Hazeltine Corporation

Northrop Grumman Systems Corporation

Frederick W Freyre

Richard LaRosa

An optical correlator includes at least one electrically addressable liquid crystal array, at least one LED array for generating a reference image which is modulated by changing the transmissivity of the liquid crystals in the liquid crystal array, and at least one two-dimensional large size photodiode, the photodiode receiving a modulated image from the liquid crystal array. LED and liquid crystal array are stacked together with a photodiode or an array of photodiodes with no space between, for an exceptionally simple, compact and inexpensive optical correlator structure.

Space integrating sliding image optical correlator

A flat panel display system is provided in which the pixels thereof are illuminated by optical fibers. Economy and compactness are achieved by using micromechanical light modulators to demultiplex light from a limited number of LED's to a large number of pixels. By using micromechanical light modulators incorporated in an integrated circuit, the flat panel display system is relatively economical, has low power consumption, and produces a display of very high resolution. The display also may be provided in full color.

Flat panel display system and method

Coherent light is incident upon an acousto-optical cell through which bulk acoustic waves are propagating. These acoustic waves correspond to a signal to be detected and cause periodic variations in the refractive index of the cell which interact with the coherent light. Acoustic frequency components of the propagating waves cause the cell to diffract beams of incident coherent light in a unique direction and to frequency shift each beam of diffracted light. The relative phases of the acoustic frequency components are also imparted to the respective diffracted light beams. Diffracted and undiffracted coherent light beams are recombined so that optical heterodyning takes place. The recombined light beams are focused by a Fourier Transform lens onto a photomixer which detects the frequency difference between the diffracted and undiffracted light beams. By detecting the recombined light beams with a photomixer array or, by deflecting the position of the undiffracted light or by amplitude or phase modulating the undiffracted light, a channelized coherent acousto-optical receiver is achieved which may function as part of a rapidly tunable bandpass filter.

Acousto-optical channelized processor

Coherent light is incident upon an acousto-optical cell through which bulk acoustic waves are propagating. These acoustic waves correspond to a signal to be detected and cause periodic variations in the refractive index of the cell which interact with the coherent light. Acoustic frequency components of the propagating waves cause the cell to diffract beams of incident coherent light in a unique direction and to frequency shift each beam of diffracted light. The relative phases of the acoustic frequency components are also imparted to the respective diffracted light beams. Diffracted and undiffracted coherent light beams are recombined so that optical heterodyning takes place. The recombined light beams are focused by a Fourier Transform lens onto a photomixer which detects the frequency difference between the diffracted and undiffracted light beams. By detecting the recombined light beams with a photomixer array or by deflecting the position of the undiffracted light, a channelized coherent acoustic-optical receiver is achieved which may function as part of a rapidly tunable bandpass filter.

Acousto-optical signal detector

Apparatus for translating the position of a coherent beam of light using one or more acousto-optical cells. The beam is incident upon an acousto-optical cell through which acoustic waves of a selected frequency are propagating. These acoustic waves cause periodic variations in the refractive index of the cell which act to diffract and frequency shift the beam by amounts which are determined by the frequency of the acoustic wave. The once-diffracted beam is reflected back through the acosto-optical cell in the opposite direction, which causes a diffraction and frequency shift which are equal and opposite to the initial diffraction and frequency shift. By varying the frequency of the propagating waves, the final output beam of coherent light can be translated without a frequency shift. Also disclosed are a dual, identical Bragg cell embodiment for translating a light beam and dual Bragg cells having differing acoustic propagation velocities for deflecting a light beam.

Acousto-optical apparatus for shifting a beam of light

Coherent light is incident upon an acousto-optical cell through which bulk acoustic waves are propagating. These acoustic waves correspond to a signal to be delayed and result from the application of the signal to a piezoelectric transducer of the cell. The waves cause periodic variations in the refractive index of the cell which interact with the coherent light. Acoustic frequency components of the propagating waves correspond to the signal frequency components and cause the cell to diffract the beam of incident coherent light and to frequency shift the diffracted beam. The relative phases of the acoustic frequency components of the acoustic waves also correspond to the phases of the frequency components of the signal to be delayed and are imparted to the respective diffracted light beams. The diffracted light is combined with undiffracted coherent light so that optical heterodyning takes place. The recombined light is focused by a Fourier transform lens onto a photomixer which detects the frequency difference between the diffracted and undiffracted light beams. This detected frequency difference corresponds to the signal to be delayed. The delay time is the time required to convert the signal to corresponding acoustic waves and to optically detect the waves. The delay time is equal to the time required for the acoustic waves to propagate from the transducer to the point of incidence of the coherent light on the cell. Deflecting the coherent light incident upon the acousto-optical cell varies the point of incidence on the cell and, therefore, the delay time.

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Wantagh, NY, United States of America

Frederick W Freyre