Patents by Inventor Herbert J. Shaw
Herbert J. Shaw has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).
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Patent number: 4530603Abstract: A fiber optic sensor comprises a length of optical fiber, forming a loop, and a fiber optic directional coupler for optically closing the loop. The loop and coupler form a resonant cavity for light circulating therethrough. A PZT cylinder, about which the fiber loop is wrapped, is utilized to control the total round trip phase delay of the circulating light, and thus, control the intensity of the optical output signal. The phase delay is adjusted to a point where the optical output signal is at maximum sensitivity to changes in phase. When the fiber loop is exposed to, e.g., acoustic waves, the loop length changes correspondingly, thereby causing the phase delay, and thus, the optical output signal to vary. By detecting variations in output signal intensity, the frequency and intensity of the acoustic waves may be determined. The sensor also includes a feedback system for stabilizing the fiber loop against low frequency thermal drift.Type: GrantFiled: September 29, 1982Date of Patent: July 23, 1985Assignee: The Board of Trustees of Leland Stanford Jr. Univ.Inventors: Herbert J. Shaw, Marvin Chodorow, Loren F. Stokes
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Patent number: 4529312Abstract: A fiber optic rotation sensor, employing detection of the Sagnac phase shift, comprises a single mode fiber forming a loop. The rotation sensor utilizes unpolarized light to provide reciprocal operation. The unpolarized light produces incoherent light wave components which are averaged to zero in the detector. Non-rotationally induced phase shifts between coherent components resolve into vectors equal in magnitude and opposite in phase angle so that the non-reciprocal components of these vectors cancel.The rotation sensor is independent of environmental factors when the phase difference between the waves counterpropagating through the loop is an odd multiple of .pi./2. Accordingly, the sensor includes a phase shifter for biasing such phase difference to .pi./2 to provide a stable operating point when the loop is at rest. Additional compensating means are included to provide stability during rotation.Type: GrantFiled: July 29, 1981Date of Patent: July 16, 1985Assignee: The Board of Trustees of the Leland Stanford Junior UniversityInventors: George A. Pavlath, Herbert J. Shaw
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Patent number: 4530097Abstract: A Brillouin ring laser comprises a fiber optic resonator formed from a loop of fiber optic material and a fiber optic directional coupler for optically closing the loop.Type: GrantFiled: September 29, 1982Date of Patent: July 16, 1985Assignee: The Board of Trustees of the Leland Stanford Junior UniversityInventors: Loren F. Stokes, Herbert J. Shaw, Marvin Chodorow
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Patent number: 4515431Abstract: An optical fiber bidirectional amplifier includes a pair of small diameter optical fibers, arranged in a side-by-side configuration, the first fiber providing a pumping source and the second fiber doped with a material which will lase at the frequency of the signal to be amplified. The signal to be amplified propagates through the second fiber to stimulate emission of coherent light from the lasing material, resulting in amplification of the signal. The refractive indexes of the first and second fibers are substantially identical, but the coupling characteristic provided by the geometrical relationship between the pair of fibers yields a wavelength dependent coupling efficiency. Specifically, the coupling efficiency at the wavelength of the pumping source is relatively high, while the coupling efficiency at the wavelength of the signal to be amplified is relatively low.Type: GrantFiled: August 11, 1982Date of Patent: May 7, 1985Assignee: The Board of Trustees of the Leland Stanford Junior UniversityInventors: Herbert J. Shaw, Marvin Chodorow, Michel J. F. Digonnet
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Patent number: 4493528Abstract: Apparatus and method of manufacture for coupling optical power between two strands of fiber optic material in a given direction of propagation. The coupler employs generally parallel, intersecting strands of fiber optic material having the cladding removed on one side thereof to within a few microns of the fiber cores in the region of intersection to permit light transfer between the strands.Type: GrantFiled: April 11, 1980Date of Patent: January 15, 1985Assignee: Board of Trustees of the Leland Stanford Junior UniversityInventors: Herbert J. Shaw, Ralph A. Bergh
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Patent number: 4479701Abstract: A fiber optic recirculating memory is disclosed which utilizes dual couplers to form a splice-free recirculating memory device from a length of single mode optical fiber forming a loop which acts as a delay line and a second length of single mode optical fiber which provides an input end and an output end for the device. A single signal supplied as an input to the device will result in a series of output signals identical to the input signal, although at smaller, decreasing amplitudes; the invention prevents the first output signal from being substantially larger than the rest of the output signals, thus eliminating the need for protective circuitry on the output end or the rejection of the first output signal.Type: GrantFiled: December 1, 1981Date of Patent: October 30, 1984Assignee: Leland Stanford Junior UniversityInventors: Steven A. Newton, John E. Bowers, Herbert J. Shaw
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Patent number: 4473270Abstract: A fiber optic recirculating memory is disclosed which utilizes a single splice-free single mode optical fiber coupled to itself to form a loop which acts as a delay line. A single signal supplied as an input to the device will result in a series of output signals identical to the input signal, although at smaller, decreasing amplitudes. In addition to being useful as a recirculating memory device for use in a system where data is generated at a rate faster than it can be accepted by a data processor, the invention may be used as a tap filter to pass a selected fundamental frequency and its harmonics, and to attenuate all other frequencies.Type: GrantFiled: October 23, 1981Date of Patent: September 25, 1984Assignee: Leland Stanford Junior UniversityInventor: Herbert J. Shaw
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Patent number: 4469397Abstract: A fiber optic resonator comprises a single strand of optical fiber forming a loop and a fiber optic directional coupler for optically closing the loop. The length of the loop is selected to cooperate with the phase shift of the coupler to provide a resonant cavity, and the coupling constant is selected to provide full or maximum resonance with zero output power.Type: GrantFiled: September 29, 1982Date of Patent: September 4, 1984Assignee: Board of Trustees of the Leland Stanford Junior UniversityInventors: Herbert J. Shaw, Marvin Chodorow, Loren F. Stokes
