Compact optical system for head mounted display systems
Diffractive optical elements integrated with HMD systems enhance the flexibility and performance of VR/AR lenses, improving depth of field and field of view, thereby increasing immersion.
Patent Information
- Application Number
- JP2024542903
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2022-01-21
- Filing Date
- 2022-12-14
- Publication Date
- 2025-01-30
AI Technical Summary
Conventional head-mounted display (HMD) lens systems are often designed specifically for each system, limiting the overall design flexibility and optical interaction between elements, which can hinder the performance and immersion experience in virtual reality (VR) or augmented reality (AR) environments.
The use of diffractive optical elements, such as pancake optical systems, which are reflective and refractive, are integrated with the display system to provide a flexible and compact optical solution that enhances the user's field of view and immersion by adjusting light for each eye separately, utilizing polarization-based optics.
This approach allows for a more adaptable and efficient optical system that improves the depth of field and field of view in VR/AR systems, enhancing the user's perception of three-dimensional images and increasing immersion.
Smart Images
Figure 2025502996000001_ABST
Abstract
Description
[Technical field]
[0001] The present disclosure relates generally to optical systems, and more particularly, to optical systems for use with head mounted display systems. [Background technology]
[0002] Near-eye display technology can be used to present information and images to a user as part of a virtual reality (VR), augmented reality (AR) or mixed reality (MR) system. Such near-eye displays can be incorporated into a head-mounted display (HMD) device or headset. While these near-eye information displays can be oriented as direct-view, the information displays are often combined with one or more lenses in the HMD. A lens system can include a lens, various optical elements, an aperture stop, and a lens housing for storing the various components in optical alignment with one another. While such lenses can enhance the VR or AR experience, the performance of a lens system depends, in part, on the design of each of the elements of the system and the overall design of the system that defines the optical interactions between the elements. [Brief description of the drawings]
[0003] In the drawings, identical reference numbers identify similar elements or acts. The sizes and relative positions of elements in the drawings are not necessarily drawn to scale. For example, the shapes and angles of various elements are not necessarily drawn to scale, and some of these elements may be arbitrarily enlarged and positioned to improve the readability of the drawings. Furthermore, the particular drawn shapes of these elements are not necessarily intended to convey any information regarding the actual shape of those particular elements, but may only be selected for ease of recognition in the drawings.
[0004] [Figure 1] 1 is an illustration of a head mounted display system according to one non-limiting exemplary implementation.
[0005] [Diagram 2] 1 is a simplified cross-sectional view of a portion of an example HMD system positioned relative to a user's eyes, according to one non-limiting illustrated implementation.
[0006] [Diagram 3] 1 is a simplified cross-sectional view of a system including a display system and an optical subsystem, where the optical system includes a diffractive optical element coupled to a surface of the display system, according to one non-limiting illustrative implementation.
[0007] [Figure 4] FIG. 1 is a schematic cross-sectional view of a system comprising a display system and an optical subsystem, according to one non-limiting illustrative implementation, where the optical system comprises a diffractive optical element bonded to a surface of the display system and further comprises a reflective polarizer and a quarter-wave plate.
[0008] [Diagram 5] FIG. 1 is a simplified cross-sectional view of a system comprising a display system and an optical subsystem, according to one non-limiting illustrative implementation, where the optical system comprises a diffractive optical element bonded to a surface of the display system and further comprises a reflective polarizer, a quarter-wave plate, and an optically transparent component positioned between the quarter-wave plate and the diffractive optical element.
[0009] [Figure 6] 1 is a surface phase map showing the phase profile of an example diffractive optical element, according to one non-limiting illustrated implementation.
[0010] [Figure 7] 7 is a cross-sectional plot of the phase of the diffractive optical element of FIG. 6 along the horizontal (x) axis according to one non-limiting illustrative implementation. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0011] In the following description, certain specific details are set forth to provide a thorough understanding of various disclosed implementations. However, those skilled in the art will recognize that implementations may be practiced without one or more of these specific details, or with other methods, components, materials, etc. In other instances, well-known structures associated with computer systems, server computers, and / or communication networks have not been shown or described in detail to avoid unnecessarily obscuring the description of implementations.
