A holographic display and a method, performed by the holographic display, of forming a holographic image are disclosed. The holographic display includes an electrically addressable spatial light modulator (EASLM); a diffractive optical element (DOE) mask array arranged on the EASLM; and a controller configured to operate the holographic display to form a hologram image, wherein the controller is further configured to address the EASLM to backlight the DOE mask array required to form a set of hologram image voxels by turning on a corresponding EASLM pixel.

A hologram reproducing apparatus is provided that includes a display configured to display a hologram pattern and emit a write beam corresponding thereto, a relay lens disposed at a front surface of the display and comprising an array of microlenses each focusing the write beam, a spatial light modulator (SLM) disposed at a front surface of the relay lens, configured to write the hologram pattern according to the focused write beam and modulate a reproduction beam into a plurality of diffraction beams if the reproduction beam is incident, a light guide plate disposed between the relay lens and the SLM and configured to guide the reproduction beam toward the SLM, a filter disposed at a front surface of the SLM and configured to filter the plurality of diffraction beams and the write beam, and a lens configured to focus the plurality of diffraction beams filtered through the filter.

Provided is a multi-image display apparatus including a light source configured to emit light, a spatial light modulator configured to provide a first image by modulating the light emitted from the light source, and an optical system configured to transmit the first image provided by the spatial light modulator to a viewer, wherein the optical system is configured such that a travelling path of the first image provided by the spatial light modulator includes a first optical path in a first direction, a second optical path in a second direction orthogonal to the first direction, and a third optical path in a third direction orthogonal to the first direction and the second direction, respectively, and wherein the optical system is configured such that the first image and a second image provided from an optical path different from the travelling path of the first image are provided to the viewer.

A holographic display system includes a light source that emits coherent light; a lateral displacement beam splitter that optically receives the coherent light and generates first reference light and second reference light; a first spatial light modulator (SLM) and a second SLM that optically receive the first reference light and the second reference light respectively, and construct first phase-only function (POF) light and second POF light respectively; a first beam splitter and a second beam splitter that optically receive the first POF light and the second POF light respectively, and generate first split light and second split light respectively; and a plurality of polarizers disposed between the first SLM and the first beam splitter, and between the second SLM and the second beam splitter, respectively.

A holographic display apparatus for providing an expanded viewing window includes a spatial filter configured to separate a plurality of holographic images generated by the hologram pattern displayed on the spatial light modulator from a plurality of lattice spots generated by a physical structure of the spatial light modulator. The spatial filter includes a plurality of color filters or a plurality of dichroic mirrors separating a first color image, a second color image, and a third color image from a first color lattice spot, a second color lattice spot, and a third color lattice spot.

Techniques for modulating both amplitude and phase via a layer of liquid crystals are described. According to one aspect of the techniques, a voltage being applied or coupled across the layer of liquid crystals is controlled by gradually increasing the voltage from a low level to a high level to perform the AM in a first range and the PM in second range, where the characteristics of the liquid crystals is significant, for example, by increasing the thickness or optical birefringence of the layer of liquid crystals.

Architecture and designs of modulating both amplitude and phase at the same time in spatial light modulation are described. According to one aspect of the present invention, nano-imprinting lithograph (NIL) and E-beam are used to create micro structures (transparent) as alignment cells. A first group of the alignment cells are oriented in a first direction and a second group of the alignment cells are oriented in a second direction, light going through the first group of the alignment cells is modulated in amplitude thereof and the light going through the second group of the alignment cells is modulated in phase thereof, all via the liquid crystals and at the same time.

Architecture and designs of modulating both amplitude and phase at the same time in spatial light modulation are described. According to one aspect of the present invention, light propagation is controlled in two different directions (e.g., 0 and 45 degrees) to perform both amplitude modulation and phase modulation at the same time in liquid crystals. In one embodiment, a mask is used to form a pattern, where the pattern includes an array of alignment cells or embossed microstructures, a first group of the cells are aligned in the first direction and a second group of the cells are aligned in the second direction. Depending on applications, two cells from the first group and the second group may correspond to a single pixel or two neighboring pixels, resulting in amplitude modulation and phase modulation within the pixel or within an array of pixels.

An optical device comprises a pixel array including one or more pixels. Two or more independently controllable electrodes are electrically coupled to each pixel. A common ground reference electrode is electrically coupled to all pixels of the pixel array. Each pixel includes a plurality of liquid crystal molecules. The liquid crystal molecules may be oriented in a first direction based on a first function of voltages applied by the two or more independently controllable electrodes for the pixel, and oriented in a second direction based on a second function of the voltages applied by the two or more independently controllable electrodes for the pixel. In this way, both phase modulation and polarization modulation may be introduced to light illuminating the pixel array.

The present disclosure provides an optical modulation device, an optical modulation method and a holographic display apparatus. The optical modulation device is configured to perform optical modulation of a light beam and comprising: an amplitude modulator, configured to perform amplitude modulation of the light beam based on amplitude information in complex amplitude information of each pixel of a digital hologram; an optical scanning assembly, configured to scan the light beam within a predetermined range; a phase modulator, configured to perform phase modulation of the light beam based on phase information in the complex amplitude information.