A method for digitally generating a hologram plane from a three-dimensional scene, cut into a plurality of planes parallel to the hologram plane. The method includes for a current plane: counting a number of points of the non-zero amplitude scene; choosing a first or second technique for propagating a light wave emitted by the current plane as a function of a number of points of non-zero amplitude included in the current plane and with a preset threshold value, the first, point-based technique calculating the propagation of a sum of light waves emitted by point sources constituted by the points of the scene portion of a non-zero amplitude of the current plane on a following plane, and the second, field-based technique, globally calculating a light wave emitted by the scene portion situated in the current plane on a given plane; and processing the current plane according to the chosen propagation technique.

An apparatus for manufacturing a hologram includes a holographic optical element on which a first interference pattern of a first signal beam and a first reference beam is recorded and a second interference pattern of a second signal beam modulated by a Fourier lens and a second reference beam is recorded. Also, an apparatus for reconstructing a hologram by using the holographic optical element is provided.

A method and an apparatus for reconstructing a Computer-Generated Hologram from a multiple plane image are provided. Reconstructing the Computer-Generated Hologram comprises decoding data representative of at least one patch of at least one layer of the multiple plane image, the data comprising a first location for placing the patch in a first image of the multiple plane image, the first location being used for placing reconstructed content of the patch in a 3D scene, and determining for the at least one patch a second location for placing the patch in a second image, the second image being intended to be used for determining the Computer-Generated Hologram.

A hologram recording device includes a light outputting unit that sequentially outputs multiple laser beams such that the laser beams are coaxially aligned, the laser beams having different wavelengths and being emitted from multiple laser beam sources, an optical system that generates a reference beam and an object beam, with which a hologram is recorded, from each of the laser beams output from the light outputting unit, and an adjusting unit that adjusts a relative position of a recording medium and a focus position of the object beam generated from each of the laser beams having different wavelengths so that the object beam is focused on a surface of the recording medium when the hologram recording device records multiple holograms in a wavelength multiplex recording by sequentially applying the object beams and the reference beams to the recording medium.

Hybrid white-light viewable holograms and methods for making them. The holograms are hybrid reflection holograms made using the diffractive structures or gratings of a holographic object such as a transmission hologram or holographic optical element (HOE). The wavefronts of the diffractive structures are converted into a reflection hologram by scanning them with a coherent light source having a profiled narrow beam. The hybrid reflection hologram can exhibit display parameters including the multiple colors, solidity, and color stability of white light reflection holograms, the diffractive color shifting of a white light transmission hologram, three dimensional imaging and a wide variety of dynamic changes. Different areas or images with each of these effects can be combined in a single hologram. These hybrid reflection holograms are ideal for security and forgery prevention applications.

The present disclosure discloses a hologram recording device and a hologram recording method. The hologram recording device comprises an object imaging unit comprising a cavity for accommodating an object whose interior wall is a reflective surface, and a light modulating unit configured to produce incident light and reference light interfering with the incident light and to direct the incident light to the object imaging unit. The cavity is provided with an imaging aperture for imaging of the object and at least one light incidence aperture for allowing the incident light to enter the cavity and irradiate on the object, such that an image of the object is formed at a location corresponding to the imaging aperture outside the cavity, and image light produced upon the imaging of the object interferes with the reference light at the location for recording of an image surface hologram.

Disclosed herein is an apparatus for recording a hologram. The apparatus for recording a hologram according to the present specification may include a light source unit configured to illuminate an object with light, a housing having a predetermined shape and configured to block outside light, a coupling unit to which a recording medium having a photopolymer composition applied thereto is coupled, a lens unit positioned at a front surface of the housing and configured to form an image on the coupling unit, a filter unit, a backlight unit, and a controller.

A projection system that facilitates the use of in-situ detection of a change in wavelength, thereby enabling appropriate compensation or corrections to be applied on the fly to improve the quality of the image in the primary image region. In-situ detection in this manner can allow wavelength changes due to both temperature fluctuations and hardware variations to be compensated for simultaneously, thereby reducing the time and expense for end of line hardware testing, and removing the need to perform in-situ mapping of the wavelength as a function of temperature. In this way, the quality of the image provided to a user can be improved in a simpler, more efficient manner.

A focus adjustment method for acquiring an image of a surface of interest of a sample by a holographic imager includes the steps of: placing the sample including at least one reference object having a known shape and described by characterising parameters having at least position parameters acquiring an image and determining the position of the reference object with respect to the acquisition plane, by applying a light diffraction model involving the spatial parameters of the reference object estimated by approximating the appearance of the reference object in the holographic image acquired, and determining the position of the surface of interest with respect to the acquisition plane from a position of the reference object and focus adjustment of the image acquisition.