Exclusive-type Receiver Patents (Class 367/149)
  • Patent number: 4908802
    Abstract: A two-port fiber optic repeater includes means for receiving and restoring command word signals and means for receiving and restoring return data signals. A periodically actuated power supply supplies power to circuitry for sensing valid signal inputs to the repeater. When valid signal inputs are sensed, a main power supply is enabled to supply constant power to signal restoration circuitry. The pulse width of the command word signals are adjusted. The return data signals are restored using a fixed-frequency oscillator and a counter.
    Type: Grant
    Filed: November 30, 1984
    Date of Patent: March 13, 1990
    Assignee: Geosource, Inc.
    Inventors: Donald W. Harvey, Bing-Fai Fung, Donald J. Bacha
  • Patent number: 4893930
    Abstract: A mechanical vibration transducer includes a seismic mass is supported by a plurality of cylindrical silicone rubber mandrels. Each mandrel is wound with a length of optical fiber which has a reflective end and a transmissive end. A case surrounds the assemblage and is connected to the supports. When the case is displaced, the supports change diameter in response to the relative motion between the seismic mass and the case. This change in diameter is translated to a change in length of the optical fiber. By using the fibers as arms of a michelson interferometer, a sensitive instrument responsive to displacing vibrations is obtained. This instrument is energized entirely by light transmitted through optical fiber waveguides and whose information is transmitted to the observor using only light . waves in optical fibers.
    Type: Grant
    Filed: January 25, 1988
    Date of Patent: January 16, 1990
    Assignee: The United States of America as represented by the Secretary of the Navy
    Inventors: Steven L. Garrett, David L. Gardner
  • Patent number: 4882716
    Abstract: An optic fiber hydrophone comprises a wide spectrum optical source, a super-luminescent diode for example, associated with an optic fiber assembly comprising chiefly a side-hole optic fiber, subjected to the field of pressure, forming a sensor, transmitting the optic radiation in the slow and fast modes respectively, and a second fiber, not subjected to the field of pressure, the neutral axes of which are oriented with respect to the neutral axis of the first fiber so that the wave transmitted in slow mode in one fiber is transmitted in fast mode in the other fiber, it being possible to connect these two fibers by a polarization maintaining fiber in the event that the sensor is offset with respect to the source, a polarizing fiber enabling the creation of the interferences, and a radiation detector at the output of the fiber assembly.
    Type: Grant
    Filed: January 24, 1989
    Date of Patent: November 21, 1989
    Assignee: Thomson-CSF
    Inventors: Herve Lefevre, Dominique Rojas, Marc Turpin
  • Patent number: 4875775
    Abstract: An optical instrument is provided which can be configured as a gyro, spectrometer, or other sensor of effects that can influence the transmission of light through a light conduit wherein a beam of light is split and introduced into both ends of an optical fiber which in the gyro case is a fiber-optic coil. Two fixed frequency shifters and two variable frequency shifters, one each at each end of the coil, which are switched on in alternate pairs, are used to adjust any nonreciprocal phase shift caused by rotation of the coil. The beams are mixed backed together and the resultant beam is detected and analyzed by suitable circuitry to provide an output indicative of the angular position, direction of rotation, and angular rate of the motion of the fiber-optic coil as well as any frequency bias and scale factor changes. When configured as a spectrometer, the coil is made insensitive to rotation so that changes are the result of changes in the light source.
    Type: Grant
    Filed: August 20, 1984
    Date of Patent: October 24, 1989
    Assignee: McDonnell Douglas Corporation
    Inventors: Ronald J. Michal, Eric Udd, Richard F. Cahill
  • Patent number: 4825424
    Abstract: A sensing system for sensing acoustic waves, the sensing system comprises one or more sensor elements for use underwater, a reference sensor, and compensation means for compensating noise generated in the sensing system in dependence upon signals provided by the sensor elements and the reference sensor.
    Type: Grant
    Filed: August 20, 1987
    Date of Patent: April 25, 1989
    Assignee: Plessey Overseas Limited
    Inventors: Chris Lamb, Chris Wade
  • Patent number: 4799752
    Abstract: The apparatus according to the invention is all-fiber optic device that produces an output indicative of the gradient of an acoustic wave in water. The device comprises a neutrally buoyant body having a relatively rigid outer case. When it is submerged in water, the motion of the case is the same as that of a water particle in the same vicinity. A fiber optic linear accelerometer produces a signal proportional to the component of acceleration.
    Type: Grant
    Filed: September 21, 1987
    Date of Patent: January 24, 1989
    Assignee: Litton Systems, Inc.
    Inventor: Edward F. Carome
  • Patent number: 4799202
    Abstract: A cylindrical interferometric hydrophone having an axial hollow free-flooded volume includes an outer fiber wrap for a sensor leg and an inner fiber wrap for a reference leg. Both inner and outer fiber wraps are wound on elastomers and exposed to seawater for sensing acoustic signals. In operation an increased pressure shortens the outer wrap and lengthens the inner wrap. This use of both the sensor and the reference legs to detect signals gives increased sensitivity.
