another embodiment, the HMD may include at least one polarization element coupled between the at least one magnifying lens and the at least one holographic waveguide. In this other embodiment, the method1000may include polarizing the light or the modulated light utilizing the at least one polarization element, where the polarized modulated light is transmitted through the at least one magnifying lens. Of course, in other embodiments the HMD may not include a polarization element such that the light may not be polarized.

In yet another embodiment, the HMD may include at least one quarter-wave element coupled between the at least one holographic waveguide and the at least one spatial light modulator. With respect to this yet another embodiment, the method1000may include modifying the light from the at least one holographic waveguide, utilizing the at least one quarter-wave element, wherein the modified light is received by the at least one spatial light modulator.

In still yet another embodiment, the HMD may not include a beam splitter. In yet even a further embodiment, the HMD may include a receiver. In this further embodiment, the method1000may include receiving, by the receiver, pixel data from a remote source over a network, for display via the HMD. The HMD may perform the method1000to output the pixel data as a VR image or video for viewing by the user. The remote source may be the exemplary computing system described below with respect toFIG.11.

FIG.11illustrates an exemplary computing system1100, in accordance with an embodiment. The HMD of the method1000ofFIG.10(not shown), or the VR display100ofFIG.1or of any other embodiment described above (also not shown), may be in communication with the system1100to receive output of the system1100and to provide input to the system1100. Just by way of example, the HMD/VR display may receive from the system1100virtual images in the form of pixel data. The HMD/VR display and the system1100may be located in the same environment, or remotely (e.g. the system1100may be located in the cloud). It should be noted that the HMD/VR display may communicate with the system1100via a wired connection or a wireless network connection (e.g. WiFi, cellular network etc.). As an option, one or more of the components shown in system1100may be implemented within the HMD/VR display.

As shown, the system1100includes at least one central processor1101which is connected to a communication bus1102. The system1100also includes main memory1104[e.g. random access memory (RAM), etc.]. The system1100also includes a graphics processor1106and a display1108.

The system1100may also include a secondary storage1110. The secondary storage1110includes, for example, a hard disk drive and/or a removable storage drive, representing a floppy disk drive, a magnetic tape drive, a compact disk drive, a flash drive or other flash storage, etc. The removable storage drive reads from and/or writes to a removable storage unit in a well-known manner.

Computer programs, or computer control logic algorithms, may be stored in the main memory1104, the secondary storage1110, and/or any other memory, for that matter. Such computer programs, when executed, enable the system1100to perform various functions, including for example calibration of the HMD102, forming of live video, and coloring of pixels on display104, as set forth above. The computer programs, when executed, may also enable integration of live video with a virtual environment to provide a modified virtual reality, a mixed reality, or an augmented reality to the user. Memory1104, storage1110and/or any other storage are possible examples of non-transitory computer-readable media.

The system1100may also include one or more communication modules1112. The communication module1112may be operable to facilitate communication between the system1100and one or more networks, and/or with one or more devices (e.g. game consoles, personal computers, servers etc.) through a variety of possible standard or proprietary wired or wireless communication protocols (e.g. via Bluetooth, Near Field Communication (NFC), Cellular communication, etc.).

As also shown, the system1100may include one or more input devices1114. The input devices1114may be a wired or wireless input device. In various embodiments, each input device1114may include a keyboard, touch pad, touch screen, game controller, remote controller, or any other device capable of being used by a user to provide input to the system1100.