An illumination device has a coherent light source that emits coherent light beam, and an optical device that diffuses the coherent light beam, wherein the optical device comprises a first diffusion region that diffuses the coherent light beam to illuminate a first area, and a second diffusion region that diffuses the coherent light beam to display predetermined information in a second area.

Systems may reduce or eliminate the visibility of a boundary between the displaying portions of the system and the non-displaying portions of the system. An exemplary system includes a display screen including a plurality of pixels forming a first periodic structure and a frame surrounding at least a portion of the display screen. The frame may include a holographic structure having a second periodic structure. The first pitch of the first periodic structure may be within 0.5 percent to 20 percent of the second pitch of the second periodic structure.

An illumination device for illuminating a spatial light modulator device. Sub-holograms are used for encoding a hologram into the spatial light modulator device. The Illumination device includes at least one light source for emitting light for illuminating the spatial light modulator device and a beam shaping unit. The beam shaping unit provides a flat-top plateau-type distribution of an absolute value of a complex degree of mutual coherence of the light in a plane of the spatial light modulator device to be illuminated. The flat-top plateau-type distribution of the absolute value of the complex degree of mutual coherence has a shape that is at least similar to a shape of the largest sub-hologram used for encoding of object points into the spatial light modulator device.

A holographic display with an illumination device, an enlarging unit and a light modulator. The illumination device includes at least one light source and a light collimation unit, the light collimation unit collimates the light of the at least one light source and generates a light wave field of the light that is emitted by the light source with a specifiable angular spectrum of plane waves, the enlarging unit is disposed downstream of the light collimation unit, seen in the direction of light propagation, where the enlarging unit includes a transmissive volume hologram realising an anamorphic broadening of the light wave field due to a transmissive interaction of the light wave field with the volume hologram, and the light modulator is disposed upstream or downstream of the anamorphic enlarging unit, seen in the direction of light propagation.

There is disclosed a projector arranged to project a light pattern. The projector comprises a spatial light modulator and a light source. The spatial light modulator has an array of pixels arranged to display a phase pattern. The array of pixels may be a substantially planar array of pixels. Each pixel comprises liquid crystals having a director rotatable in a plane of rotation between a first direction and a second direction. The light source is arranged to illuminate the array of pixels with polarised light such that the light is spatially-modulated in accordance with the phase pattern to form the light pattern. It may be said that the light pattern corresponds to the phase pattern. The angle of incidence of the light on the array of pixels is greater than zero and the light is s-polarised. The first direction is parallel to the polarisation direction of the light. The second direction is in the plane of incidence.

A video communication system uses a light field display to present a holographic image of a remote scene (e.g., a hologram of a remote participant). The system may include a local light field display assembly and a controller. The controller generates display instructions based on visual data corresponding to a remote scene received from a remote image capture system (e.g., a remote light field display system). The display instructions cause the local light field display assembly to generate a holographic image of the remote scene.

Methods, apparatus, devices, and systems for displaying three-dimensional objects by individually diffracting different colors of light are provided. In one aspect, an optically diffractive device includes: first and second diffractive components and a color-selective polarizer therebetween. The first diffractive component is configured to diffract a first color of light in a first polarization state incident at a first incident angle with a first diffraction efficiency at a first diffracted angle, and diffract a second color of light in a second polarization state with a diffraction efficiency substantially less than the first diffraction efficiency. The color-selective polarizer is configured to rotate the second polarization state of the second color of light to the first polarization state. The second diffractive component is configured to diffract the second color of light in the first polarization state with a second diffraction efficiency at a second diffracted angle substantially identical to the first diffracted angle.

Methods, apparatus, devices, and systems for displaying three-dimensional objects by individually diffracting different colors of light are provided. In one aspect, a system includes a display having a plurality of display elements and an optical device including at least two beam expanders configured to expand an input light beam in at least two dimensions to generate an output light beam to the display by diffracting the input light beam to adjust a beam size of the input light beam in the at least two dimensions, the input light beam including a plurality of different colors of light.

A beam expanding film includes a first material layer and a photonic crystal layer that expands a width of incident light and emits light having an expanded width. The photonic crystal layer includes a first material layer and a plurality of second material layers buried in the first material layer. A holographic display apparatus includes a backlight unit configured to provide coherent collimated light; a beam expanding film described above and facing the backlight unit; a flat panel arranged between the backlight unit and the beam expanding film to provide a hologram; and a lens configured to focus a holographic image on a space.

A backlight unit may include: a light source providing coherent light; a light guide plate having a light entrance surface on which light from the light source is incident and a light exit surface through which the light is output; a plurality of diffraction gratings (for example, a first input grating, a second input grating, and a third input grating) that are arranged in different regions of the light guide plate to sequentially diffract the light from the light source such that that the beam width of the light may increase as the light propagates in the light guide plate; and a diffraction grating (for example, an output grating) that diffracts and outputs the light having an increased beam width in a direction toward the outside of the light guide plate.