    Type: Grant
    Filed: September 27, 1982
    Date of Patent: January 17, 1989
    Assignee: The United States of America as represented by the Secretary of the Navy
    Inventor: Gerald L. Assard
  • Patent number: 4792931
    Abstract: A detector for detecting the acceleration, the velocity or the displacement of a point is described. The detector includes a light source, at least two photoelectric elements spaced apart from each other over a predetermined distance and a focusing optical system disposed between the light source and the photoelectric elements; the combination being particularly suited for use as an optical seismic detector for detecting and mapping an underground stratum structure.
    Type: Grant
    Filed: September 23, 1986
    Date of Patent: December 20, 1988
    Assignee: Schlumberger Technology Corporation
    Inventors: Katsuhiko Nishida, Mansanari Shindo, Masaharu Suzuki, Masamichi Kondo
  • Patent number: 4751690
    Abstract: A fiber optic interferometric hydrophone is based on the change in optic path length of optic fibers bonded to both sides of a bending beam which acts as an acoustically sensitive diaphragm.The bending beam is segmented into an even number of segments, acoustic windows are arranged such that opposite sides of the beam see the acoustic field in adjacent segments, and the optic fibers cross from one side of the beam to the other to maintain the phase of strain signal for the two fibers, one on each side, along the full length of the bending beam. The fringe sensitivity of the interferometer is multiplied by two since both interferometer legs are strained by the acoustic field, and of opposite sign, and further multiplied by the number of segments compared to a single simple beam bender of the dimensions of one segment.
    Type: Grant
    Filed: May 12, 1986
    Date of Patent: June 14, 1988
    Assignee: Gould Inc.
    Inventor: Helmut H. A. Krueger
  • Patent number: 4743113
    Abstract: A radiation source launches a radiant pulse of a desired width into a plurality of parallel-coupled optical sensors for modulation by a quantity to be measured. The modulated output from any two sensors taken in all combinations are interferometrically combined to generate a series of time-separated interference patterns. The interference patterns are probed by a photodetector and vectorially combined to provide the vector gradient of the quantity under measurement.
    Type: Grant
    Filed: August 29, 1985
    Date of Patent: May 10, 1988
    Assignee: Western Atlas International, Inc.
    Inventor: Paul Jubinski
  • Patent number: 4725995
    Abstract: A cartridge retention system includes a cartridge carrying electronic, compressed gas or other components which has a spring-loaded button at one end and which is removably mounted in the breech of an adapter module connected either in a streamer section or between opposing ends of adjacent streamer sections of a towed array. The cartridge is demountably retained within the adapter by providing an adapter housing with a breech which is somewhat longer than the cartridge, and by providing the housing with an overlying two part shell which is rotatable about the housing, with one of the shell parts containing an aperture to accommodate cartridge insertion and with both parts containing an internal circumferential groove adapted to coact with the spring-loaded button on the cartridge to move the cartridge from one end of the breech to the other end upon rotation of the shell.
    Type: Grant
    Filed: March 5, 1984
    Date of Patent: February 16, 1988
    Assignee: The Laitram Corporation
    Inventor: John T. Fowler
  • Patent number: 4688200
    Abstract: An optical sound source signature transducer system for use in marine seismic exploration in which coherent radiation from a laser is coupled to unequal length optical paths exposed to modulation by the acoustic energy wave generated by the sound source. The reflected beams from the paths are crosscoupled to generate interference fringes in two output beams out of phase with each other. The fringes in one output beam are counted in an up/down counter to determine the magnitude of the pressure as a function of time. The direction of the pressure change is determined by examination of the phase relationship between the fringes in the output beams. Peaks and valleys in the pressure are detected as phase reversals between the fringes in the output beams be detecting the beginning and end of a fringe in one beam without detecting the beginning or end of a fringe in the other beam therebetween.
    Type: Grant
    Filed: September 18, 1985
    Date of Patent: August 18, 1987
    Assignee: Western Geophysical Company of America
    Inventors: Thomas J. Poorman, David Grissom, Edward F. Carome
  • Patent number: 4649529
    Abstract: A time division multiplexing, fiber optic data gathering system, including two or more sensors formed on an optical fiber, and a phase sensitive detector. Each sensor includes two reflectors separated by a section of the fiber having length L. Each reflector may be activated so that when an interrogating light signal propagates in a first direction past the activated reflector, a portion of the interrogating light signal will be reflected back into a direction opposite the first direction. Each reflector may also be deactivated so that the interrogating signal may propagate unhindered past the deactivated reflector. Variations in the optical path length between the reflectors of a sensor, due to changes in an external parameter of interest, will cause phase modulations that are extracted in the phase sensitive detector by homodyne or heterodyne techniques.
