A new diversity concept is provided for achieving accurate phase retrieval with a singleshot acquisition. Multiple irradiance data are obtained by a diffractive grating or CGH designed to generate multiple diffraction orders with different diversity values. The effective filters associated with the individual diffraction orders from the diffractive grating or CGH are calculated. The effective filters are extracted by numerical propagation, and they preferably include both real and imaginary values, which signify both absorption and phase shift versus position in the filter plane. The reconstruction process utilizes accurate knowledge of the effective filters for each diffraction order for high quality reconstruction of the extrinsic phase.

A light projection system, including a light source to provide an output beam of light, an angular light modulator (ALM) comprising a plurality of pixels, each pixel having an ON state and an OFF state, the ALM positioned to receive output beam on the plurality of pixels, and a processor coupled to the ALM. The processor is programmed to control a first set of the pixels to transition between the OFF state and the ON state while the beam is incident on the pixels. An amount of light is selectively directed in a direction by the first set. The processor is also programmed to control a second set of the plurality of pixels to remain in the OFF state while the beam is incident on the plurality of pixels. As a result, the ALM operates as a spatial light modulator and an angular light modulator of the beam of light.

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.

A phase modulation structure includes a recording surface including phase angle recording regions in a plurality of calculated element regions corresponding to reconstruction points of an image on a one-to-one basis, each phase angle recording region being formed of a plurality of unit blocks in each of which a phase angle is recorded, the phase angle being calculated based on a phase that is a sum of a plurality of phases of light from the corresponding reconstruction points; and a representative area that is one of divisions of the calculated element region, the representative area being obtained by radially dividing the calculated element region centered on a point on the calculated element region, the point being obtained by extending a normal line from the corresponding reconstruction point to the calculated element region on the recording surface.

Techniques related to generating holographic images are discussed. Such techniques include application of a machine learning model to the target image to generate data that is used to enable the determination of a phase pattern via a wave propagation model. The wave propagation model is used to generate holographic data, which is then adjusted according to one or more constraints associated with the holographic display that will be used to generate a holographic image based on the adjusted holographic data.

The present invention provides a surface shape measuring device and a surface shape measuring method which do not require a physical reference plane and can improve measurement accuracy without using a mechanical adjustment mechanism. The illumination light condensing point P.sub.Q and the reference light condensing point P.sub.L are arranged as mirror images of each other with respect to the virtual plane VP, and each data of the object light O, being a reflected light of the spherical wave illumination light Q, and the inline spherical wave reference light L is recorded on each hologram. On the virtual plane VP, the reconstructed object light hologram h.sup.V for measurement is generated, and the spherical wave optical hologram s.sup.V representing a spherical wave light emitted from the reference light condensing point P.sub.L is analytically generated. The height distribution of the surface to be measured of the object 4 is obtained from the phase distribution obtained by dividing the reconstructed object light hologram h.sup.V by the spherical wave light hologram s.sup.V. High-accuracy surface shape measurement without requiring a reference plane such as a glass substrate is realized by comparing the phase data of the reflected light acquired from the surface to be measured and the phase distribution on the plane cut surface of the spherical wave obtained analytically.

A method for producing a holographic optical element. The method includes a step of exposing a recording material to a phase pattern which is provided by a first modulated light beam with a first phase portion. Furthermore, the method includes a step of an additional exposure of the recording material to the phase pattern, which is provided by a second modulated light beam with a second phase portion, wherein the second phase portion has a phase offset with respect to the first phase portion in order to produce a holographic optical element.

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.