64 results about "Photorefractive crystal" patented technology

Improvements to the acquisition and replay systems for direct-to-digital holography and holovision are described. A method of recording an off-axis hologram includes: splitting a laser beam into an object beam and a reference beam; reflecting the reference beam from a reference beam mirror; reflecting the object beam from an illumination beamsplitter; passing the object beam through an objective lens; reflecting the object beam from an object; focusing the reference beam and the object beam at a focal plane of a digital recorder to form an off-axis hologram; digitally recording the off-axis hologram; and transforming the off-axis hologram in accordance with a Fourier transform to obtain a set of results. A method of writing an off-axis hologram includes: passing a laser beam through a spatial light modulator; and focusing the laser beam at a focal plane of a photorefractive crystal to impose a holographic diffraction grating pattern on the photorefractive crystal. A method of replaying an off-axis hologram includes: illuminating a photorefractive crystal having a holographic diffraction grating with a replay beam.

A light source device is provided with a coherent light source for emitting the coherent light, and a pattern changer for changing an interference pattern of the coherent light on a surface of the illumination object. The pattern changer includes a photorefractive crystal which is arranged between the coherent light source and the illumination object and on an optical path of the coherent light and exhibits a photorefractive effect, and a changer for changing at least one of a light intensity distribution, a polarization direction, a wavelength and an intensity of coherent light incident on the photorefractive crystal. The illumination object is illuminated with the coherent light.

A system and method of detecting acousto-photonic emissions in optically turbid media that provide increased levels of detection sensitivity. The detection system includes an ultrasonic transducer, a laser, a photo-detector for detecting ultrasound-modulated laser light, and circuitry for processing the detected signals for subsequent analysis. The ultrasonic transducer generates an ultrasonic wave that propagates within an optically turbid medium. The laser generates a coherent light beam, which is split to form signal and reference beams. The signal beam is sent through the turbid medium, where it is phase modulated by the ultrasound. The ultrasound-modulated signal beam is provided to a photo-refractive crystal for subsequent interference with the reference beam to convert the phase modulation to intensity modulation. The DC offset of the signal beam intensity provides a measure of the magnitude of the mean phase shift induced by the ultrasound on the multiply scattered optical field within the turbid medium.

A hologram recording and reproducing apparatus preforms to record data on a recording medium and reproduce data from the recording medium. The recording medium is made of a photorefractive crystal having a parallel plate shape. The apparatus includes: a support portion for detachably supporting and rotating the recording medium; a recording-reference-light-beam-supplying-portion for supplying a coherent recording reference light beam propagating along an optical axis to a major surface of the recording medium; a signal-light-beam-supplying-portion for supplying a coherent signal light beam which is modulated in accordance with image data, in an optical path into the recording medium such that the signal light beam intersects with the reference light beam to produce an optical interference pattern with the reference and signal light beams within the recording medium; a reproducing-reference-light-beam-supplying-portion for supplying into the recording medium a coherent reproducing reference light beam propagating in an opposite direction along the optical axis of the recording reference light beam to generate a phase conjugation wave from a refractive-index grating of the light interference pattern; a splitting portion for splitting the phase conjugation wave from the optical path of the signal light beam to image a dot pattern with the phase conjugation wave; a photo-detecting portion for detecting the dot pattern imaged with the phase conjugation wave to reproduce the image data.

The invention discloses a method for photoinduction photorefractive crystal surface microstructure, which comprises the following step: the first step, a photorefractive crystal is selected and irradiated with non uniform light; the space distribution of a space charge field is formed between the surface and the interior of the photorefractive crystal; the second step, the surface of the photorefractive crystal adopts micro-nano granules by electrophoresis or dielectrophoresis effect; and finally the micro structure which has corresponding relation with the space distribution of the space charge field is formed on the crystal surface. The invention provides the method for photoinduction photorefractive crystal surface which has simple operation, can prepare metal microstructure without needing an optical resist, simultaneously has no use for getting help from expensive devices with high pressure and high vacuum, and the like, and is beneficial to widely popularization and application.

