Lockheed Martin Corporation

General Electric Company

Joseph Lawrence Chovan

William Arthur Penn

Lawrence Richard Snowman

Donald Winfield

William Pattee Whyland

Martin Francis Lowry

Evelyn Hope Monsay

Jerome Johnson Tiemann

William E Engeler

Walter Beeman

A method for sensing acoustic energy as the energy passes from a more dense to a less dense medium while compensating for energy level loses that may have occurred along the acoustic path of the acoustic energy. The method may be used to replace a multi-sensor system for detecting acoustic energy. The method includes permitting the acoustic energy to progress from a first transmitting medium to a second transmitting medium, the first transmitting medium being more dense than the second transmitting medium and the first medium being contiguous with the second medium along a predetermined interface; disposing an optical sensor in the second medium so that at least a portion of the acoustic energy imposes a modulation proportional to the frequency components of the acoustic energy on a sampling light emitted by the optical sensor; and detecting at least a portion of the sampling light having modulation in response to the portion of the acoustic energy.

Method for sensing acoustic energy

A sensor array includes a plurality of sensor locations at which sensed signals are produced. A tension element holds locations at a given maximum spacing. The tension element includes an optical fiber. Light propagating on the optical fiber is applied to converters at each location for generating electrical power for the electrically powered portions of the array. The electrically powered portions may be a part of the sensor suite at each location, telemetry equipment, or both.

Sensor arrays having light-powered transducers

The present invention relates to an optical sensor of air borne acoustic waves. The sensor comprises means for producing mutually coherent optical sampling and reference beams, which may be combined to form an intermediate frequency carrier, the sampling beam being exposed to the acoustic field, in which acoustic wave induced density variations occur. These density variations produce a variation in the index of refraction and thereupon a phase modulation of the sampling beam. This phase modulation may be recovered by an optical detector and a phase detector as an electrical signal representative of the acoustic signal. The invention has application to security systems.

Sensor for optically sensing air borne acoustic waves

A system and method for monitoring deformations in a cavity comprising a method for sensing deformations within a body comprising inserting into the body an optical, deforrmable probe having a plurality of imaging devices spaced at predetermined positions within the probe, providing a light source for illuminating the probe at a first time instant, processing first composite imaging information in response to activation of the light source; at a second time instant, processing second composite imaging information in response to activation of the light source; and comparing the processed first and second imaging information to obtain positional information indicative of movement of at least a portion of the probe occurring between the first and second time instants.

Distributed displacement sensor

An underwater viewing system includes a dry and wet end. Illumination energy is provided to the wet end where it is scanned and the resulting scanned illumination is directed to a scene of interest. Energy reflected from the scene is received by the wet end where it retraces the path of illumination to the dry end. The received energy is directed to a detector and ultimately to a video processor. The wet end may be disposed in a remote piloted vehicle with optical waveguide payed out from the dry end to supply the illumination and to conduct the received energy. Communication information may be transferred between the dry and wet end may be over the same path followed by the illumination energy but at a different frequency. The illumination and communication energy may be separated based on their frequency. A polarization device may be provided for maximizing the amount of received energy that is provided to the detector.

Underwater viewing system for remote piloted vehicle

The invention relates to holography and more particularly to an electronic holographic apparatus whose electrical output represents the magnitude and phase of coherent light reflected from a three-dimensional object and distributed over the aperture of the apparatus. The apparatus provides a coherent beam which illuminates the object to create a speckle pattern in an aperture bounding an optical sensing arrangement. A reference beam derived from the same source as the illuminating beam illuminates the sensing aperture directly and creates fringes in the speckle pattern. The optical sensing arrangement consists of a charge injection device (CID) camera with plural optical detectors arranged in relation to the speckle pattern to sense the magnitude and spatial phase of each speckle (on the average). The sampled outputs of the CID detectors are processed to isolate the magnitude and phase information representing the complex optical wavefront of the hologram from irrelevent terms created by the interference process. The detected information may be used for such purposes as imaging, interferometry, matched filtering or correlation.

Electronic holographic apparatus

A novel acoustic vibration sensor and novel acoustic vibration sensing system are described having principal application to hydrophones and operating upon the optical heterodyning principle. The sensor employs a pair of single mode fibers, optically coupled by a path whose length is varied by the acoustic vibrations, and including a partially reflecting discontinuity at the sensitive end of each fiber. Optical signals of one frequency are supplied to one fiber, and of another frequency to the other fiber. Optical signals of the same difference frequency emerge from the 'dry end' of each fiber. When these two emergent signals are photodetected, and the phase or frequency difference is obtained, the acoustic vibration is sensed. The process effectively cancels out noise pickup in the single mode fibers and in other parts of the system, such as laser noise and oscillator instabilities.

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North Syracuse, NY, United States of America

Joseph Lawrence Chovan