An infrared imaging signal is generated to illuminate tissue. An infrared image of an exit signal of the infrared imaging signal is captured. The infrared imaging signal is within a frequency band.

A device and a method for manufacturing holographic optical elements. The device includes at least two partial light beams and one interference light beam, one deformable mirror in each case per partial light beam, a control unit, which is configured to actuate the deformable mirrors to adapt a wavefront of the partial light beam, and a holographic film. The deformable mirrors are situated so as to each reflect precisely one partial light beam and to direct the reflected partial light beam on the holographic film, and the interference light beam being directed on the holographic film to interfere with the reflected partial light beams so as to simultaneously generate at least two holographic optical elements.

A holographic display apparatus includes: a light source; a spatial light modulator configured to modulate light from the light source according to an image to be displayed on an object plane; and a processor configured to generate a computer generated hologram (CGH) in which a phase value of hologram data to be displayed on a reference plane of the spatial light modulator is 0, the processor being configured to apply a light modulation signal based on the CGH to the spatial light modulator.

In described examples, a system (e.g., a projection system) can include a diffractive optical element adapted to be illuminated by at least one coherent light beam. A lens array is coupled to receive a diffracted beam of light from the diffractive optical element. The lens array includes a first and a second array lens. The first array lens is coupled to receive a first sector of a pattern of illumination of the diffracted beam of light, and the second array lens is coupled to receive a second sector of the pattern of illumination of the diffracted beam of light. A spatial light modulator is coupled to receive overlapping diffracted beams of light from the first and second array lenses to form an image beam.

A method displays a binocular hologram image. The method includes generating a light beam of an incident wave field having coherence, expanding the generated light beam to the size of the active area of a display, converging the expanded light beam on the respective positions of the eyes of a user, generating digital hologram content, and displaying a hologram image based on the converged light beam and on the digital hologram content.

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.

A display pixel array is illuminated by infrared light in a frequency band. An infrared holographic imaging signal is generated by driving a holographic pattern onto the display pixel array. An image of an exit signal of the holographic infrared imaging signal is captured with an image pixel array. The image pixel array is configured to capture the infrared light and reject light outside the frequency band.

A method of calculating a hologram having an amplitude and a phase component. The method comprises (i) receiving an input image comprising a plurality of data values representing amplitude. The method then comprises (ii) assigning a random phase value to each data value of the plurality of data values to form a complex data set. The method then comprises (iii) performing an inverse Fourier transform of the complex data set. The method then comprises (iv) constraining each complex data value (X1, X2) of the transformed complex data set to one of a plurality of allowable complex data values (GL1-GL8), each comprising an amplitude modulation value and a phase modulation value, to form a hologram, wherein, the phase modulation values (GL1-GL7) of the plurality of allowable complex data values substantially span at least 3π/2 and at least one of the allowable complex data values has an amplitude modulation value of substantially zero (GL8) and a phase modulation value of substantially zero.

A three-dimensional (3D) display system includes a reference spatial light modulator configured to generate a reference wavefront. The system also includes an object spatial light modulator configured to generate an object wavefront. The system further includes a Hogel basis display positioned between the reference spatial light modulator and the object spatial light modulator. The Hogel basis display is configured to receive the reference wavefront and the object wavefront. The Hogel basis display is also configured to generate a light field based at least in part on interference between the reference spatial light modulator and the object spatial light modulator.

There is provided a holographic projector comprising a reflective liquid crystal display device. The reflective liquid crystal display device comprises a light-modulating layer between a first substrate and a second substrate substantially parallel to the first substrate. The light-modulating layer comprises planar-aligned nematic liquid crystals having positive dielectric anisotropy. The first substrate is substantially transparent and comprises a first alignment layer arranged to impart a first pre-tilt angle θ.sub..Math. on liquid crystals proximate the first substrate, wherein θ.sub.1>5°. The second substrate is substantially reflective and comprises a second alignment layer arranged to impart a second pre-tilt angle Θ.sub.2 on liquid crystals proximate the second substrate, wherein θ.sub.2>5°. The reflective liquid crystal display device further comprises a plurality of pixels defined on the light-modulating layer having a pixel repeat distance x, wherein x≤10 μm. The distance d between inside faces of the first substrate and second substrate satisfies 0.5 μm≤d≤3 μm, and the birefringence of the liquid crystal Δη≥0.20. The holographic projector further comprises a display driver arranged to drive the reflective liquid crystal display device to display a hologram by independently-driving each pixel at a respective modulation level selected from a plurality of modulation levels having a phase modulation value.