[0012] Unless the context requires otherwise, throughout this specification and the claims which follow, the term "comprising" is synonymous with "including" and is inclusive or open-ended (i.e., does not exclude additional unrecited elements or method actions).
[0013] References throughout this specification to "one implementation" or "an implementation" mean that a particular feature, structure, or characteristic described in connection with that implementation is included in at least one implementation. Thus, the appearances of the phrase "in one implementation" or "in an implementation" in various places throughout this specification are not necessarily all referring to the same implementation. Furthermore, particular features, structures, or characteristics may be combined in any suitable manner in one or more implementations.
[0014] As used in this specification and the appended claims, the singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise. It should also be noted that the term "or" is generally utilized in its sense including "and / or" unless the context clearly dictates otherwise.
[0015] The headings and abstract of the disclosure provided herein are for convenience only and do not interpret the scope or meaning of the implementations.
[0016] In various examples described herein, the techniques and architectures may be used to generate images focused at the eye (s) of a user of an HMD device. Examples of HMD devices may include a display device worn on the user's head or as part of a helmet, such as a head mounted display ("HMD") device or headset, and may include position or motion sensors to measure the inertial position or orientation of the HMD device. The display device may include a display in front of one eye, each eye, or both eyes. The display device may include a liquid crystal display (LCD), an organic light emitting diode (OLED), a liquid crystal on silicon (LCoS), or a cathode ray tube (CRT), to name just a few. The HMD device may display computer-generated images, referred to as virtual images. For example, a processor of the HMD device may render and display a synthetic (virtual) scene, such that a viewer (the wearer of the HMD device) perceives the scene as real (or augmented reality), as described below.
[0017] In some examples, an LCD display device comprises several components: a display matrix, which intercepts light in a granular or pixelated manner to generate an image, and a light source or backlight. The light source is typically located behind the display matrix and illuminates the image. For color displays, the backlight typically emits a broad spectrum of light, e.g., white light.
[0018] Near-eye display technology may be used to present information and images to a user as part of a virtual reality ("VR") or augmented reality ("AR") system, which may be in the form of an HMD device such as those introduced above. A VR or AR HMD may use one or more lenses to direct light associated with images displayed on one or more information displays (e.g., pixelated LCD display devices) to the user's eyes. Among other examples, lenses are used to bend light from an information display to make the information display appear farther away than it actually is to the user. This provides the user with a greater depth of field in the virtual environment, allowing the user to more easily focus on the displayed image. Lenses may also be used in a VR or AR headset to increase the field of view of the information display to the user. A larger field of view may increase the immersive effect of the VR or AR system. Lenses may also be used in a VR or AR headset to shape the light from a single display so that the light the user receives is separately adjusted for the user's left and right eyes. With a separately adjusted image for each eye, the user may perceive, for example, a stereoscopic or three-dimensional image. The lenses are further designed in a near-eye environment, with the constraint that the user's eyes are relatively close to the information display.
[0019] In at least some implementations of the present disclosure, traditional HMD lenses may be replaced with one or more diffractive optical elements coupled to or located adjacent to the display system, where the diffractive optical element or elements are part of a catadioptric optical system, also referred to as a "pancake" optical system or a "folded" optical system, where light is both reflected and refracted. As described further below, examples of catadioptric optical systems of the present disclosure are based on polarization.
[0020] FIG. 1 is a schematic diagram illustrating a wearable HMD device 100 that is wearable on a user's head. A computing device associated with the HMD device 100 may provide rendering data associated with individual virtual content items to the HMD device 100 to cause the individual virtual content items to be presented on a display associated with the HMD device 100, such as displays 110a and 110b shown within dotted lines in FIG. 1. The rendering data may include instructions for rendering a graphical representation of the virtual content items via the device's display. For example, the rendering data may include instructions describing geometry, perspective, textures, lighting, shading, etc. associated with the virtual content items. In an illustrative example, the virtual content items may be presented on the display of the HMD device 100 as part of a game that a user may play using the HMD device 100.