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Patent number: 4462699Abstract: A transducer for the measurement of temperature incorporates a fiber optic coupler having a coupling efficiency which varies in relation to the index of refraction of a thin layer of index matching liquid, such as index matching oil, placed between the optical fibers of the coupler. Since the index of refraction of the liquid varies predictably with temperature, the coupling efficiency of the transducer may be used to directly measure the temperature of the coupler and its surroundings.Type: GrantFiled: September 10, 1981Date of Patent: July 31, 1984Assignee: Board of Trustees of the Leland Stanford Junior UniversityInventors: Herbert J. Shaw, Michel J. F. Digonnet
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Patent number: 4461574Abstract: An environmentally independent fiber optic rotation sensor having a polarizer or polarization filter interposed between each beam coupler and the beamsplitter of the rotation sensor. The polarizers permit the passing of the polarization of the beams therethrough while rejecting the cross-polarized waves of the beams thereby causing a co-polarized mode of operation to take place. As a result of the co-polarized mode of operation the rotation sensor is unaffected by the surrounding environmental conditions. However, in so doing, the rotation sensor is subject to spurious fringe patterns which take place at the fiber ends. Elimination of these fringe patterns take place at the input side of the rotation sensor rather than at the output side in order to produce satisfactory rotation sensing.Type: GrantFiled: December 18, 1979Date of Patent: July 24, 1984Assignee: The United States of America as represented by the Secretary of the Air ForceInventors: Herbert J. Shaw, Herve J. Arditty
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Patent number: 4461536Abstract: A transducer for the measurement of minute displacements incorporates a fiber optic coupler having a coupling efficiency which varies in relation to the relative position of coupler elements. The transducer may also be used indirectly as an accurate sensor of physical parameters, such as temperature and pressure, through the use of a secondary transducer which provides a displacement proportional to such physical parameter. The outputs from the fiber optic coupler may be compared to provide a measure of the coupling efficiency, and may be monitored by a display which provides a direct measurement of displacement or a secondary physical parameter.Type: GrantFiled: September 10, 1981Date of Patent: July 24, 1984Assignee: Board of Trustees of Leland Stanford Jr. UniversityInventors: Herbert J. Shaw, Michel J. F. Digonnet
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Patent number: 4410275Abstract: Rotation sensor having a loop of fiber optic material in which counter propagating waves are generated with a phase relationship corresponding to the rate at which the loop is rotated. All fiber optic components are employed in the system for directing the light to and from the loop and establishing, maintaining and controlling proper polarization of the light. In one particularly preferred embodiment, the loop and other components are formed on a single strand of fiber optic material which extends continuously through the system.Type: GrantFiled: March 31, 1981Date of Patent: October 18, 1983Assignee: The Board of Trustees of the Leland Stanford Junior UniversityInventors: Herbert J. Shaw, Herve C. Lefevre, Ralph A. Bergh
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Patent number: 4323310Abstract: A fiber optic rotation sensing interferometer based on the Sagnac effect in which mechanical rotation introduces measurable shifts in the phase of optical signals transversing a closed path. The interferometer includes the closed optical path made up of a multi-turn fiber optic loop, a directional coupler or couplers, and an amplifier. A pulse of electromagnetic radiation is fed into the optical path by means of a pulsed electromagnetic source such as a laser and a beam splitter. The beam splitter splits the pulse into two pulses which undergo multiple circulations about the optical path in opposite directions. The directional couplers non-destructively sample the two pulses after each pass therethrough and send the pair of pulse samples to the beam splitter once each circulation. The beam splitter sends these pulse pair samples to a detector and signal processor once each circulation.Type: GrantFiled: December 5, 1979Date of Patent: April 6, 1982Assignee: The United States of America as represented by the Secretary of the Air ForceInventors: Herbert J. Shaw, Marvin Chodorow
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Patent number: 4167120Abstract: A surface acoustic wave bridge for rotation measurement which uses acoustic waves propagated in opposite directions about the circumference of a rotor. The acoustic waves are generated by a transducer adjacent the rotor which is excited by an rf electric field. Clockwise and counterclockwise waves in the surface of the rotor interfere with each other adjacent the transducer to form a bridge system which produces a null when the waves are out of phase. The rf frequency of the electric field is varied to obtain the null and, thus, is a measurement of the rotation rate of the rotor.For the measurement of slow rotation rates two transducers are used to generate the counterrotating acoustic waves in a helical pattern such that the acoustic wave generated by one transducer is received by the other. The outputs of the transducers are detected and provide an approximately linear measurement of slow rotational rates.Type: GrantFiled: May 18, 1978Date of Patent: September 11, 1979Assignee: The United States of America as represented by the Secretary of the NavyInventors: Herbert J. Shaw, Jacques Souquet, Christopher M. Fortunko
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Patent number: 4061040Abstract: A measuring apparatus for determining the rotational velocity of a solid erical or cylindrical object by propagating an acoustic wave through the object. The inward face of the surface of the object is used to reflect the wave, thereby causing it to make multiple transits through the object. Multiple transits provide a large time factor which allows the apparatus to achieve a high degree of sensitivity in measuring small rate changes and low rotation rates.Type: GrantFiled: July 2, 1976Date of Patent: December 6, 1977Assignee: The United States of America as represented by the Secretary of the NavyInventor: Herbert J. Shaw