    Type: Grant
    Filed: December 2, 1985
    Date of Patent: March 10, 1987
    Assignee: Exxon Production Research Co.
    Inventor: Kenneth Avicola
  • Patent number: 4649528
    Abstract: An apparatus for the detection of the arrival and for the determination of the velocity of disturbances such as shock-wave fronts and/or projectiles. Optical pins using fluid-filled microballoons as the light source and an optical fiber as a link to a photodetector have been used to investigate shock-waves and projectiles. A microballoon filled with a noble gas is affixed to one end of a fiber-optic cable, and the other end of the cable is attached to a high-speed streak camera. As the shock-front or projectile compresses the microballoon, the gas inside is heated and compressed producing a bright flash of light. The flash of light is transmitted via the optic cable to the streak camera where it is recorded. One image-converter streak camera is capable of recording information from more than 100 microballoon-cable combinations simultaneously.
    Type: Grant
    Filed: October 18, 1983
    Date of Patent: March 10, 1987
    Assignee: Robert F. Benjamin
    Inventor: Robert F. Benjamin
  • Patent number: 4648082
    Abstract: A pressure gradient sensor is disclosed for optically sensing the direction and magnitude of an acoustic wave propagating through a fluid. Each sensor consists generally of at least three fiber-optic displacement sensors disposed within a circular array oriented perpendicular to the longitudinal axis of a streamer. Each sensor phase-modulates a coherent light signal indicative of the water pressure sensed outside the streamer. The output of the signals include a component due to transient pressure waves and a component due to hydrostatic pressure differences between the sensors.
    Type: Grant
    Filed: March 4, 1985
    Date of Patent: March 3, 1987
    Assignee: Western Geophysical Company of America
    Inventor: Carl H. Savit
  • Patent number: 4648083
    Abstract: A method and apparatus for remotely activating and analyzing fiber optic ed and conformal sensor arrays using fiber optic transmission and reception with multiplexed input and output signals using optical wavelength division, electronic frequency division, or both.
    Type: Grant
    Filed: January 3, 1985
    Date of Patent: March 3, 1987
    Assignee: The United States of America as represented by the Secretary of the Navy
    Inventor: Thomas G. Giallorenzi
  • Patent number: 4631711
    Abstract: A cartridge carrying electronic or other components is removably mounted in the breech of an adaptor module connected either in a streamer section or between opposing ends of adjacent streamer sections of a towed array. The adapter module is provided with channels for loosely guiding all but one strain member, one strain member being clamped to the module, with the longitudinal axis of the module breech being established by the longitudinal axis of the clamped strain member such that alignment of the cartridge is uniquely keyed to the single clamped strain member, the loose mounting of the unclamped strain members preventing differential forces being applied to the adapter module. In one embodiment, a spring-loaded pin and shuttle connector arrangement severs connection for an empty breech and provides for both point contact to an inserted cartridge and relatively long leakage paths so that any entrained sea water will not short out the adapter module or connector system.
    Type: Grant
    Filed: November 24, 1982
    Date of Patent: December 23, 1986
    Assignee: The Laitram Corporation
    Inventor: John T. Fowler
  • Patent number: 4599711
    Abstract: An improved bifurcated multi-lever fiber optic transducer comprising one ht transmitting fiber and two receive fibers having different core diameters separated at one end and combined at the common distal end in the vicinity of a reflective surface parallel to the fiber end plane which is sensitive to axial motion caused by minute pressure changes, either in air or water, such that any displacement of the reflector from equilibrium will increase or decrease the illuminated areas of the two receive fibers which can be used to generate a processed output signal proportional to this motion. The resulting probe is of minimal diameter, has significantly improved sensitivity and produces an output independent of power variations at the input.
    Type: Grant
    Filed: October 29, 1984
    Date of Patent: July 8, 1986
    Assignee: The United States of America as represented by the Secretary of the Navy
    Inventor: Frank W. Cuomo
  • Patent number: 4593385
    Abstract: An optoacoustic hydrophone for detection of acoustic waves in a fluid such as sea water. The hydrophone includes an optical waveguide comprising a fiber optic input lead, a fiber optic sensor, and a fiber optic exit lead, an optical subassembly and a signal processor. A coherent light beam generated by the optical subassembly is transmitted through the input lead and the sensor which is disposed in the fluid. Acoustic waves in the fluid modulate the index of refraction of the fiber optic sensor thereby modulating the transmitted light beam. The modulated light beam is directed through the fiber optic exit lead to a focus on one of two photodetectors. The other photodetector is oriented for receipt of light reflected from a partially reflective mirror disposed between the input fiber optic lead and the fiber optic sensor. The two light beams impinging on respective photodetector are combined with unmodulated light beams of slightly different frequencies to produce an interference pattern at each photodetector.