The invention relates to a real-time optical image encryption method and its device. In which, using the linear polarizing light as the carrier of the original optical image information, the light interacts with the encryption body, then it interferes with the coherent light into the encrypted interfered light and enters into transmission. During the decryption process, using the reversible optical principle, the encrypted coherent light is received by the photorefractive crystal and interacts with the coherent light and the mentioned encryption body in an opposite sequence, then it shows on a detector output. The described encryption body includes at least one computer controlled spatial light modulator.

A system and corresponding method are described for multi-frequency ultrasonically-encoded tomography of a target object. One or more probe inputs generate probe input signals to the target object. An ultrasound transducer array is placed on the outer surface of the target object and has multiple ultrasound transducers each operating at a different ultrasound frequency to generate ultrasound input signals to a target probe volume within the target object. A photorefractive crystal mixes scattered light output signals from the target probe volume with an optical reference beam input to produce optical tomography output signals including ultrasound sum frequencies components. A photodetector senses the optical tomography output signals from the photorefractive crystal. A tomography analysis of the tomography output signals including the ultrasound sum frequencies components is performed to create a three-dimensional object map representing structural and/or functional characteristics of the target object.

A sensor for remotely detecting an object, the sensor comprising:

• • a light source having a coherence length that is short relative to the distance between the sensor and the object;
  • a splitter splitting the emitted light beam into an incident beam and a reference beam;
  • a photorefractive crystal recording a hologram on interfering reception of the reference beam and of the reflected beam reflected by an object illuminated by the incident beam, and playing back the hologram in a diffracted beam that is re-emitted by the crystal by anisotropic diffraction under the effect of the reference beam;
  • a detector recording information on receiving the diffracted beam; and
  • a polarizing filter that eliminates the major fraction of the reflected beam as transmitted by the crystal on receiving the reflected beam; such that the detector receives only the diffracted beam from the crystal. Both the sensor and imaging systems incorporating the sensor enable measurements to be made through diffusing media.

The present invention discloses an external cavity semiconductor laser, comprising a semiconductor laser tube, a monoblock annular F-P cavity and a photorefractive crystal. The laying of each part in the semiconductor laser allows that: a light beam emitted from the semiconductor laser tube enters into the monoblock annular F-P cavity through an input surface of the monoblock annular F-P cavity, and is returned to the incidence point in the input surface after being reflected by at least two reflecting surfaces; and a transmitted light through one of the reflecting surfaces of the monoblock annular F-P cavity, which is made as an emergent light of the monoblock annular F-P cavity, enters into the photorefractive crystal, and is fed back to the semiconductor laser tube according to the original route. The present invention can realizes an output-stabilized narrow line width and a single-mode wide range of tune, simultaneously solves the problem that the stability of a discrete element F-P cavity is not good and vulnerable to outside interference, the volume of the F-P cavity is too large, and the system is complicated.

The invention provides a dual acousto-optic modulation phase conjugate heterodyne detection device. The device is characterized in that light energy can be effectively utilized, the device is suitable for weak signal measurement, the vibration and spectrum of micro vibration can be obtained, a Soleil-Babnet phase compensator can be used to obtain the phase generated by the amplitude of micro vibration; by comparing a reference light path and a measurement light path, the common mode noise generated by an environmental factor change is greatly reduced, and the measurement precision is improved; the phase conjugate light with a phase compensation characteristic generated by a photorefractive crystal is used, the 'speckle noise' generated by the surface of a detected object is eliminated, and the surface of the detected object is expanded to a comparatively rough surface from an approximate mirror; a dual acousto-optic modulator is used to obtain two mutually vertical orthogonal polarized light, the influence of acousto-optic modulator light intensity modulation is eliminated, the high precision measurement of the amplitude is easy to realize; and the beat frequency of the dual acousto-optic modulator is an intermediate frequency difference, the processing of a low frequency signal in a radio frequency range is realized, and the interference of a low frequency noise is eliminated.