[0021] In some examples, the computing device may be located remotely from the HMD device 100 in a network such as the Internet. In other embodiments, the computing device may be collocated with the HMD device 100 (e.g., incorporated into the HMD device 100 and coupled to the HMD device via a wired or wireless connection). Additionally, the HMD device 100 may be communicatively coupled to a network in any manner, such as a global or local wired or wireless connection (e.g., a local area network (LAN), an intranet, Bluetooth, etc.). The network may facilitate communication between the computing device and the HMD device 100 associated with one or more users.
[0022] In the illustrated embodiment, the HMD device 100 includes a set of straps 102 attached to a body 108. The set of straps 102 can be used to selectively and securely mount the HMD device 100 on a user's head to view visual content. The body 108 can include a control panel 104 for controlling various aspects of the HMD device 100. Non-limiting examples of electrical input devices of the control panel 104 include a keypad having a set of keys for providing alphanumeric input or navigating a menu, or a dial or knob electrically coupled to a controller. The control panel 104 can include a display 106 for displaying information about the HMD device 100. In some embodiments, the display 106 can be a touch screen input device with which a user can interact to control the HMD 100.
[0023] 2 is a simplified cross-sectional view of a portion 202 of an HMD device 200 positioned relative to a user's eye 206. For example, the HMD device 200 may be the same as or similar to the HMD device 100 of FIG. 1. In certain embodiments, the HMD device 200 may be configured to display images seen by both the left and right eyes of a user. This may be accomplished using separate left and right LCD displays, or may be accomplished using a single LCD display. Similarly, the HMD device 200 (e.g., in the form of a VR or AR headset) may include a single lens assembly or optical system, or may use separate left and right lens assemblies or optical systems.
[0024] Example light rays 208 and 210 illustrate possible light paths from the HMD device 200 to the cornea 212 of the user's eye 206. The cornea 212 may be treated as having a substantially spherical shape. The HMD device 200 may include a near-eye display such that the paths of the light rays 208 and 210 are relatively short, such as to provide an eye relief of about 15 millimeters. In this case, the optics of the HMD device 200 are configured to focus light onto a surface (e.g., the cornea 212) that is relatively close to the HMD device. Such a configuration may involve a pancake optical system having a relatively thin profile that allows the pancake optical system to fit within the HMD device 200 while still allowing physical clearance from the user's eye 206.
[0025] 3 is a simplified cross-sectional view of a system 300 including a display and an optical subsystem according to one or more embodiments. The system 300 may be incorporated into a head-mounted device, such as the HMD device 100 or 200. However, it is understood that the system 300 may be incorporated into other types of devices, including, but not limited to, cameras, binoculars, office equipment, scientific instruments, and the like. The system 300 may include a pixelated display device 302, sometimes referred to as an information display or display system, and an optical subsystem 306 that may be incorporated within (e.g., laminated thereon, adhesively secured thereto, located adjacent thereto). A schematic diagram of a user's eye 308 is also illustrated. Such elements are aligned along a horizontal optical axis of the system 300.
[0026] The display system 302 may include a pixelated display 304 and a circular polarizer 305 positioned in front of the pixelated display to provide circularly polarized light (e.g., right-handed, left-handed). In other implementations, the display 304 may be configured to output light of different polarizations, such as vertically or horizontally polarized. In some configurations, the display 304 may be configured to output polarized light of a particular color, such as blue and green light polarized in a first polarization state and red light polarized in a second polarization state. The first polarization state may be orthogonal to the second polarization state (e.g., vertically polarized, horizontally polarized, etc.).