    Type: Grant
    Filed: May 19, 1983
    Date of Patent: June 3, 1986
    Assignee: The Charles Stark Draper Laboratory
    Inventor: Jacques R. Chamuel
  • Patent number: 4589285
    Abstract: An optical telemetric system for use in a borehole consists of a bidirectional optical fiber to which are coupled a plurality of acousto-optical seismic sensors. The sensors consist of an optical cavity that becomes resonant at certain wavelengths depending upon parameters of cavity length and index of refraction. Those parameters are capable of being modified on the basis of static and dynamic pressure differences within the borehole. A swept-wavelength laser chirp pulse is launched into the bidirectional optical fiber. The static pressure at each sensor establishes a resonant wavelength that serves as a carrier signal. Dynamic pressure changes due to seismic waves, modulate the carrier signal. The modulated carrier signals from each sensor are reradiated through the bidirectional optical fiber in a wavelength-division multiplexed format. The multiplexed signals are received by and demultiplexed by a suitable signal receiving apparatus.
    Type: Grant
    Filed: November 5, 1984
    Date of Patent: May 20, 1986
    Assignee: Western Geophysical Co. of America
    Inventor: Carl H. Savit
  • Patent number: 4570248
    Abstract: An interferometer inhibits a received low frequency acoustic signal that is elow the pass band of interest from appearing in the output. The interferometer has a conventional optical hydrophone in the signal leg to sense both the high and low frequencies of an acoustic signal. The reference leg has means for accepting a low frequency acoustic signal to modulate the coherent light path length while inhibiting the desired high frequency signal. On recombining the signals from both the signal and reference legs the low frequency signal appearing in both legs is canceled and only the high frequency signal appearing in the signal leg reaches the output. In an alternate embodiment the reference leg mandrel is placed internal to the sensor mandrel and provides a low frequency compensation chamber.
    Type: Grant
    Filed: September 27, 1982
    Date of Patent: February 11, 1986
    Assignee: United States of America as represented by the Secretary of the Navy
    Inventor: Gerald L. Assard
  • Patent number: 4547869
    Abstract: A hydrophone streamer that includes several arrays of optical fiber pressure sensors. Each array consists of at least three sensors symmetrically disposed around the inside of the streamer skin to form a vertically-disposed array. Each sensor modulates a coherent light beam in accordance with the instantaneous ambient water pressure. The output signals of the sensors include an AC component due to seismic waves and a DC component due to hydrostatic pressure difference between the sensors of an array. Means are provided to resolve the AC and DC components to determine the arrival direction of the received seismic waves.
    Type: Grant
    Filed: April 4, 1983
    Date of Patent: October 15, 1985
    Assignee: Western Geophysical Company of America
    Inventor: Carl H. Savit
  • Patent number: 4546458
    Abstract: A method of modulating the output of a solid state diode laser by directly straining the laser chip. The chip is mechanically coupled to a transducer such as a piezoelectric crystal in such a manner that a dimensional variation in the transducer is translated into a corresponding variation in the chip. It is contemplated that the modulated output will have application in communication systems and in particular a hydrophone system.
    Type: Grant
    Filed: May 17, 1982
    Date of Patent: October 8, 1985
    Inventors: Paolo G. Cielo, Garfield W. McMahon
  • Patent number: 4536861
    Abstract: The invention relates to a monomodal optical fibre hydrophone operating by elastooptical effect, which has an interferometer structure comprising a measuring arm, in which is arranged a very long monomodal optical fibre immersed in the interaction medium in which propagates the soundwave. A phase displacement is induced by an elastooptical effect on the soundwave propagating in the fibre, by a soundwave producing an acoustic pressure field in said medium. A reference arm establishes a reference optical path and the phase displacement, linked with the sound wave, is detected by interferometry between the two optical waves coming from these two arms. This two-armed interferometer is terminated by a photorefractive medium used as an interactive reflector in accordance with the four-wave interferometry principle.
    Type: Grant
    Filed: February 27, 1984
    Date of Patent: August 20, 1985
    Assignee: Thomson-CSF
    Inventors: Philippe Graindorge, Herve Arditty
  • Patent number: 4530078
    Abstract: A microbending fiber optic acoustic sensor. A point hydrophone according to a first preferred embodiment of the present Invention includes two opposed pistons which are subjected to an acoustic pressure wave. In response to the pressure wave, the opposed pistons push a pair of deformer plates against an optical fiber to deform the fiber thereby intensity modulating an optical signal passing through the fiber. An extended hydrophone according to a second preferred embodiment of the present Invention includes an optical fiber wound in a helical groove formed in a cylindrical surface. A plurality of parallel axial slots are located in a spaced-apart relationship to each other at positions about the cylindrical surface and are oriented in parallel with the axis of the cylindrical surface. Each axial slot intersects with the helical groove at a plurality of locations and has a depth greater than the depth of the groove.
