Hughes Aircraft Company

Bernard H Soffer

Yuri Owechko

Jan Grinberg

Emanuel Marom

Thomas R O'Meara

Uzi Efron

David M Pepper

Gilmore Joseph Dunning

Melvin E Pedinoff

Richard C Lind

Marvin B Klein

Adrian E Popa

Graham R Nudd

Alexander A Sawchuk

Wilbur P Brown, Jr

Armand R Tanguay, Jr

Pierre H Chavel

Timothy C Strand

An optical beam scanner incorporating an array of beam deflection elements commonly controlled to steer an optical beam impingent on the array is described. The beam steering elements are arranged in the array as individually controlled elements and the deflection of the beam is accomplished by setting the phase tilt and the phase offset of each element according to a calculation which removes modulo 2.pi. phase shift from the required position relative to a flat plane. Thus, the array elements can be thin and need only supply about 2 radians of phase shift. These elements may be incorporated in a planar array using beam deflection elements such as liquid crystal beam deflectors by choosing a drive scheme representing either a blazed array or a flat piston array. Operation may be designed for a large range of light wavelengths and the system may efficiently accommodate a combination of the blazed and flat piston techniques to obtain beam deflection characteristics otherwise unavailable by the exclusive use of each individual technique. By use of the liquid crystal phased array approach, rapid, high accuracy, large area beam deflection is possible without the necessity of any moving parts and with low power drive requirements. Phased arrays of the type described above may be arranged in successive parallel planes with a common beam axis to provide two-dimensional beam deflection.

Phased array for optical beam control

A cascaded adaptive optics system for correction of aberrations in a light beam. The system includes a plurality of spatial light modulators (SLMs) in a cascaded arrangement to provide an adaptive optics system characterized by wide range, rapid response, and high resolution. The spatial light modulators may be identical or have characteristics that are complementary in providing a combined output that advantageously corrects for aberrations. A conventional adaptive optics system such as a deformable mirror may be used as one or more of the SLMKs. Liquid crystal light valves (LCLVs) may be advantageously used as one or more of the SLMs in the invention. A single LCLV may be cascaded with itself in a multiple-pass configuration by means of suitable reflectors.

Cascaded adaptive optics system

Apparatus for compensating for inherent distortions in a modified liquid crystal light valve used in an integrated wavefront sensing and wavefront control system for laser optics. A main wavefront sensing and control system utilizes a liquid crystal light valve selected for response speed but having inherent surface non-linearities. A beam from an auxiliary laser is intermittently applied, while the main laser is blocked, to both the fast response LCLV of the main system and to a slower response LCLV of an associated correction system. The second LCLV system corrects for the non-linearities in the surface of the first LCLV and then maintains the stored correction signal for a decay interval which corresponds to several response times of the main LCLV, thus permitting the main LCLV system to perform fast correction of atmospheric aberrations in the laser beam wavefront unaffected by inherent surface non-linearities.

Method for adaptive correction of the phase non-uniformity of a liquid

An associative memory system is provided which incorporates a spatial light modulator (SLM) and thresholding components. In the preferred embodiment, a Fourier transform hologram is used to convolve a reference beam with correlated input images and stored object images. An iteration and feedback loop is provided which is used to derive an enhanced reference beam for use in matching and enhancing the associative memory of the hologram with the object input plane image. The iteration loop of SLM and optical amplifying components comprises a liquid crystal light valve (LCLV) which receives the correlation plane image and provides that image in the form of a spatially phase-modulated and amplitude modulated signal to a polarizing thresholding analyzer device. The analyzer/polarizer is adjustable and threshold limits the data at fast rates and, is used in the preferred embodiment to threshold the data with reference to the greatest amplitude portion of the correlation spot provided to the LCLV. After the optical analyzer/polarizer threshold has processed the signal, an improved signal is provided to the writing photoconductor side of the LCLV. This processed signal is used to phase-modulate a projection light readout beam. A polarizing beam splitter converts the phase modulation of the readout beam to an amplitude modulation wherein an enhanced reference beam is derived which is processed back to the hologram for readout at the output plane of the system. In this manner a variable-gain fast response spatial light modulator component system is provided for use as an associative memory.

Associative memory system with spatial light modulator

A light deflector apparatus and method is disclosed which provides an optical intensity-to-position mapping as well as optical switching capabilities. An array of voltage gradient modules (24, 26, 28) are provided in a layer of electro-optic material (52), such as liquid crystals, by establishing variable spatial voltage gradients and accompanying electric fields in a direction transverse to input light (58). The voltage gradients are varied in accordance with the optical intensities at corresponding locations in the received light (58), resulting in optical outputs which vary in direction in accordance with the voltage gradient locations. The directional outputs are then focused to produce a positional mapping (64, 66, 68) of the input light intensities. The voltage gradients are preferably established by an interdigitated electrode array (50) and a counter electrode (54) on opposite sides of the liquid crystal (52). Reflective and transmissive light valve embodiments are described in which the voltage gradient modules form voltage dividers with an underlying photoconductive layer (56). A fiber optic switch is also described. Also described is a system in which the refractive indices of an array of small variable refraction modules are varied in accordance with the spatial optical intensities at corresponding locations in an input beam to produce as output, optical intensity-to-position mapping.