[0027] The display system 302 may include a backlight assembly that emits light, which may include light sources such as one or more light emitting diodes (LEDs), one or more OLEDs, one or more cold cathode fluorescent lamps (CCFLs), one or more lasers, one or more quantum dots, or any combination of these light source examples. The light sources in the backlight assembly may emit light across a broad spectrum (e.g., white light) such that the display system 302 can generate color images across the visible spectrum. The backlight assembly may emit light uniformly across its front surface, for example, over a range of about 160-180 degrees.
[0028] The display system 302, in conjunction with the backlight assembly, may emit light over an angular range of up to about 180 degrees (light nearly parallel to the plane of the backlight assembly). This range of emission angles is sometimes referred to as the field of view of the backlight assembly or the cone of light of the backlight assembly. In some embodiments, the display 304 of the display system 302 may be an LCD matrix including one or more polarizing layers, a liquid crystal layer, and a thin film transistor layer. The LCD matrix creates an image by obscuring portions of the backlight in a pixelated manner. An image is displayed when light is emitted from the backlight assembly and passes through the display 304 (e.g., an LCD matrix) and a circular polarizer 305 (or other polarizer, if present). The backlight assembly and the display may be separated from each other, or these two components may be sandwiched together with little, if any, space between them.
[0029] The optical subsystem 306 may include one or more diffractive optical elements for directing the light 320, 322 from the display 302 toward the user's eye 308. The optical subsystem 306 may have a catadioptric or pancake configuration, where the light is reflected and refracted or "bent", for example, to provide a very compact design. The optical subsystem 306 may include one or more of a reflective polarizer, a wave plate (e.g., a quarter wave plate), additional diffractive optical elements, etc. In this case, the optical subsystem 306 may include an assembly of optical elements configured to direct the light from the display system 302 toward the user's eye 308 using on-axis optical bending based at least in part on the polarization of the light, as described further below. In some embodiments, the optical system 306 may include multiple stacked diffractive optical elements, each tuned to operate on a particular polarization of light and to pass light of a different polarization state (e.g., orthogonal). The optical subsystem 306 may be affixed (eg, adhesively bonded or laminated using an optically clear adhesive such as a pressure sensitive adhesive or PSA) to the remainder of the display system 302.
[0030] As described further below, the optical subsystem 306 may include various other optical elements. For example, the optical subsystem 306 may include at least one polarizing beam splitter, also referred to herein as a reflective polarizer. In at least some implementations, the reflective polarizer 338 may be adhesively bonded to an optically transparent substrate (e.g., via a suitable optically transparent adhesive such as PSA). The reflective polarizer may be located between the diffractive optical element and the exit surface (or side) of the optical subsystem. The reflective polarizer may substantially transmit light having a first polarization state and substantially reflect light having a second polarization state orthogonal to the first polarization state. In at least some implementations, the reflective polarizer may represent a beam splitter that passes only linearly polarized light in a first orientation (e.g., horizontal), thereby reflecting all other light that is not linearly polarized in the first orientation. The reflective polarizer may be considered a linear polarizer reflector or a reflective linear polarizer. That is, in at least some implementations, the reflective polarizer may combine the functions of a linear polarizer and a beam splitter into a single element.
[0031] 4 is a simplified cross-sectional view of a system 400 including a display and an optical subsystem, according to one or more embodiments. The system 400 may be incorporated into a head-mounted device, such as the HMD device 100 or 200. However, it is understood that the system 400 may be incorporated into other types of devices, including, but not limited to, cameras, binoculars, office equipment, scientific instruments, and the like. Many of the components or features of the system 400 may be similar or identical to components of other systems described herein. Thus, descriptions of such other systems may also apply to the system 400. Furthermore, one or more features or components of the system 400 may be combined with one or more features or components of other systems described herein, and vice versa, such that any combination of the systems of the present disclosure may be used to implement the techniques described herein.
[0032] System 400 may include a pixelated display device or system 402, sometimes referred to as an information display or display system, and optical subsystems 406 and 410, which may be considered part of the display system or separate components of system 400. A schematic diagram of a user's eye 408 is also illustrated. Such elements are aligned along a horizontal optical axis.