    Type: Grant
    Filed: June 11, 1982
    Date of Patent: July 16, 1985
    Inventors: Nicholas Lagakos, W. James Trott
  • Patent number: 4525818
    Abstract: An optical fiber hydrophone system in which a single optical fiber is used for all of the acoustical sensors in the system. A signal source and detector provides an optical signal in selected form, such as continuous or pulsed and detects and extracts an identifiable output signal. Each sensor is in the form of a sensing portion of the single optical fiber. Each sensing portion includes two optical reflectors separated one from another by a predetermined length of said optical fiber. Variations in acoustical pressure incident on the sensing portion causes a change in the predetermined length. This causes reflected portions of the optical signal to interfere with one another. Such interference is detectable for extraction of the identifiable output signal. In one form each sensing portion has two terminal branches of a mechanically deformable material, deformable in response to the fluctuations in acoustical pressure.
    Type: Grant
    Filed: July 28, 1982
    Date of Patent: June 25, 1985
    Assignee: Her Majesty the Queen in right of Canada, as represented by Minister of National Defence of Her Majesty's Canadian Government
    Inventors: Paolo G. Cielo, Garfield W. McMahon
  • Patent number: 4519252
    Abstract: An acoustic sensor with ambient pressure and temperature compensation having a photoelastic element positioned between a diaphragm and a support beam. Thin layers of oil between the photoelastic material and both the diaphragm and support beam prevent surface stress of the photoelastic element due to slowly varying pressures while surface stresses are caused thereon by relatively rapid pressure variations.
    Type: Grant
    Filed: March 21, 1983
    Date of Patent: May 28, 1985
    Assignee: Sperry Corporation
    Inventor: Donald H. McMahon
  • Patent number: 4518857
    Abstract: A pressure and temperature compensated acoustic transducer utilizing a pressure sensitive birefringent element coupled between a flexible diaphragm sealing the transducer and an internal variable rigid diaphragm that forms two internal chambers. Relatively rapid variation in pressure applied to the birefrigent element cause fluctuations in the phase difference between orthogonal components of a polarized light beam traversing the photo-elastic material. Detections of this phase difference variation provides signals representative of incident acoustic signals. Provision for the transfer of liquid filling the chambers permits the equalization between the two chambers of slowly varying internal pressures caused by changes in external ambient pressure and temperature.
    Type: Grant
    Filed: March 7, 1983
    Date of Patent: May 21, 1985
    Assignee: Sperry Corporation
    Inventors: Donald H. McMahon, William B. Spillman, Jr.
  • Patent number: 4500979
    Abstract: A spring-suspended mass has top and bottom reflectors. A laser light beam is divided into separate beams that are reflected from the top and bottom reflectors into photo detectors. At the photo detectors, a reference beam from the same laser is recombined with the two reflected beams to produce two interference fringe patterns in response to seismic disturbances of the mass. A count of the number of fringes and fractions thereof that are detected over a unit time interval is proportional to velocity of the mass in terms of the wavelength of the laser beam. The phase difference between the two interference fringe patterns is a measure of polarity of the seismic disturbances.
    Type: Grant
    Filed: September 16, 1981
    Date of Patent: February 19, 1985
    Assignee: Western Geophysical Co of America
    Inventor: Gary L. Scott
  • Patent number: 4486657
    Abstract: A fiber optic acoustic sensing system for tracking a phase shift linearly over a wide range thereby allowing accurate tracking in the presence of temperature induced phase flucuation. In one embodiment, light from a laser is split and coupled into both legs of a fiber interferometer. One leg is phase modulated by the acoustic signal while the other leg is phase modulated by a first and a second piezoelectric cylinder modulators. The second modulator is driven at .omega..sub.m to effectively shift the acoustic information up in frequency into the sidebands of the carrier .omega..sub.m. The light signals in the two legs are combined, detected, cross-correlated with the carrier .omega..sub.m to produce an error signal, and then low pass filtered. This filtered error signal is fed back to control the first modulator. The first modulator keeps the interferometer locked in phase by effectively cancelling out the phase produced by temperature and acoustic pressure flucuations.
    Type: Grant
    Filed: May 27, 1982
    Date of Patent: December 4, 1984
    Assignee: The United States of America as represented by the Secretary of the Navy
    Inventor: Ira J. Bush
  • Patent number: 4471474
    Abstract: Apparatus is provided for detecting the presence of acoustic signals which includes a laser source, and a detector coupled to opposite end of an acousto-optic transducer. The transducer may employ fiber optic waveguides, etched to allow evanescent coupling therebetween, and disposed within a flexible housing. Integrated and planar optic transducers are provided in various forms employing two integrated optic waveguide channels, two planar waveguides, or a planar waveguide and absorber combination. Each configuration is disposed within a flexible housing and the waveguides are separated from each other by a predetermined distance. Any flexing of the housing is transformed into a displacement of the waveguides relative to one another. The coupling between the waveguides is a very sensitive function of distance, and hence detection of variations in the energy coupled by the waveguides provides an indication of the presence of the acoustic signals.
