Abstract: A display device may include first and second display modules that provide image light to first and second waveguides. The waveguides may direct the image light to first and second eye boxes. Each display module may include optics mounted to a housing and mechanical alignment structures that mechanically adjust the position of an optical axis of the optics. The alignment structures may rotate the entire housing, may mechanically translate the optics, may adjust the position of a spatial light modulator within the module, and/or control circuitry may change a subset of pixels used by the modulator to compensate for optical misalignment between the first and second eye boxes. The device may include optical misalignment sensors that detect the optical misalignment. The control circuitry may compensate for the optical misalignment as detected by the optical misalignment sensors.

Abstract: An electronic device may include a display panel configured to produce light and a lens assembly that receives the light from the display panel. The lens assembly may include a first lens and a second lens. The second lens may be a removable lens that is configured to be selectively attached to the lens assembly. The lens assembly may also include a partially reflective mirror that is interposed between the first lens and the display panel, a reflective polarizer that is interposed between the first lens and the second lens when the second lens is attached to the lens assembly, and a quarter wave plate that is interposed between the reflective polarizer and the second lens when the second lens element is attached to the lens assembly.

Abstract: A display may include a waveguide for providing light to an eye box. The display may include polarization recycling structures having a polarizing beam splitter and a prism. The polarizing beam splitter may transmit a first portion of unpolarized light as first image light having a first polarization and may reflect a second portion of the unpolarized light as second image light having a second polarization. One or more waveplates may be mounted to the prism for transmitting the second image light. Upon transmission by the waveplate(s), the second image light may have the same polarization as the first image light. An input coupler may couple the first and second image light into the waveguide. Providing polarized light to the waveguide may maximize the optical efficiency of the waveguide. The polarization recycling structures may maximize the amount of the image light that is coupled into the waveguide.

Abstract: An electronic device may include a waveguide with an input coupler and an output coupler. The input coupler may receive the image light from imaging optics. The input coupler may be an input coupling prism and the imaging optics may include lens elements. World light may be viewable at an eye box through the output coupler. Biasing, compensation, and/or prescription lenses may overlap the output coupler. The input coupling prism, the lens elements in the imaging optics, and/or one or more of the biasing, compensation, and prescription lenses may be formed from gradient index (GRIN) material. The GRIN material may have a gradient refractive index that varies in one or more gradient directions. Use of GRIN materials may minimize the volume required to form the device without sacrificing optical performance. In addition, the GRIN materials may compensate for dispersion and aberrations in the device.

Abstract: A display may include illumination optics, a spatial modulator, and a waveguide. The illumination optics may produce illumination that is modulated by the spatial modulator to produce image light. The waveguide may direct the image light towards an eye box. The illumination optics may include light source sets that produce the illumination. Each set may include a low power light source and a high power light source. In a first state, the high and low power light sources may be active. In a second state, the low power light sources may be active. Control circuitry may adjust between the first and second states based on image data. The second state may be used when virtual objects in the image data are confined to a peripheral region of the field of view of the eye box.

Abstract: An electronic device may include a display module that generates light and an optical system that redirects the light towards an eye box. The system may include an input coupler on a waveguide and a lens that directs the light towards the input coupler. The input coupler may include a prism having a reflective surface that reflects the light into the waveguide. The reflective surface may be curved to provide the light with an optical power. The prism may be configured to expand a field of view of the light. A birefringent beam displacer may expand the effective pupil size of the light. The lens may include lens elements that converge the light at a location between the lens elements and the waveguide. A switchable panel may be placed at the location and toggled between first and second orientations to increase the effective resolution of the light.

Abstract: A display system may include a waveguide and an input coupling prism. The waveguide may have a lateral surface with a deformed region. The prism may couple the light into the waveguide at an angle whereby the light first reflects off the deformed region. The display module may include a display panel that provides the light with planar wavefronts. The display module may include a deformation mitigation structure that distorts the planar wavefronts to produce non-planar wavefronts. The shape of the non-planar wavefronts may be selected to reverse distortion to the wavefronts of the light produced by the first reflection of the light off the deformed region of the lateral surface. This may serve to mitigate distortion in the light produced by the deformed region of the lateral surface and may serve to maximize the sharpness images in the image light provided to an eye box.

Abstract: An electronic device may include an emissive display panel that emits light. The light may propagate along an optical path extending to an eye box. A waveguide with an input coupler and an output coupler may be interposed on the optical path. An angle-selective transmission filter (ASTF) may be interposed on the optical path and may filter the emitted light as a function of angle to remove high-angle light from the optical path before the light is provided to the output coupler. The ASTF may include diffractive grating structures such as thin-film holograms, volume holograms, or surface relief gratings, louvered mirrors, multi-layer coatings, or a pinhole array. This ASTF may serve to minimize stray light within the display, thereby optimizing the contrast and the modulation transfer function (MTF) of the display.

Abstract: An electronic device may include an optical combiner with a waveguide. The waveguide may have an output coupler that directs high resolution light towards an eye box within a field of view. Peripheral light sources may provide low resolution peripheral light to the eye box about a periphery of the field of view. The peripheral light sources may be mounted to a frame for the waveguide, to an additional substrate mounted to the frame and overlapping the waveguide, in a low resolution projector that projects the peripheral light towards reflective structures in the additional substrate, or in a display module that produces the high resolution light. The optical combiner may overlay real world light with the high resolution light and the low resolution peripheral light.

Abstract: A display device may include first and second display modules that provide image light to first and second waveguides. The waveguides may direct the image light to first and second eye boxes. Each display module may include optics mounted to a housing and mechanical alignment structures that mechanically adjust the position of an optical axis of the optics. The alignment structures may rotate the entire housing, may mechanically translate the optics, may adjust the position of a spatial light modulator within the module, and/or control circuitry may change a subset of pixels used by the modulator to compensate for optical misalignment between the first and second eye boxes. The device may include optical misalignment sensors that detect the optical misalignment. The control circuitry may compensate for the optical misalignment as detected by the optical misalignment sensors.

Abstract: An electronic device may have a spatial light modulator. Control circuitry in the electronic device may use the spatial light modulator to generate images. A light source may be used to produce illumination for the spatial light modulator. An optical system may direct the illumination onto the spatial light modulator and may direct corresponding reflected image light towards eye boxes for viewing by a user. Head-mounted support structures may be used to support the spatial light modulator, light source, and optical system. The light source may include light-emitting elements such as light-emitting diodes or lasers. Multiple light-emitting elements may be provided in the light source in a one-dimensional or two-dimensional array. During operation, the control circuitry can individually adjust the light-emitting elements.

Abstract: A display having a reflective display panel may provide image light to an eye box. The panel may include mirrors rotatable between first and second angles. The mirrors may take a non-zero time period to transition between the first and second angles. During the non-zero time period, the light source may emit pulses of illumination. The mirrors may reflect the pulses of illumination as offset pupils of image light. The mirrors may be at respective intermediate angles while reflecting each of the pulses of illumination. The mirrors may toggle between the first and second angles at a sufficiently fast rate such that the offset pupils form an effective pupil that is expanded in at least one dimension. If desired, the offset pupils may be used to display virtual objects in different focal planes at the eye box.

Abstract: An electronic device may include a display system for presenting images close to a user's eyes. The display system may include a display unit that directs light and an optical system that redirects the light from the display unit towards a user's eyes. The optical system may include an input coupler and an output coupler formed on a waveguide. The input coupler may redirect light from the display unit so that it propagates in the waveguide towards the output coupler. The output coupler may redirect the light from the input coupler so that it exits the waveguide towards the user's eyes. A light-redirecting element may be used to redirect edge light that would otherwise be outside of the user's field of view towards the user's eyes.

Abstract: An electronic device may include a display module that generates light and an optical system that redirects the light towards an eye box. The system may include an input coupler on a waveguide and a lens that directs the light towards the input coupler. The input coupler may include a prism having a reflective surface that reflects the light into the waveguide. The reflective surface may be curved to provide the light with an optical power. The prism may be configured to expand a field of view of the light. A birefringent beam displacer may expand the effective pupil size of the light. The lens may include lens elements that converge the light at a location between the lens elements and the waveguide. A switchable panel may be placed at the location and toggled between first and second orientations to increase the effective resolution of the light.

Abstract: An electronic device may provide foveated images at an eye box. The device may have a first display module that produces a low resolution portion of the image and a second display module that produces a high resolution portion of the image. A reflective input coupling prism may be mounted to a waveguide. A steering mirror may overlap the prism. The mirror may receive the high resolution portion through the waveguide and the prism. The mirror may reflect the high resolution portion back into the waveguide and may be adjusted to shift a location of the high resolution portion within the image. For example, the steering mirror may adjust the position of the high resolution portion to align with the gaze direction at the eye box. A reflective surface of the prism may reflect the low resolution portion of the image into the waveguide.

Abstract: An electronic device may include a display system for presenting images close to a user's eyes. The display system may include a display unit that directs light and an optical system that redirects the light from the display unit towards a user's eyes. The optical system may include an input coupler and an output coupler formed on a waveguide. The input coupler may redirect light from the display unit so that it propagates in the waveguide towards the output coupler. The output coupler may redirect the light from the input coupler so that it exits the waveguide towards the user's eyes. A light-redirecting element may be used to redirect edge light that would otherwise be outside of the user's field of view towards the user's eyes.

Abstract: An electronic device may have a display system with a module that produces image light and a waveguide that directs the image light towards an eye box. The module may include a light source, spatial light modulator, and collimating lens between the lens and modulator. The lens may direct illumination from the light source to the modulator, which modulates the illumination to produce the image light. The lens may have a geometry that illuminates the modulator with a non-uniform illumination pattern to mitigate subsequent brightness non-uniformity introduced by the waveguide. The light source may include one or more LEDs that are independently driven by control circuitry over one or more drive lines to help mitigate the non-uniformity introduced by the waveguide and/or to operate the display in a heads-up display mode.

Abstract: A display system may include a waveguide, an input coupler with a first surface relief grating (SRG), and an output coupler with a second SRG. A display module may produce image light that is coupled into the waveguide by the first SRG. The first SRG may have an input vector non-parallel with respect to a normal axis of the waveguide. The display module may have an optical axis tilted with respect to the input vector by a non-zero angle. A prism may redirect the image light from the module to the first SRG in a direction parallel to the input vector. The module may include lens elements with an optical axis offset with respect to the center of the field of the image light. This may cause the lens elements to output the image light in a direction parallel to the input vector of the first SRG.

Abstract: An electronic device may include a display module that generates light and an optical system that redirects the light towards an eye box. The system may include an input coupler on a waveguide and a lens that directs the light towards the input coupler. The input coupler may include a prism having a reflective surface that reflects the light into the waveguide. The reflective surface may be curved to provide the light with an optical power. The prism may be configured to expand a field of view of the light. A birefringent beam displacer may expand the effective pupil size of the light. The lens may include lens elements that converge the light at a location between the lens elements and the waveguide. A switchable panel may be placed at the location and toggled between first and second orientations to increase the effective resolution of the light.

Abstract: A display may include illumination optics (36), a spatial modulator (40) and a waveguide (26). The illumination optics may produce illumination that is modulated by the spatial modulator to produce image light. The waveguide may direct the image light towards an eye box. The illumination optics may include light sources (58) an X-plate (44), and at least one Fresnel lens (60) interposed between the light sources and the X-plate. The Fresnel lenses may minimize the size of the illumination optics while still exhibiting satisfactory optical performance. The spatial light modulator may include a reflective display panel (50) and a powered prism (48) with a reflective coating on a curved reflective surface. The powered prism may optimize f-number while minimizing the volume of the spatial light modulator. The collimating optics may include a diffractive optical element (56) that compensates for thermal effects and chromatic dispersion in the display.