A backlight device includes: a light source to emit coherent light; an optical path difference generator on the light source, the optical path difference generator including an incident surface and a plurality of light emitting surfaces, the light emitting surfaces being parallel to the incident surface and having different separation distances from the incident surface; a light condenser on the optical path difference generator; a diffuser on the light condenser; and a collimator on the diffuser.

A system and method includes a display device comprising a spatial light modulator arranged to output spatially modulated light to form an image. The system further includes a waveguide pupil expander configured to receive spatially modulated light from the display device at an input port thereof and to expand the viewing window of the system. The system further comprises a controller. In examples, the controller is configured to control the spatially modulated light output by the display device, such as to control (e.g., turn off) a light source of the display device, in response to a signal indicating detection of the breakage of glass. The signal indicating detection of the breakage of glass may be generated in response to the detection of stray laser light of the holographic system by an eye-tracking system.

A holographic display system for a motor vehicle includes a light source for generating a beam of coherent light and a spatial light modulator (SLM) having a two-dimensional pixel array. The two-dimensional pixel array modulates the beam of coherent light for generating a plurality of subframes, with each subframe being associated with one of a plurality of partial fields of view. The system further includes a scanner for directing the subframes onto associated sections of a display surface. The system further includes a computer having a memory including instructions, such that a processor is programmed to control the two-dimensional pixel array of the SLM for generating the subframes. The processor is further programmed to control the scanner for directing the subframes onto associated sections of the display surface and displaying a reconstructed image within a full field of view, which includes each of the partial fields of view.

A holographic display apparatus includes a backlight unit having a light source configured to emit coherent light, a spatial light modulator configured to diffract incident light from the backlight unit and generate a holographic image, a beam deflector configured to change a traveling direction of the incident light from the backlight unit to change a focal position of the holographic image, an eye-tracking sensor configured to recognize positions of a viewer's eyeballs, and a controller configured to perform, in real time, calibration of the eye-tracking sensor and the beam deflector to focus the holographic image on the recognized positions of the viewer's eyeballs.

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.

A holographic display apparatus including a freeform curved surface and an operating method of the holographic display apparatus are provided. The holographic display apparatus includes: an image generator configured to generate a hologram image by modulating light; an optical system including a freeform curved surface for forming the hologram image generated by the image generator in a predetermined depth; and a processor configured to generate a computer-generated hologram (CGH) based on three-dimensional image information by using a phase map including information about an optical aberration with respect to the freeform curved surface and to control the image generator to modulate the light based on the CGH.

A method for generating a holographic image, a signal processor, a holographic image display device, a wearable apparatus, and an onboard head-up display apparatus. The method comprises: performing holographic transformation on the basis of a target amplitude phase distribution of a target image to obtain a holographic phase image; performing phase quantization of the holographic phase image to obtain a quantized holographic image; performing inverse holographic transformation of the quantized holographic image to obtain a reconstructed image; if the reconstructed image satisfies a preset condition, determining that the quantized holographic image is a target holographic image; if not, constraining the amplitude phase of the reconstructed image and, on the basis of the amplitude phase constrained image, continuing iteration. The present method can rapidly and effectively implement monochrome or multi-colour high contrast ratio, low noise real-time holographic image generation and display, and the imaging distance can be freely adjusted.

The disclosure provides in one aspect a head-up display for a vehicle. The head-up display comprises a picture generating unit, an optical system and a light-selective filter. The picture generating unit is arranged to display a picture on a screen. The optical system is arranged to receive light of the picture. The optical system comprises at least one optical element having optical power arranged to form a magnified image of the picture. The light-selective filter is transmissive to light of the picture and reflective to other light. The light-selective filter is disposed between the optical system and the screen. The light-selective filter has a first surface arranged to receive light from the optical system and a second surface arranged to receive light of the picture from the screen.

A holographic projector comprises an image processing engine, a hologram engine, a display engine and a light source. The image processing engine is arranged to receive a source image for projection and generate a plurality of secondary images from the source image. The source image comprises pixels. Each secondary image comprises fewer pixels than the source image. A first secondary image has more pixels that a second secondary image. The hologram engine is arranged to determine, such as calculate, a hologram corresponding to each secondary image to form a plurality of holograms. Thus, a first hologram corresponding to the first secondary image has more pixels than a second hologram corresponding to the second secondary image. The display engine is arranged to display each hologram in turn on the display device. The light source is arranged to Illuminate each hologram during display to form a holographic reconstruction corresponding to each secondary image on a replay plane.

Disclosed are an active complex spatial light modulation method and apparatus for an ultra-low noise holographic display. The active complex spatial light modulation apparatus includes a substrate and a petal antenna including three petal patterns arranged on the substrate, dividing a complex plane into three phase sections, and modulating the input light into three-phase amplitude values corresponding to the phase sections. The petal antenna may have a point symmetry shape based on the center point of the petal antenna.