    Type: Grant
    Filed: September 13, 1982
    Date of Patent: September 11, 1984
    Assignee: Hughes Aircraft Company
    Inventor: Joseph N. Fields
  • Patent number: 4458343
    Abstract: The invention relates to hydrophones which require liquid backing of the sensing plate, and more particularly, to compliance enhancing means for use in such hydrophones. In a practical embodiment, in which a compliant sensing plate in the form of a thin diaphragm is employed, liquid backing of the sensing plate is provided to balance the hydrostatic pressure across the sensing plate. To increase the compliance of the hydrophone, reduced by the presence of the backing oil, and to do so in a linear manner, a bellows is introduced into the backing chamber having the desired compliance and pressure rating. The invention is applicable to hydrophones having either compliant or stiff sensing plates. An improvement in hydrophone linearity and sensitivity is obtainable over a significant range of hydrostatic pressures.
    Type: Grant
    Filed: December 7, 1981
    Date of Patent: July 3, 1984
    Assignee: General Electric Company
    Inventors: Stephen W. Tehon, Evelyn H. Monsay
  • Patent number: 4451151
    Abstract: An interaction medium in which a photoinduced phase grating has been permanently recorded beforehand is coupled to the two ends of a monomode waveguide. A first wave which is a pulse travels through said waveguide and interferes with a second pumping wave in order to permit energy transfer from the second pumping wave to the first wave.
    Type: Grant
    Filed: February 23, 1982
    Date of Patent: May 29, 1984
    Assignee: Thomson-CSF
    Inventor: Jean-Pierre Huignard
  • Patent number: 4450541
    Abstract: An optical grating hydrophone employs a dual grating construction and two pairs of optical fibers to provide a reliable output signal without the need for mechanically adjusting the system bias. A bias compensation circuit selects the output signal to be received based upon the output signals from the two optical cable pairs.
    Type: Grant
    Filed: December 31, 1981
    Date of Patent: May 22, 1984
    Assignee: General Electric Company
    Inventor: Byron W. Tietjen
  • Patent number: 4449211
    Abstract: A plurality of transducers, closely conforming to the surface of a low-drag ose, are baffle mounted in close pack configurations to eliminate grating lobes. The baffle assembly is mounted outside a pressure hull within a thin acoustically transparent fairing. A plurality of pressure compensators also attach outside the pressure hull. The cavity between pressure hull and fairing is filled with pressure compensating acoustic fluid. Larger portions of unused volume are first filled with a syntactic foam to minimize the amount of fluid required. The pressure compensators balance fluid pressure against external sea pressure to prevent fairing collapse. This array maximizes available nearby internal nose volume thus allowing beamforming electronics to be located within the pressure hull in close proximity to the array elements, connecting thereto via a plurality of short coaxial cables.
    Type: Grant
    Filed: July 6, 1982
    Date of Patent: May 15, 1984
    Assignee: The United States of America as represented by the Secretary of the Navy
    Inventors: Richard L. Schmidt, Edmund J. Sullivan, Bernard J. Myers, Edward G. Liszka
  • Patent number: 4449210
    Abstract: Apparatus is provided including a light source, a transducer and a detector, which is capable of detecting applied acoustic signals. The transducer employs first and second ridged members which have parallel rippled surfaces which contact opposite sides of a fiber optic waveguide. Each rippled surface has a different predetermined ripple pitch which provides for variable sensitivity along one dimension of the transducer. Modulation of the position of the ridged members relative to one another by means of applied acoustic signals causes microbend attenuation of light transmitted through the waveguide. The modulation of the light provides an indication of the presence of the acoustic signals. The variation in dimensional sensitivity provided by the transducer allows for a determination of the direction of arrival of the acoustic signals. Appropriate selection of pitch and pitch ratio of the two rippled surfaces provides any desired spatial sensitivity distribution of the hydrophone.
    Type: Grant
    Filed: December 21, 1981
    Date of Patent: May 15, 1984
    Assignee: Hughes Aircraft Company
    Inventor: Jon H. Myer
  • Patent number: 4446543
    Abstract: A hydrophone remotely senses impinging acoustic energy. Light output from a laser is split and launched into a single-mode fiber which transmits it to an optical resonator at its end. The resonator is made up of a fixed fiber end having a dielectric coating and a movable mirror which is displaced in response to an incident acoustic signal. The acoustic signal displaces the mirror so that mirror movement modulates the intensity of the reflected beam which is transmitted back through the single-mode fiber and received at a detector. The frequency and magnitude of the reflected beam yield acoustic signal information.
