The present invention relates to a method and apparatus for holographic recording based on holographic printing technology, and more specifically, to a method and apparatus for holographic recording, in which the hologram is recorded after the deviation in diffraction efficiency for each hogel is pre-compensated for by varying the intensity (luminance) of the object beam for each hogel during the hologram recording in response to a deviation in diffraction efficiency (reconstruction efficiency) for each hogel of a holographic recording surface that occurs when the hologram is reproduced. Accordingly, the reproduction imbalance of a near-eye display (NED) using a holographic optical element (HOE) is resolved by controlling the diffraction efficiency uniform on the entire holographic recording surface when the hologram is reproduced.

Here discloses a method for duplicating a hologram and a hologram optical element. The method comprises: preparing a master with a master hologram; preparing a sample with coated photoalignment material layer above the master; and irradiating a recording light through the sample to the master, so that at least one portion of the recording light is reflected by the master as an object light carrying the master hologram information, and so that the object light and the recording light are interfered at the photoalignment material layer to produce a duplicated hologram in the photoalignment material layer.

Methods, devices and systems are described that enable monitoring the diffraction efficiency of holographic material in real-time while they are being formed. One example method includes directing a reference beam and an object beam toward a holographic material for formation of a diffraction grating and blocking one of the beams for at least a portion of time during which the diffraction grating is being formed. The method further includes, upon blockage of one of the beams, based on power level measurements, determining whether or not a first diffraction efficiency is reached. If the first diffraction efficiency is reached, one of the reference or the object beams is disabled or blocked while the other beam illuminates the holographic material with a particular duty cycle. Further measurements of the diffraction efficiency are made until the final diffraction efficiency is reached.

The present invention features VHOEs with expanded acceptance angle ranges as well as various systems and methods for fabricating VHOEs with expanded acceptance angle ranges. The VHOE with expanded acceptance angle range may include two or more individual Bragg gratings. In preferred embodiments, the two or more individual Bragg gratings have the same diffraction geometry but with shifted Bragg conditions. Having the same diffraction geometry means when light is incident on the VHOE including two or more individual Bragg gratings, the diffracted light from each of the Bragg gratings is co-linear or overlapping with the diffracted light from the other Bragg gratings. The Bragg condition for each of the Bragg gratings are shifted with respect to each neighboring Bragg grating by an amount up to the acceptance angle range of each individual Bragg grating.

A backlight device, a holographic display that includes the backlight device, and a method of manufacturing a holographic optical element are provided. The backlight device includes a light guide plate configured to guide light emitted by a light source, a first holographic optical element configured to expand light that has propagated through the light guide plate and that has a multi-layered structure, and a second holographic optical element configured to concentrate light reflected by the first holographic optical element.

To provide a hologram, a light-transmissive reflector plate, a screen, and a projection system capable of achieving high transparency and allowing a projected image to be brightly and clearly reflected and observed.

A hologram 1 has a relief part, wherein the hologram 1 reflects a given white light incident thereon at a given angle from one side, while transmits a given white light incident thereon at a given angle from the other side, and diffraction efficiency for transmitted light and diffraction efficiency for reflected light differ from each other.

Diffractive waveplate lenses, mirrors, devices, systems and methods for performing imaging over a broad spectral band in imaging systems, such as but not limited to astronomical imaging, surveillance imaging, and in communication systems, such as laser communication systems. Corrector mirrors are used with a flat diffractive wave diffractive waveplate lens so that chromatic aberrations of the diffractive waveplate lens are reduced with the imaging system.

An imaging module of a projection device generates a multi-color image such that a first color sub-image with a first wavelength and a second color sub-image with a second wavelength are generated. Deflection efficiency curves for a specified angular range about a specified viewing angle are set such that a first efficiency ratio for the specified angular range is constant. The imaging module is actuated such that when the multi-color image is generated, a first brightness ratio of the brightness of the first color sub-image to the brightness of the second color sub-image is inversely proportional to the a efficiency ratio such that different deflection efficiency curves are compensated for and such that the viewer can perceive the multi-color image as a true-color virtual image at viewing angles from the specified angular range.

The present invention relates to a method and apparatus for holographic recording based on holographic printing technology, and more specifically, to a method and apparatus for holographic recording, in which the hologram is recorded after the deviation in diffraction efficiency for each hogel is pre-compensated for by varying the intensity (luminance) of the object beam for each hogel during the hologram recording in response to a deviation in diffraction efficiency (reconstruction efficiency) for each hogel of a holographic recording surface that occurs when the hologram is reproduced. Accordingly, the reproduction imbalance of a near-eye display (NED) using a holographic optical element (HOE) is resolved by controlling the diffraction efficiency uniform on the entire holographic recording surface when the hologram is reproduced.

The invention relates to techniques for producing a holographic optical element, HOE, by replication of a master HOE. More particularly, the invention relates to techniques for flexibly adjusting the diffraction efficiency of the HOE. An adjustable settable optical element (54) can be used to change the intensity and/or polarisation of light during an illumination process.