There is disclosed herein a display device comprising a picture generating unit, a waveguide pupil expander and a viewer-tracking system. The picture generating unit comprises a first display channel, a second display channel and a controller. The first display channel is arranged to output first spatially-modulated light of a first colour. The first spatially-modulated light corresponds to a first picture. The second display channel is arranged to output second spatially-modulated light of a second colour. The second spatially-modulated light corresponding to a second picture. The controller is arranged to drive the first display channel and second display channel. The waveguide pupil expander comprises a pair of parallel reflective surfaces. The waveguide pupil expander defines an input port and a viewing window. The input port is arranged to receive the first spatially-modulated light and the second spatially-modulated light. The viewing window is an area or volume within which a viewer may view the first picture and the second picture. The pair of parallel reflective surfaces is arranged to guide the first spatially-modulated light and the second spatially-modulated light from the input port to the viewing window by a series of internal reflections. The reflectivity of a first reflective surface of the pair of parallel reflective surfaces is provided by a graded coating. The graded coating is partially transmissive to light of the first colour and light of the second colour. The transmissivity of the graded coating is non-achromatic. The viewer-tracking system is arranged to determine a viewing position within the viewing window. The controller is arranged to maintain as substantially constant the colour balance of the first and second picture as seen from the viewing position based on the viewing position determined by the viewer-tracking system.

A method and apparatus for generating a hologram with a wide viewing angle is disclosed. The method includes generating a elemental complex hologram by applying oblique projection to three-dimensional (3D) information of an object based on a viewing direction, and generating a final hologram by superposing a plurality of elemental complex holograms generated based on different viewing directions.

A display for displaying a wide Field of View (FoV) scene including a holographic image within the scene, including a first Spatial Light Modulator (SLM) and an optical system for producing a first holographic image at a center of a displayed scene, and a second image display for producing at least a first additional image adjacent to the first holographic image. In some embodiments an augmented reality display is used for the displaying of the first holographic image at the center of a field of view and the second image adjacent to the first holographic image. In some embodiments a virtual reality display is used for the displaying of the first holographic image near the center of a field of view and the second image adjacent to the first holographic image. Related apparatus and methods are also described.

Authentication systems, devices, and methods are provided, which may use a scanner configured to capture an image of an authentication pattern in a predetermined target area; and a hologram generator configured to project a holographic target onto free space in the target area. Moreover, there may be provided a controller configured to process the image and output a determination of whether the authentication pattern meets a predetermined criterion.

A head up display (HUD) system includes: one or more light sources and one or more phase modulators configured to generate and output a hologram; and a replicator configured to receive the hologram, to generate N replications of the hologram from the hologram, and to output the N replications of the hologram, where N is an integer greater than or equal to 2.

Relay systems may be incorporated into optical systems to direct light from at least one image source to a viewing volume. Light from a plurality of image sources may be directed by relay systems to a viewing volume. Some light from the plurality of image sources may be occluded by an occlusion system to reduce undesirable artifacts in when the relayed light from the plurality of image sources are observed in the viewing volume.

A holographic optical system and a holographic display method may be efficiently applied when using a spatial light modulator (SLM). A holographic display apparatus includes a spatial light modulator (SLM) configured to reproduce a hologram, and an optical system configured to perform Fourier transform with respect to the hologram of the SLM using a pair of first and second lenses, the first and second lenses being confocal. A Fourier plane which is a display reference image plane is positioned in the same plane space as the second lens.

According to one embodiment, a stereoscopic image display device includes a three-dimensional pixel unit, a backlight, and an arithmetic/control circuit. The three-dimensional pixel unit includes a plurality of pixel cells that are formed of an optical material having electrically changeable optical characteristics, are arranged in a mutually separated manner and in a three-dimensional manner, and are electrically connected with transparent wiring patterns. The backlight is configured to emit illumination light to the three-dimensional pixel unit. The arithmetic/control circuit is configured to control the plurality of pixel cells individually via the wiring patterns on the basis of input three-dimensional image data to cause the three-dimensional pixel unit to function as a transmissive hologram.

A holographic projection system includes a SLM that receives a light beam and generates a modulated beam projected at an eyebox, where: the modulated beam includes multiple versions of a test image; and the test image includes bright objects and transparent regions, which are selected dark areas of interest for measuring luminance. A control module runs a test to characterize contrast in each of multiple virtual image planes including: controlling the SLM to generate the modulated beam; measuring luminance levels of each of the versions of the test image displayed in the virtual image planes; calculating contrast ratios based on the luminance levels of each of the versions of the test image; determining whether the contrast ratios are within predetermined ranges of predetermined contrast ratios; and adjusting operation of the SLM in response to one of the contrast ratios not being within a corresponding one of the predetermined ranges.

The display apparatus of the present disclosure includes an imaging light generating device and an optical system on which imaging light emitted from the imaging light generating device is incident. The optical system includes a first optical unit having positive power, a second optical unit having a positive power and including a first diffraction element, a third optical unit having positive power, and a fourth optical unit having positive power and including a second diffraction element forming an exit pupil, the first optical unit, the second optical unit, the third optical unit, and the fourth optical unit being aligned in order along an optical path of the imaging light. The second diffraction element is constituted of a volume hologram and has, in a cross-sectional view of the volume hologram, interference fringes continuously varying in pitch and inclination thereof from one end toward another end of the second diffraction element.