    Type: Grant
    Filed: July 2, 1979
    Date of Patent: May 1, 1984
    Assignee: The United States of America as represented by the Secretary of the Navy
    Inventors: Matthew N. McLandrich, Donald J. Albares
  • Patent number: 4436425
    Abstract: A test signal waveform detector that includes a fiber optic interferometer wherein the phase difference of the two parts of a split laser beam is modulated by the waveform of a sinusoidal test signal which is to be detected and by the waveform of a sinusoidal reference signal, and the two parts of the split beam are recombined and mixed on the face of a photodetector. A signal conversion circuit converts the ac signal produced by the photodetector to another ac signal that carries the test signal information as an equivalent frequency modulation, and a demodulator extracts the test signal information from the latter ac signal.
    Type: Grant
    Filed: March 29, 1982
    Date of Patent: March 13, 1984
    Assignee: The United States of America as represented by the Secretary of the Navy
    Inventor: James H. Cole
  • Patent number: 4422167
    Abstract: A wide-area acousto-optic hydrophone which uses signal and reference laser beams together with interferometric methods for detecting underwater acoustic signals. The signal beam is distributed across the wide sensing area of the hydrophone using beam folding techniques while being directly transmitted through a sensing chamber filled with an optically transparent bulk material, the refractive index of which varies with the incident acoustic pressure thereby modulating the signal beam. Concurrently, a reference beam of equal length and folded in an identical pattern is directly passed through an adjacent chamber filled with the same bulk material. A microhole joins the two chambers, to expose the reference beam to the same static pressure and temperature fluctuations as the signal beam thus serving as a low pass filter.
    Type: Grant
    Filed: June 25, 1981
    Date of Patent: December 20, 1983
    Assignee: The United States of America as represented by the Secretary of the Navy
    Inventor: Peter Shajenko
  • Patent number: 4400805
    Abstract: Disclosed is an acoustic transducer which includes a pressure tight vessel with a window in the vessel which is transparent to acoustic wave energy. A gas is disposed within the vessel, while an electromechanical transducer is located within the vessel at an antinode for a resonant wave of the gas. A port communicates with the interior of the vessel, with a pressure control coupled to the port and to a source of the gas for controlling the pressure of the fluid within the vessel.
    Type: Grant
    Filed: April 27, 1981
    Date of Patent: August 23, 1983
    Assignee: Rockwell International Corporation
    Inventor: Harry Nadler
  • Patent number: 4399526
    Abstract: An acoustic array for use at high hydrostatic pressures comprises an acouc isolation baffle positioned adjacent to the hull; an intermediate acoustic conditioning module supported over the isolation baffle; and an outer layer containing a plurality of hydrophone units. The acoustic isolation baffle comprises alternating layers of rigid and compliant materials bonded together in sandwich fashion, wherein the compliant layer is provided with a regular pattern of air cells. In adjoining compliant layers the pattern of air cells is translated relative to each other so that the load bearing walls of one compliant layer overlap the open cell regions of the adjacent compliant layer with only a rigid layer disposed therebetween. The acoustic conditioning module comprises spaced coverplates with spacer elements extending therebetween to form a plurality of chambers which contain viscoelastic damping elements bonded to the outer coverplate.
    Type: Grant
    Filed: January 27, 1981
    Date of Patent: August 16, 1983
    Assignee: The United States of America as represented by the Secretary of the Navy
    Inventor: John J. Eynck
  • Patent number: 4390976
    Abstract: An underwater acoustic array comprises an acoustic skirt baffle positioned djacent to a hull surface for reducing the transmission of shipboard noise; an acoustic conditioning module positioned over the acoustic skirt baffle; and an outer layer secured to the acoustic conditioning module and containing a plurality of hydrophone units.The acoustic conditioning module comprises inner and outer spaced coverplates; a plurality of spacer elements extending between the coverplates to form a plurality of closed chambers therebetween; and "tuned" viscoelastic damping elements secured to the outer coverplate.
    Type: Grant
    Filed: January 27, 1981
    Date of Patent: June 28, 1983
    Assignee: The United States of America as represented by the Secretary of the Navy
    Inventor: John J. Eynck
  • Patent number: 4375680
    Abstract: A light source is operated near its threshhold and its output is split and sent in opposite direction about a fiber optic coil which is exposed to acoustic energy. The recombined light out of the coil is modulated at acoustic frequency. The modulated light can be fed back to the light source which responds to the modulation with large amplitude variations which are sent to a detector for conversion into an electrical signal representative of the acoustic energy. Alternatively, the light beam may be directed from the fiber coil to the detector directly. The sensors can include components for rejecting noise at frequencies not of interest and a plurality of similar sensors can be formed in an array to obtain directional information or increased sensitivity.