[0033] The display system 402 may include a pixelated display 404 and a polarizer 405 (e.g., a circular polarizer) positioned in front of the pixelated display to provide circularly polarized light. The display system 402 may include a backlight assembly that emits light, which may include light sources such as one or more light emitting diodes (LEDs), one or more OLEDs, one or more cold cathode fluorescent lamps (CCFLs), one or more lasers, one or more quantum dots, or any combination of these light source examples. The light sources in the backlight assembly may emit light across a broad spectrum (e.g., white light) such that the display system 402 can generate color images across the visible spectrum. The backlight assembly may emit light uniformly across its front surface, for example, over a range of about 160-180 degrees.
[0034] The display system 402, in conjunction with the backlight assembly, may emit light over an angular range of up to about 180 degrees (light nearly parallel to the plane of the backlight assembly). This range of emission angles is sometimes referred to as the field of view of the backlight assembly or the cone of light of the backlight assembly. In some embodiments, the display 404 of the display system 402 may be an LCD matrix including one or more polarizing layers, liquid crystal layers, and thin film transistor layers. The LCD matrix creates an image by obscuring portions of the backlight in a pixelated manner. An image is displayed when light is emitted from the backlight assembly and passes through the display 404 (e.g., an LCD matrix) and a circular polarizer 405. The backlight assembly and the display may be separated from each other, or these two components may be sandwiched together with little, if any, space between them.
[0035] The optical subsystems 406 and 410 may include one or more diffractive optical elements 406 located on the display system (e.g., above the polarizer 405) to direct light 420, 422, 424 from the display system 402 toward the user's eye 408. The optical subsystem may have a pancake configuration as described above. The optical subsystem may further include a quarter wave plate 412 and a reflective polarizer 414. In this case, the optical subsystem may include an assembly of optical elements configured to direct light from the display system 402 toward the user's eye 408 using on-axis optical bending based at least in part on the polarization of the light, as described further below. In some embodiments, the diffractive optical element 406 of the optical system includes a first diffractive optical element and a second diffractive optical element stacked together. The components may be attached to each other (e.g., adhesively bonded or laminated using an optically clear adhesive) or may be isolated from each other.
[0036] In at least some implementations, the reflective polarizer 414 may be adhesively bonded to an optically transparent substrate (e.g., via a suitable optically transparent adhesive), and the quarter-wave plate 412 may be bonded to the reflective polarizer. The reflective polarizer 414 may substantially transmit light having a first polarization state and substantially reflect light having a second polarization state orthogonal to the first polarization state. In at least some implementations, the reflective polarizer 414 may represent a beam splitter that passes only linearly polarized light in a first orientation (e.g., horizontal), thereby reflecting all other light that is not linearly polarized in the first orientation. The reflective polarizer 414 may be considered a linear polarizer reflector or a reflective linear polarizer. That is, in at least some implementations, the reflective polarizer 414 may combine the functions of a linear polarizer and a beam splitter into a single element.
[0037] 4 shows folded optical paths 420, 422, 424 of an optical system according to one or more embodiments. In some embodiments, one or more of the optical elements may have one or more coatings or layers, such as anti-reflective coatings, contrast enhancing coatings, reflective or partially reflective coatings, as described above. For example, there may be a partial reflector between the diffractive optical element 406 and the circular polarizer 405 to provide a catadioptric optical system, as described elsewhere herein.
[0038] 5 is a simplified cross-sectional view of a system 500 including a display and an optical subsystem, according to one or more embodiments. The system 500 may be incorporated into a head-mounted device, such as the HMD device 100 or 200. However, it is understood that the system 500 may be incorporated into other types of devices, including, but not limited to, cameras, binoculars, office equipment, scientific instruments, and the like. Many of the components or features of the system 500 may be similar or identical to components of other systems described herein. Thus, descriptions of such other systems may also apply to the system 500. Furthermore, one or more features or components of the system 500 may be combined with one or more features or components of other systems described herein, and vice versa, such that any combination of the systems of the present disclosure may be used to implement the techniques described herein.
