A pupil-replicating lightguide includes a slab of transparent material, a switchable out-coupling grating for out-coupling portions of image light to propagate towards an eyebox, and a switchable tracking grating for redirecting tracking light carrying an eye image towards an eye tracking camera. One of the two gratings may be turned ON while the other is turned OFF, in a time-sequential manner, allowing the combined use of the pupil-replicating lightguide for carrying image light and eye tracking light.

An illuminator for a display panel includes a slab of transparent material for propagating illuminating light between outer surfaces of the slab, an out-coupler supported by the slab for out-coupling portions of the illuminating light along one of the outer surfaces of the slab, and a tunable microlens array for forming an array of light spots from the out-coupled illuminating light portions downstream of the focusing element for illuminating pixels of the display panel. The array of light spots may be repeated at a distance from the tunable microlens array due to Talbot effect. The display panel may be illuminated in a color-sequential manner, and the tunable microlens array may be used to adjust the focal plane position for each color channel individually.

A pupil-replicating lightguide includes a slab of transparent material for guiding image light in the slab, and an out-coupling structure supported by the slab for out-coupling portions of the image light from the slab. The portions are laterally offset from one another along a path of the image light in the slab. The out-coupling grating structure has a switchable distribution of out-coupling efficiency for redirecting the portions of out-coupled light to a desired location such as a current location of an eye of the viewer determined by an eye tracking system. The out-coupling grating structure may include a plurality of diffraction gratings having different local slant angles of grating fringes.

A field of view of an imaging or ranging device may be increased multiple times by providing a switchable diffraction grating structure upstream of an imaging camera or ranging light source. The switchable diffraction grating changes the angle of propagating of incoming light by a fixed step, enabling the device to switch between several portions of a compound field of view. The switchable diffraction grating structure may be supported by a lightguide that guides the image light or ranging light by a series of reflections from opposed surfaces of the lightguide.

An optical device includes a first polarization selective reflector; a second polarization selective reflector positioned relative to the first polarization selective reflector so that the first polarization selective reflector directs first light having a first nonplanar polarization toward the second polarization selective reflector and the second polarization selective reflector directs at least a portion of the first light toward the first polarization selective reflector as second light. The optical device includes a first reflector positioned relative to the first polarization selective reflector so that the first polarization selective reflector directs at least a portion of the second light having a second nonplanar polarization toward the first reflector as third light.

A device includes a display configured to generate an image light. The device also includes a waveguide optically coupled with the display and configured to guide the image light to an exit pupil of the device. The waveguide includes a grating including a birefringent material, and a birefringence of the grating is configured to increase along a pupil-expanding direction of the device.

A three-dimensional light modulator, of which the pixels are combined to form modulation elements. Each modulation element can be coded with a preset discrete value such that three-dimensionally arranged object points can be holographically reconstructed. The light modulator is characterized in that assigned to the pixels of the modulator are beam splitters or beam combiners which, for each modulation element, combine the light wave parts modulated by the pixels by means of refraction or diffraction on the output side to form a common light beam which exits the modulation element in a set propagation direction.

An electronic device may have a reflective display with a pixel array that generates images. The reflective display may be illuminated by an illumination system. Light from the illumination system may be reflected by the pixel array as image light. The image light may be provided to a viewer using a waveguide with diffractive input and output couplers. The illumination system may have a waveguide. The illumination system may also have a light source such as one or more light-emitting diodes. Light from the light source may be coupled into the waveguide of the illumination system by a diffractive coupler such as volume hologram that serves as an input coupler. Light from the light source may be routed to the display to illuminate the display using the waveguide in the illumination system and a diffractive coupler such as a volume hologram that serves as an output coupler.

The apertures typically used for hologram recording create unwanted secondary holograms by diffracting light. Aperture-free hologram recording eliminates these unwanted secondary holograms. Aperture-free hologram recording includes applying a mask to the holographic recording medium. The mask controls the size of the recorded hologram like an aperture but does not create unwanted secondary holograms. Hologram fringes are only present in the desired recording area and a thin boundary region. The mask may be present during recording, or the mask may be used to pre-bleach the holographic recording medium. Pre-bleaching the holographic recording medium renders a portion of the holographic recording medium insensitive to light, the hologram is recorded in the light-sensitive portions of the holographic recording medium.

An image display apparatus according to an embodiment of the present technology includes: a light emission unit; an object to be irradiated; and a reflection portion. The light emission unit emits image light along a predetermined axis. The object to be irradiated is disposed at least partially around the predetermined axis. The reflection portion is disposed facing the light emission unit with reference to the predetermined axis and has a plurality of reflection regions that divides the emitted image light into a plurality of light beams and reflects the light beams toward the object to be irradiated.