A holographic memory system and apparatus, and a method provide the ability to store multibit holograms in a photorefractive crystal. A single laser diode is configured to emit a collimated laser beam to both write a page of multibit data to and read the page of multibit data from the photorefractive crystal. A multilevel spatial light modulator (DMDSLM) is configured to encode the page of multibit data on an input beam split from the collimated laser beam. A first imaging relay lens pair is positioned between the multilevel spatial light modulator and the photorefractive crystal to image a multibit spatial light modulator image on a plane behind the photorefractive crystal. One or more mirrors are configured to steer a reference beam, split from the collimated laser beam, at high speed to the photorefractive crystal to read or write a page of the multi-bit data.

The invention relates to a recording medium, a manufacturing method thereof, a holographic recording device, a holographic reproducing device and a holographic system; wherein the recording medium, the manufacturing method thereof, the holographic recording device, the holographic reproducing device and the holographic system belong to the field of display technology. The recording medium comprises two transparent conductive film layers and a liquid crystal layer between the two transparent conductive film layers, wherein quantum dots are doped in the liquid crystal layer. According to the recording medium, the manufacturing method thereof, the holographic recording device, the holographic reproducing device and the holographic system, through utilizing the liquid crystal layer in which the quantum dots are doped, spatial charge fields which are generated by the quantum dots increase realignment of liquid crystal modules and increasing target object information recording speed of the recording medium. Problems of relatively low object information recording speed and relatively low holographic recording realization speed in a photorefractive crystal as the recording medium in related technology are settled. An effect of quick object target information recording by the recording medium is realized. Furthermore holographic reproduction efficiency is improved.

A system and corresponding method are described for multi-frequency ultrasonically-encoded tomography of a target object. One or more probe inputs generate probe input signals to the target object. An ultrasound transducer array is placed on the outer surface of the target object and has multiple ultrasound transducers each generating a different time-dependent waveform to form a plurality of ultrasound input signals to a target probe volume within the target object. A photorefractive crystal mixes scattered light output signals from the target probe volume with an optical reference beam input to produce optical tomography output signals including ultrasound sum frequencies components. A photodetector senses the optical tomography output signals from the photorefractive crystal. A tomography analysis of the tomography output signals including the ultrasound sum frequencies components is performed to create a three-dimensional object map representing structural and/or functional characteristics of the target object.

The invention discloses a light diffraction device, a display substrate, a touch substrate and a manufacturing method of the touch substrate. The light diffraction device is used for diffracting emergent lights of the display substrate and comprises a photorefractive crystal block, an electrode structure and a control structure, wherein the photorefractive crystal block is corresponding to at least one pixel unit in the display substrate, and the photorefractive crystal block is preformed with holographic grating; the electrode structure is arranged on two opposite side surfaces of the photorefractive crystal block; and the control structure is used for inputting voltage to the electrode structure, and an electric field is formed between the two opposite side surfaces of the photorefractive crystal block, and at least part of the emergent lights passing through the display substrate is diffracted after passing through the holographic grating under the action of the electric field. By virtue of the light diffraction device disclosed by the invention, the aim that viewing angle and brightness of light rays can be controlled is achieved, so that user experience effect is improved.

A method, apparatus, and system provide the ability for storing holograms at high speed. A single laser diode emits a collimated laser beam to both write to and read from a photorefractice crystal. One or more liquid crystal beam steering spatial light modulators (BSSLMs) steer a reference beam, split from the collimated laser beam, at high speed to the photorefractive crystal.

This invention relates to a scanning ultrasound detection device using two-wave mixing in photorefractive crystal interferometry. An interferometer with two-wave mixing in photorefractive crystal, and cooperates with a confocal lenses module to perform a scan and inspection of the surface of a target. A rotating unit is used for directing a signal beam for detection to be incident upon different locations of the target. The confocal lens module is used to compensate any changes of reflection path caused by the signal beam having different incident angles. Hence, a reflected signal beam and a reference beam can strike on a photo detector.