[0039] System 500 may be substantially similar to system 400 described above, but may also include an optically transparent layer 502 coupled (e.g., adhesively bonded) between diffractive optical element 406 and quarter wave plate 412. Optically transparent layer or component 502 may be formed from glass, plastic, or any other suitable material.
[0040] Figure 6 is a surface phase map 600 showing the phase profile of an example diffractive optical element having a width and height of 46 millimeters, according to one non-limiting example implementation. The phase is displayed modulo 2π. Figure 7 is a plot 700 showing a cross-section of the phase of the diffractive optical element of Figure 6 along the horizontal (x) axis extending between -5.0 mm and +5.0 mm, according to one non-limiting example implementation.
[0041] The diffractive optical elements described herein may include one or more of any type of diffractive optical element, including, but not limited to, a multi-twist retarder, a wave plate (e.g., a quarter wave plate, a half wave plate), a surface relief, a metalens, an achromatic diffractive lens (ADL), a polarization-based diffractive optical element, and the like.
[0042] As further described above, the diffractive optical element may include a first diffractive optical element and a second diffractive optical element, the first diffractive optical element operable to diffract light of a first polarization state and pass light of a second polarization state, and the second diffractive optical element operable to diffract light of the second polarization state and pass light of the first polarization state. In at least some implementations, the first diffractive optical element is optimized to diffract a first color of light (e.g., red light) having a first polarization state, and the second diffractive optical element is optimized to diffract a second color and a third color of light (e.g., blue and green) having a second polarization state orthogonal to the first polarization state. Thus, multiple (e.g., two) diffractive optical elements may be used to provide optimized diffraction for a particular color based on polarization, such that the overall chromatic aberration of the optical system is significantly reduced.
[0043] In at least some implementations, the display system provides light to an optical system, where the light includes light of a first color that is in one of a first polarization state and a second polarization state, and light of a second color and a third color that is in the other of the first polarization state and the second polarization state.
[0044] The various embodiments described above may be combined to provide further embodiments. All U.S. patents, U.S. patent application publications, U.S. patent applications, foreign patents, foreign patent applications, and non-patent documents mentioned herein and / or listed in the Application Data Sheet are incorporated herein by reference in their entirety. Aspects of the embodiments may be modified, if necessary, to provide further embodiments using concepts from these various patents, applications, and publications.
[0045] These and other changes can be made to the embodiments in light of the above detailed description. In general, in the following claims, the terms used should not be construed to limit the scope of the claims to the specific embodiments disclosed in the specification and claims, but should be construed to include all possible embodiments along with the full scope of equivalents to which such claims are entitled. Thus, the claims are not limited by this disclosure.
Claims
1. 1. A head mounted display system operable to present images to the eyes of a user, comprising: a support structure configured to be worn on a head of the user; A display system supported by the support structure; and a diffractive optical element located on the display system on a surface that faces the user's eye during operation, the diffractive optical element configured to focus light from the display system to the user's eye; An optical system having a catadioptric optical system including: A head mounted display system comprising:
2. The head mounted display system of claim 1 , wherein the diffractive optical element comprises a surface relief or a polarization based diffractive optical element.
3. The head mounted display system of claim 1 , wherein the optical system includes a reflective polarizer positioned between the diffractive optical element and the user's eyes.
4. The head mounted display system of claim 1 , wherein the diffractive optical element comprises an achromatic diffractive lens (ADL).
5. The head mounted display system of claim 1 , wherein the display system includes a backlight including a coherent light source.
6. The head mounted display system of claim 1 , wherein the diffractive optical element comprises a metalens.
7. The head mounted display system of claim 1 , wherein the optical system includes a film laminated to the display system.
8. The head mounted display system of claim 1 , wherein the optical system includes a substrate coupled to the display system.