Optical intensity-to-position mapping and light deflector apparatus and

An apparatus and method for processing optical beams designed to adaptively spatially threshold or filter an intensity histogram spectrum for re-transformation to a two-dimensional thresholded optical output. Such apparatus and method is used in optical computing and logic processing to selectively pass only certain light intensities, thereby blocking undesirable background noise while passing the desired signals. An incoming histogram light beam, containing an optical position distribution corresponding to the intensity distribution of an original optical beam, is split into first and second beams. The first beam is directed at a light detector array which transforms the optical position intensities of the first bema into directly proportional electrical signals. These signals are sent to a microprocessor which analyzes this input, determines the intensity distribution, calculates the algebraic mean and variance, sets the intensity threshold level based on pre-set information, and sends an electronic voltage signal to an optical selective reflector. The optical reflector, preferably a CCD LCLV, is positioned to receive the second split beam, and is instructed by the electronic voltage signal to selectively reflect only certain optical intensities onto an inverse Fourier transform lens. This lens re-transforms the quasi-one-dimensional second split beam into the desired two-dimensional thresholded optical output.

Optical thresholding apparatus and method

Optical analog data processing systems are described for handling both bipolar and complex data. Multi-cell spatial light modulators are employed in which a plurality of modulation areas are used in conjunction with space and time mutliplexed configurations to process bipolar and complex data elements. Multi-cell light detector arrays are used to convert modulated light into signals representing the processed data. The processing systems are capable of real time processing of synthetic aperture radar data.

Optical analog data processing systems for handling bipolar and complex

A high frequency spectral analysis system and method operates by modulating an optical beam with a high frequency signal to be analyzed, and sampling the beam simultaneously at periodically spaced locations along its length. The sampled portions are then focused to a spectral mapping. In the preferred embodiment a beam is directed in a zigzag pattern through a plate, one surface of which is totally reflective and the opposite surface of which is partially reflective. Periodic parallel samples are obtained from the minor portions of the beam which are transmitted out of the plate through the partially reflective surface. The totally reflective surface is preferably formed as a series of cylindrical surfaces which focus the beam to small spots at the partially reflective surface, thereby permitting a higher spatial density of samples without overlapping. The plate thickness is selected so that the beam is sampled at the Nyquist rate for the highest frequency contained in the signal of interest.

Method and apparatus for ultra high frequency spectrum analysis

An associative memory system incorporating a hologram, a spatial light modulator (SLM) and thresholding components in a feedback loop to derive an enhanced reference beam for use in reconstructing a stored image. In a preferred embodiment, the SLM includes a liquid crystal light valve (LCLV). A polarizing thresholding analyzer device provides adjustable thresholding. An enhanced thresholded reference beam thereby derived is sent back to the hologram for readout and the stored image is reconstructed at the output plane of the system. In an alternative embodiment, two spatial light modulators and two feedback loops are provided in a resonator configuration.

Associative memory system with spatial light modulator and feedback for

Optical data processing systems are described for processing four NxN matrices A, B, C, D to calculate the expression CA.sup.-1 B+D. Multi-cell spatial light modulators are employed in conjunction with control circuits to perform matrix inversion, multiplication and addition.

Optical data processing systems and methods for matrix inversion,

Methods of performing complex optical computations, preferably using a programmable optical data processor having a plurality of spatial light modulators to impress data onto a data beam. Data can be applied to a subset of the modulators so as to impress a corresponding data image onto the beam; with uniform data applied to the remaining ones of the modulators so as to impress corresponding uniform data images onto the beam such that the computation performed is dependent on the data applied to the subset of the modulators. Any one of a number of performable optical computations can be programmably performed by providing data to selected subsets of the plurality of spatial modulators.

Programmable methods of performing complex optical computations using

Associative holography memory apparatus is disclosed which employs a hologram, two phase conjugate mirrors, and a two-wave mixing contra-directional coherent image amplifier. The mirrors and amplifier are arranged to form a conjugate resonator whereby the output image from the apparatus tends to converge to that stored image most closely associated with an input image. Alternate embodiments are described which employ a multiple storage and erasure hologram, and which employ only a single phase conjugate mirror.

Associative holographic memory apparatus employing phase conjugate

An optical data processing system employing a programmable optical data processor for processing an optical data beam comprising a plurality of zero, one and two-dimensional modulators for spatially modulating the optical data beam, the modulators being interconnected such that lenses are not necessary to accomplish the focusless transfer of the optical data beam between the modulators. The plurality of modulators are controlled so as to permit the programmable processing of the optical data beam. The optical data processor realized is physically solid and compact and is readily capable of performing a wide variety of optical computations.

Programmable multistage lensless optical data processing system

Associative holography memory apparatus is disclosed which employs a hologram and two phase conjugate mirrors. The mirrors are arranged to form a conjugate resonator whereby the output image from the apparatus tends to converge to that stored image most closely associated with an input image. Alternate embodiments are described which employ a multiple storage and erasure hologram, and which employ only a single phase conjugate mirror.

Growing community of inventors

Pacific Palisades, CA, United States of America

Bernard H Soffer