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: 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 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: 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.

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: An electronic device may include a display module that produces foveated images having high and low resolution regions. The module may include a reflective display panel that produces first reflected light during first time periods and second reflected light during second time periods. The first reflected light may reflect off of a beam splitter to form the low resolution region of the foveated image. The second reflected light may be transmitted by the beam splitter, de-magnified by a lens, and redirected by an optical steering element to produce the high resolution region at a desired, adjustable, location in the foveated image. The reflective display panel may be replaced by sets of emissive display panels that concurrently display the high and low resolution regions in the foveated image. The sets of emissive display panels may be replaced by front-lit reflective display panels.

Abstract: The display may include a display module and a waveguide. The module may produce first light of first wavelengths during first time periods and may produce second light of second wavelengths during second time periods interleaved with the first time periods. Diffractive gratings or a dichroic wedge may redirect the first light into the waveguide at a first angle and may redirect the second light into the waveguide at a second angle separated from the first angle by a separation angle. The separation angle may be equal to half the angle subtended by the projection of a pixel in the module. The first and second time periods may alternate faster than the response of the human eye. This may configure the first and second image light to collectively provide images at an eye box with an increased effective resolution without increasing the space or power consumed by the display module.

Abstract: An electronic device such as a head-mounted display may have a display system that produces images. The display system may have one or more pixel arrays (26-1, 26-2) such as liquid-crystal-on-silicon pixel arrays. Images from the display system may be coupled into a waveguide (116) by an input coupler system (114X, 114Y) and may be coupled out of the waveguide in multiple image planes using an output coupler system (120X, 120Y). The input and output coupler systems may include single couplers, stacks of couplers, and tiled arrays of couplers. Multiplexing techniques such as wavelength multiplexing, polarization multiplexing, time-division multiplexing, multiplexing with image light having different ranges of angular orientations, and/or tunable lens techniques may be used to present images to a user in multiple image planes.

Abstract: An electronic device may have a display that emits image light, a waveguide, and an input coupler that couples the image light into the waveguide. Beam splitter structures may be embedded within the waveguide. The beam splitter structures may partially reflect the image light multiple times and may serve to generate replicated beams of light that are coupled out of the waveguide by an output coupler. The beam splitter structures may replicate the beams across two dimensions to provide an eye box with uniform-intensity light from the display across its area. The beam splitter structures may include stacked partially reflective beam splitter layers, sandwiched transparent substrate layers having different indices of refraction, a thick volume hologram interposed between substrate layers, or combinations of these or other structures. The reflectivity of the beam splitter structures may vary discretely or continuously across the lateral area of the waveguide.

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 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: 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 display module that generates light and an optical system that redirects the light towards an eye box. The system may include an input coupler that couples the light into the waveguide. The input coupler may include a prism on the waveguide and a scanning mirror. The scanning mirror may receive the light through the waveguide and the prism and may reflect the light into the waveguide through the prism while being rotated over a set of orientations. The scanning mirror may fill a relatively large field of view eye box with a corresponding image frame despite the limited field of view of the image light produced by the display module. The orientation of the scanning mirror may be adjusted based on gaze tracking data.