9. 2. The head mounted display system of claim 1, wherein the diffractive optical element includes a first diffractive optical element and a second diffractive optical element, the first diffractive optical element diffracting light of a first polarization state and passing light of a second polarization state, and the second diffractive optical element diffracting light of the second polarization state and passing light of the first polarization state.
10. 10. The head mounted display system of claim 9, wherein the first diffractive optical element is optimized to diffract light of a first color and the second diffractive optical element is optimized to diffract light of a second color and a third color.
11. The head mounted display system of claim 10 , wherein the first color is red, the second color is blue, and the third color is green.
12. 10. The head mounted display system of claim 9, wherein the display system provides light to the optical system, the light including a first color of light in one of the first polarization state and the second polarization state, and a second color and a third color of light in the other of the first polarization state and the second polarization state.
13. 2. The head mounted display system of claim 1, wherein the optical system further includes a reflective polarizer positioned between the diffractive optical element and the user's eye during operation, and a quarter wave plate positioned between the diffractive optical element and the reflective polarizer.
14. The head mounted display system of claim 13 , further comprising an optically transparent substrate positioned between the diffractive optical element and the quarter wave plate.
15. The head mounted display system of claim 14 , wherein the optically transparent substrate comprises plastic or glass.
16. a display subsystem including an array of pixels; and an optical system having a catadioptric optical system including a diffractive optical element positioned on the display subsystem on a surface that faces an eye of a user during operation, the diffractive optical element configured to focus light from the display subsystem to the eye of the user; A near-eye display system comprising:
17. The near-eye display system of claim 16 , wherein the diffractive optical element comprises a surface relief or a polarization based diffractive optical element.
18. The near-eye display system of claim 16 , wherein the optical system includes a reflective polarizer positioned between the diffractive optical element and the user's eye.
19. The near-eye display system of claim 16 , wherein the diffractive optical element comprises an achromatic diffractive lens (ADL).
20. The near-eye display system of claim 16 , wherein the near-eye display system comprises a backlight including a coherent light source.
21. 20. The near-eye display system of claim 16, wherein the diffractive optical element comprises a metalens.
22. The near-eye display system of claim 16 , wherein the optical system includes a film laminated to the display subsystem.
23. The near-eye display system of claim 16 , wherein the optical system includes a substrate coupled to the display subsystem.
24. 17. The near-eye display system of claim 16, wherein the diffractive optical element includes a first diffractive optical element and a second diffractive optical element, the first diffractive optical element diffracting light of a first polarization state and passing light of a second polarization state, and the second diffractive optical element diffracting light of the second polarization state and passing light of the first polarization state.
25. 25. The near-eye display system of claim 24, wherein the first diffractive optical element is optimized to diffract light of a first color and the second diffractive optical element is optimized to diffract light of a second color and a third color.
26. 26. The near-eye display system of claim 25, wherein the first color is red, the second color is blue, and the third color is green.
27. 25. The near-eye display system of claim 24, wherein the display subsystem provides light to the optical system, the light including light of a first color being one of the first polarization state and the second polarization state, and light of a second color and a third color being the other of the first polarization state and the second polarization state.
28. 17. The near-eye display system of claim 16, wherein the optical system further includes a reflective polarizer positioned between the diffractive optical element and the user's eye during operation, and a quarter-wave plate positioned between the diffractive optical element and the reflective polarizer.
29. 30. The near-eye display system of claim 28, further comprising an optically transparent substrate positioned between the diffractive optical element and the quarter wave plate.
30. 30. The near-eye display system of claim 29, wherein the optically transparent substrate comprises plastic or glass.
31. 1. A head mounted display system operable to present images to the eyes of a user, comprising: a support structure configured to be worn on a head of the user; A display system supported by the support structure; and a diffractive optical element located on the display system on a surface that faces the user's eye during operation, the diffractive optical element configured to focus light from the display system to the user's eye; a reflective polarizer positioned between the diffractive optical element and the user's eye; and A quarter wave plate positioned between the diffractive optical element and the reflective polarizer. An optical system having a catadioptric optical system including: A head mounted display system comprising: