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公开(公告)号：CA2306681C
公开(公告)日：2005-03-22
申请号：CA2306681
申请日：2000-04-26
Applicant: LITTON SYSTEMS INC
Inventor： HALL DAVID B
Abstract: Quadrature signals Q and in-phase signals I output from a pathlength mismatched interferometric sensor array (10) are normalized by sampling the signals to obtain a first set of values Q k = Q0B k sin .PHI.k corresponding to the sine of the phase shift and a second set of values I k = I0B k cos .PHI.k corresponding to the cosine of the phase shift where k is a running index of the set of consecutive samples of Q and I. A quantity DQ k = (see formula I) is calculated for the quadrature signals; and a quantity DI k = (see formula II ) is calculated for the in-phase signals, where u(k) and s(k) are parameters used to determine indices that select specific sampled signals and k is a running index of the set of consecutive samples of Q and I. The normalization factor is th en calculated as the ratio R = (see formula III) where Q N = (see formula IV) a nd I N = (see formula V).
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公开(公告)号：DE69914981T2
公开(公告)日：2004-12-09
申请号：DE69914981
申请日：1999-07-28
Applicant: LITTON SYSTEMS INC
Inventor： HALL DAVID B , FREDERICK DONALD A , FERSHT SAMUEL N
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公开(公告)号：CA2230039C
公开(公告)日：2004-11-23
申请号：CA2230039
申请日：1998-02-19
Applicant: LITTON SYSTEMS INC
Inventor： HALL DAVID B
Abstract: A pressure sensing system employs a plurality of pulsed, single- wavelength optical signal sources, each emitting a distinct wavelength, whereby a multiplexed incident beam is generated. The incident beam is split into a first portion directed to first photodetector means that generate a reference signal for each wavelength, and a second portion that interrogates one or more Fabry-Perot pressure sensors. The interrogation beam portion is phase-modulated by gap width variations in the sensor(s), and is transmitted to second photodetector means that generate a measured intensity signal for each wavelength. For each wavelength, the ratio of the measured intensity signal to the reference intensity signal is taken, and yields two terms, one of which is an interference term that is proportional to the cosine of the Fabry-Perot phase shift angle .phi., which is a function of the gap width. By choosing wavelengths that are in quadrature relationship for a nominal Fabry- Perot gap width, the algebraic differences can be taken among the ratio s to yield two expressions proportional, respectively, to the cosine and sine of the phase shift angle .phi.. An arctangent calculation is used to obtain the measure of .phi., which is proportional to the gap width, which, in turn, is a known function of the pressure applied to the sensor. The optical sources may be pulsed sequentially to provide a time division- multiplexed incident beam, or simultaneously to provide a wavelength division-multiplexed incident beam.
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公开(公告)号：NO20013609D0
公开(公告)日：2001-07-20
申请号：NO20013609
申请日：2001-07-20
Applicant: LITTON SYSTEMS INC
Inventor： GOLDNER ERIC LEE , TWEEDY MICHAEL J , FERSHT SAMUEL N , HALL DAVID B
IPC: G01H20060101 , G01H9/00 , H04R1/46 , G01H
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公开(公告)号：AU2573101A
公开(公告)日：2001-06-06
申请号：AU2573101
申请日：2000-10-26
Applicant: LITTON SYSTEMS INC
Inventor： HALL DAVID B
Abstract: An electromechanical sensor produces an electrical signal in response to a change in a physical parameter being monitored by the sensor. An optical phase modulator is arranged such that electrical signals from the electromechanical sensor cause a phase change in optical signals propagating in the two legs of the interferometer. The phase change is obtained by forming the interferometer to have a phase modulator in each leg. Applying the electrical signal to the phase modulators, which are connected in push-pull, changes the optical path length difference between the interferometer legs and produces an optical signal that can be transmitted to a remote location. A photodetector at the remote location converts the optical signal into an electrical signal that can be processed to measure changes in the parameter. The sensors may be used singly, or a plurality of sensors may be arranged in a geophone array.
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Patent Agency Ranking
公开(公告)号：NO20003686A
公开(公告)日：2001-01-31
申请号：NO20003686
申请日：2000-07-18
Applicant: LITTON SYSTEMS INC
Inventor： HALL DAVID B
CPC classification number: G01D5/35303 , G01J9/02
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公开(公告)号：NO20002415L
公开(公告)日：2000-11-13
申请号：NO20002415
申请日：2000-05-09
Applicant: LITTON SYSTEMS INC
Inventor： HALL DAVID B
Abstract: Quadrature signals Q and in-phase signals I output from a pathlength mismatched interferometric sensor array (10) are normalized by sampling the signals to obtain a first set of values Qk = Q0Bk sin φk corresponding to the sine of the phase shift and a second set of values Ik = I0Bk cos φk corresponding to the cosine of the phase shift where k is a running index of the set of consecutive samples of Q and I. A quantity DQk =|Qu(k))2 -(Qs(k))2| is calculated for the quadrature signals; and a quantity DIk = |(Iu(k))2 -(Is(k))2| is calculated for the in-phase signals, where u(k) and s(k) are parameters used to determine indices that select specific sampled signals and k is a running index of the set of consecutive samples of Q and I. The normalization factor is then calculated as the ratio R = QNIN whereQN = k=N1N2 DQk andIN = k=N1N2DIk.
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公开(公告)号：CA2306681A1
公开(公告)日：2000-11-10
申请号：CA2306681
申请日：2000-04-26
Applicant: LITTON SYSTEMS INC
Inventor： HALL DAVID B
Abstract: Quadrature signals Q and in-phase signals I output from a pathlength mismatched interferometric sensor array (10) are normalized by sampling the signals to obtain a first set of values Qk = Q o B k sin ~k corresponding to the sine of the phase shift and a second set of values I k = I o B k cos ~k corresponding to the cosine of the phase shift where k is a running index of the set of consecutive samples of Q and I. A quantity DQ k = ¦(Q u(k) -(Q s(k))2¦ is calculated for the quadrature signals; and a quantity DI k =¦(I u(k))2 -(I s(k))2¦ is calculated for the in-phase signals, where u(k) and s(k) are parameters used to determine indices that select specific sampled signals and k is a running index of the set of consecutive samples of Q and I. The normalization factor is then calculated as the ratio R = where Qn = and I n = .
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公开(公告)号：AU726485B2
公开(公告)日：2000-11-09
申请号：AU5936498
申请日：1998-03-18
Applicant: LITTON SYSTEMS INC
Inventor： HALL DAVID B
Abstract: A pressure sensing system (10) employs a plurality of pulsed lasers (12a, 12b, 12c, 12d), each emitting a distinct wavelength ( lambda 1, lambda 2, lambda 3, lambda 4) whereby a multiplexed incident beam is generated. The incident beam is split into a first portion directed to a first photodetector (18) that generates a reference signal (R) for each wavelength, and a second portion that interrogates a Fabry-Perot pressure sensor (16). The interrogation beam portion is phase-modulated by gap width variations in the sensor, and is transmitted to a second photodetector (20) that generates a measured intensity signal (5) for each wavelength. For each wavelength, the ratio (S/R) of the measured intensity signal (S) to the reference intensity signal (R) is taken, and yields two terms, one of which is an interference term that is proportional to the cosine of the Fabry-Perot phase shift angle phi , which is a function of the gap width. By choosing wavelengths that are in quadrature relationship for a nominal. Fabry-Perot gap width, the algebraic differences can be taken among the ratios to yield two expressions proportional, respectively, to the cosine and sine of the phase shift angle phi . An arctangent calculation is used to obtain the measure of phi , which is proportional to the gap width, which, in turn, is a known function of the pressure applied to the sensor (16).
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公开(公告)号：NO985501A
公开(公告)日：1999-05-27
申请号：NO985501
申请日：1998-11-25
Applicant: LITTON SYSTEMS INC
Inventor： HALL DAVID B , FREDERICK DONALD A , BUNN JAMES B , BUNN JR JAMES B
IPC: G01J9/00
CPC classification number: G01J9/00
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