    Type: Grant
    Filed: January 16, 1981
    Date of Patent: March 1, 1983
    Assignee: McDonnell Douglas Corporation
    Inventors: Richard F. Cahill, Eric Udd
  • Patent number: 4363114
    Abstract: An optical system for frequency-modulation heterodyne detection of an acoustic pressure wave signal. An optical beam is directed into a Bragg cell outside of the fluid medium in which acoustic signals are to be detected. The Bragg cell modulates the incident beam such that two beams of different frequency exit the cell. The two beams are directed into an input optical fiber and the resultant combined beam is transmitted over a desired distance to a fiber optic transducer disposed in the fluid medium. The transducer includes two coiled optical fibers, a reference fiber and a signal fiber, each of which has a different sensitivity to incident acoustic pressure wave signals. The transmitted beam is directed from the input optical fiber through a power divider which splits the beam into two equal parts, one part passing through the reference fiber, the other part passing through the signal fiber. A filter in the signal fiber transmits only a fraction of the light at one of the two frequencies.
    Type: Grant
    Filed: January 21, 1981
    Date of Patent: December 7, 1982
    Assignee: The United States of America as represented by the Secretary of the Navy
    Inventors: Joseph A. Bucaro, James H. Cole, Henry D. Dardy
  • Patent number: 4360247
    Abstract: An apparatus is disclosed for optically sensing pressure using evanescent wave coupling between two fiber optics. A support base with a channel holds the two waveguides, one on top of the other, with the portion of the waveguide having the cladding material removed in the channel. An upper member having a diaphragm is attached to the support base. The diaphragm has a pedestal attached that is in slight contact with one of the waveguides. When pressure is exerted upon the diaphragm, the waveguides are forced closer together thus affecting the amount of evanescent coupling therebetween.
    Type: Grant
    Filed: January 19, 1981
    Date of Patent: November 23, 1982
    Assignee: Gould Inc.
    Inventor: J. Donald Beasley
  • Patent number: 4322829
    Abstract: A mass is attached between light reflective ends of a pair of rectilinearly aligned optic fibers and maintained in such position with the fibers under a slight tension. The pair of fibers comprise a portion of two arms of a Mach Zehnder or Michelson interferometer so that an acceleration along the longitudinal axis of the rectilinearly aligned optic fibers increases the length of one of the pair of fibers and shortens the length of the other, whereby electromagnetic rays traveling in the pair of fibers, travel different distances resulting in a phase shift which phase shift is directly proportional to the force applied to the fibers by the mass and therefore directly proportional to the acceleration. Accelerations in directions perpendicular to the longitudinal axes of the fibers cause equal phase shifts in each arm and therefore would not be detected. Thermal expansion of the fibers and acoustical noises should also balance out.
    Type: Grant
    Filed: September 11, 1980
    Date of Patent: March 30, 1982
    Assignee: Dynamic Systems, Inc.
    Inventors: Charles M. Davis, Jr., Thomas G. Giallorenzi
  • Patent number: 4320475
    Abstract: The hydrophone has an interferometer structure incorporating a measuring arm in which is provided a very long monomodal optical fibre immersed in the interaction medium in which is propagated the acoustic wave. A phase displacement is induced on the optical wave by the elastooptical effect and said wave is propagated in the fibre by the acoustic wave which creates an acoustic pressure field in the medium. A reference arm establishes a reference optical path and the phase displacement linked with the acoustic wave is detected by interferometry between the two optical waves emerging from the two arms. The optical connections between the source, the optical fibre immersed in the interaction medium, the reference arm and the detector being provided in guided optics in a compact structure.
    Type: Grant
    Filed: June 26, 1980
    Date of Patent: March 16, 1982
    Assignee: Thomson-CSF
    Inventors: Pierre Leclerc, Jean-Pierre Huignard, Michel Papuchon, Claude Puech
  • Patent number: 4315324
    Abstract: Serving as a hydrophone in the lower unit of the sonobuoy, two surface acoustic wave resonators for determining the resonant frequency of two independent oscillators are also used to sense pressure and thus sound. The outputs of the two resonators are mixed and then passed through a low pass filter to provide a low frequency hydrophone output signal and to remove temperature induced signal distortion. A line driver and low cost twin lead transmission line provides the signal to the upper floatation electronic unit of the sonobuoy for conversion to the desired RF carrier frequency. In a single-channel sonobuoy, this signal is multiplied and amplified for transmission to a distant receiver. In a multi-channel sonobuoy, this signal acts as a reference frequency for the frequency synthesizer section of the sonobuoy transmitter.
    Type: Grant
    Filed: September 11, 1980
    Date of Patent: February 9, 1982
    Assignee: The United States of America as represented by the Secretary of the Navy
    Inventors: Michael T. Junod, Albert M. Bates
  • Patent number: 4313185
    Abstract: 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.
    Type: Grant
    Filed: December 31, 1979
    Date of Patent: January 26, 1982
    Assignee: General Electric Company
    Inventor: Joseph L. Chovan
  • Patent number: H280
    Abstract: A connector assembly such that when a first half of the connector receives a second half, a vent hole is defined therethrough. With the second half disconnected and a third half coupled to the first half, the vent hole is sealed.
    Type: Grant
    Filed: July 31, 1986
    Date of Patent: June 2, 1987
    Inventor: Ben B. Thigpen