There is provided a holographic projector comprising a hologram engine and a controller. The hologram engine is arranged to provide a hologram comprising a plurality of hologram pixels. Each hologram pixel has a respective hologram pixel value. The controller is arranged to selectively-drive a plurality of light-modulating pixels so as to display the hologram. Displaying the hologram comprises displaying each hologram pixel value on a contiguous group of light-modulating pixels of the plurality of light-modulating pixels such that there is a one-to-many pixel correlation between the hologram and the plurality of light-modulating pixels.

A non-destructive iterative interferometric tomographic technique for imaging and reconstruction of phase objects as well as objects with complex permittivity and, particularly, to iterative optical diffraction tomographic (iODT) imaging and reconstruction of phase objects with high refractive index (RI) contrast, complex structures, and/or large optical path differences (OPDs) against the background, which cause multiple scattering, and applications thereof.

A method of operating a display device comprising a drive circuit is disclosed. The drive circuit comprises a plurality of single grey-level channels, each comprising an input (412, 422), an output (418, 428) and a signal processor connected between the input and output. Each signal processor comprises a digital-to-analog converter (414, 424) and an operational amplifier (416, 426) having a voltage offset. The method comprises: converting a digital signal received at the input (412, 422) into an analog voltage (410, 420) at the output (418, 428) using each respective signal processor; switching between the analog voltage (410, 420) of each single grey-level channel using a switching circuit (430); receiving and analysing the analog voltages (410, 420) in a calibration subsystem (440), and individually compensating for the voltage offset of each op-amp (416, 426) based on the received analog voltage (410, 420) for that grey-level channel using the calibration subsystem (440).

A holographic security or identification device (10) comprises an object, or a flexible substrate (12) configured to be conformable to a desired, curved shape; and a plurality of structures (14) formed on or in the object to have a desired curved configuration, or formed in or associated with the substrate and arranged to adopt a desired curved configuration when the substrate is conformed to a desired shape, wherein the plurality of structures (14) are configured to receive light (20) of a selected at least one wavelength or range of wavelengths and to produce, using the received light, a desired holographic image (22) for security or identification purposes when in the desired configuration.

A method is presented for determining a phase of an input beam (110, E.sub.in) without a reference ray. In the method, an input beam (110, E.sub.in) having a plurality of input rays is split into a main beam (112, E1) and a reference beam (114, E2) in such a way that each input ray is split into a main ray of the main beam (112, E1) and a comparative ray of the reference beam (114, E2). The main beam (112, E1) is propagated along a first interferometer arm, and the reference beam (114, E2) is propagated along the second interferometer arm. The propagated main beam (112, E1) and the propagated reference beam (114, E2) are superposed to form an interference beam having a plurality of interference rays. The propagation along the first and second interferometer arms is carried out such that at least one interference ray of the interference beam is a superposition of a main ray of the propagated main beam (112, E1) assigned to a first input ray of the input beam (110, E.sub.in), and of a comparative ray of the propagated reference beam (114, E2) assigned to a second input ray of the input beam (110, E.sub.in) different from the first input ray.

There is provided a holographic image generation system comprising: a spatial light modulator (SLM) having pixels; a light source configured to illuminate the SLM; a temporal modulator; a light sensor associated with the SLM; and a demodulator. The temporal light modulator is arranged to modulate an output intensity of the light source over time to encode holographic data representing a hologram. The light sensor is configured to receive light from the light source and generate a signal representative of the output intensity of the light source. The demodulator is connected to the light sensor to receive the signal, and is arranged to decode the signal to obtain the holographic data. The demodulator is further connected to the SLM to set the pixels of the SLM in accordance with the holographic data to display the hologram ready for illumination by the light source to form a holographic reconstruction.

A method and system for forming a holographic structure in a material. The holographic structure is configured to project a selected target image in the far field under illumination of the holographic structure by a laser. The method calculates a modified design for the holographic structure that encodes a unique identifier within the holographic structure for projecting the target image. The method modifies the material by mapping features corresponding to the modified design into the material so as to form the holographic structure. A basic check of the authenticity of the material is performed by checking whether a projected replica of the target image is as expected. A more detailed check of the authenticity of the material is performed by directly inspecting the features in the holographic structure.

A method of producing a Computer Generated Hologram (CGH) for producing a 3 dimensional (3D) holographic image, including receiving data describing a 3D scene, producing a first CGH for producing a 2D image of the 3D scene as viewed from a specific viewing direction, the 2D image perpendicular to the viewing direction, decomposing the 2D image to a plurality of slices at different depths along the viewing direction, adjusting the first CGH by making, for at least one of the plurality of slices, a correction to the CGH associated with a depth of the slice along the viewing direction, thereby producing a corrected CGH for producing a 3D holographic image of the 3D scene. Related apparatus and methods are also described.

A method for digital holography includes modeling a hologram using a forward propagation model that models propagation of a light field from a hologram plane to an image plane. The method further includes computing the hologram as a solution to an optimization problem that is based on the model. The method further includes configuring at least one spatial light modulator using the hologram. The method further includes illuminating the spatial light modulator using a light source to create a target image.

A phase modulation data generating unit according to the present disclosure includes: a first calculating section; and a storage section. The first calculating section calculates basic phase modulation pattern data on the basis of a partial illumination image pattern that makes it possible to generate an intended illumination image pattern having a desired luminance distribution. The basic phase modulation pattern data makes it possible for a light phase modulation device to reconstruct the partial illumination image pattern. The storage section stores the basic phase modulation pattern data calculated by the first calculating section.