-
41.发明专利
公开(公告)号：AU2855300A
公开(公告)日：2000-12-05
申请号：AU2855300
申请日：2000-01-21
Applicant: LITTON SYSTEMS INC
Inventor： HODGSON CRAIG W , FREDERICK DONALD A
IPC: G01D5/26 , G01D5/353 , G08B13/186 , H04B10/17
-
公开(公告)号：AU720644B2
公开(公告)日：2000-06-08
申请号：AU7180798
申请日：1997-11-14
Applicant: LITTON SYSTEMS INC
Inventor： FERSHT SAMUEL N , FREDERICK DONALD A
-
公开(公告)号：NO990340L
公开(公告)日：1999-03-25
申请号：NO990340
申请日：1999-01-25
Applicant: LITTON SYSTEMS INC
Inventor： FREDERICK DONALD A
Abstract: A fiber optic sensor comprises a first optical signal source that produces an optical signal of wavelength lambda 1 and a second optical signal source that produces an optical signal of wavelength lambda 2. A first WDM coupler is connected to the first and second optical signal sources to combine signals output therefrom. An optical fiber is connected to the WDM coupler to guide the combined optical signals therefrom. A second WDM coupler is connected to the optical fiber to separate the optical signals of wavelength lambda 1 and lambda 2. A fiber optic sensor array containing a plurality of fiber optic sensors is connected to the second WDM coupler and arranged such that optical signals of the wavelengths lambda 1 and lambda 2 are directed to different fiber optic sensors in the fiber optic sensor array. A third WDM coupler is arranged for combining signals of wavelength lambda 1 and lambda 2 output from the fiber optic sensor array. FDM multiplexing apparatus is connected to the third WDM coupler apparatus, Demultiplexing and demodulating apparatus is connected to the FDM multiplexing apparatus for producing output signals corresponding to the fiber optic sensors.
-
公开(公告)号：NO983281L
公开(公告)日：1999-02-01
申请号：NO983281
申请日：1998-07-16
Applicant: LITTON SYSTEMS INC
Inventor： FREDERICK DONALD A , BELL STEVEN G
Abstract: A system (10) for performing high resolution measurement of frequency variations in multimode fiber laser acoustic sensors having an end-pumped active fiber sensor (16) emitting a plurality of lasing modes, wherein precise frequencies of the lasing modes emitted are dependent upon a strain acting on said acoustic sensor. An optical fiber (14) is connected to the active fiber sensor (16) for transmitting the lasing modes. The optical fiber transmits the multiple lasing modes to an optical amplifier fiber (22) where the lasing mode signals are amplified. The amplified lasing modes signals are then fed through a phase modulator (34) connected to the optical fiber for applying a phase generated carrier on the lasing mode signals. The output from the phase modulator (34) is supplied to a receiving interferometer (36) having a predetermined path imbalance for interferometrically analyzing the frequency shifts of each of the lasing mode signals, wherein the predetermined path imbalance is matched with the longitudinal mode spacing between the lasing modes of the active fiber sensor. A demodulation unit (46) is connected to the receiving interferometer (36) for receiving and demodulating the output of the receiving interferometer to determine the frequency shift incurred by the lasing mode signals, wherein the demodulated frequency shift is proportional to the strain acting on the acoustic sensor. In an alternative embodiment, a plurality of active fiber sensors may be pumped by a single laser light source with their outputs multiplexed together and fed through the receiving interferometer for interferometric analysis of all the signals.
-
公开(公告)号：CA2240550A1
公开(公告)日：1999-01-31
申请号：CA2240550
申请日：1998-07-07
Applicant: LITTON SYSTEMS INC
Inventor： FREDERICK DONALD A , HALL DAVID B
Abstract: A pressure measuring device which utilizes an array of optical, non-acoustic pressure sensors with a laser light source which generates a pulsed light signal into a light transmitting cable, wherein the pulsed light signal propagates along the light transmitting cable through the array of optical pressure sensors. A plurality of optical couplers are attached to the light transmitting cable at multiple locations spaced apart from one another in order to branch off at least a portion of the pulsed light each location. Each of the plurality of optical couplers includes a respective optical pressure sensor and a pressure insensitive reflector, wherein the branched off portion of the pulsed light signal is transmitted into to both the optical pressure sensor and the reflector. Each optical pressure sensor reflects a pressure indicating signal ba ck into the optical coupler, while the pressure insensitive reflector reflects a reference signal back into the optical coupler. The pressure indicating signal and the reference signal are reflected through the optical coupler into the ligh t transmitting cable as a pair of non-overlapping pulsed signals, which are then retrieved from the light transmitting cable by a signal detector. The retrieved pressure indicating signal is compared with the retrieved reference signal to determine the pressure acting upon the optical pressure sensor.
-
Patent Agency Ranking
公开(公告)号：NO990340D0
公开(公告)日：1999-01-25
申请号：NO990340
申请日：1999-01-25
Applicant: LITTON SYSTEMS INC
Inventor： FREDERICK DONALD A
Abstract: A fiber optic sensor comprises a first optical signal source that produces an optical signal of wavelength lambda 1 and a second optical signal source that produces an optical signal of wavelength lambda 2. A first WDM coupler is connected to the first and second optical signal sources to combine signals output therefrom. An optical fiber is connected to the WDM coupler to guide the combined optical signals therefrom. A second WDM coupler is connected to the optical fiber to separate the optical signals of wavelength lambda 1 and lambda 2. A fiber optic sensor array containing a plurality of fiber optic sensors is connected to the second WDM coupler and arranged such that optical signals of the wavelengths lambda 1 and lambda 2 are directed to different fiber optic sensors in the fiber optic sensor array. A third WDM coupler is arranged for combining signals of wavelength lambda 1 and lambda 2 output from the fiber optic sensor array. FDM multiplexing apparatus is connected to the third WDM coupler apparatus, Demultiplexing and demodulating apparatus is connected to the FDM multiplexing apparatus for producing output signals corresponding to the fiber optic sensors.
-
公开(公告)号：NO983282D0
公开(公告)日：1998-07-16
申请号：NO983282
申请日：1998-07-16
Applicant: LITTON SYSTEMS INC
Inventor： FREDERICK DONALD A , HALL DAVID B
Abstract: A pressure measuring device which utilizes an array of optical, non-acoustic pressure sensors (22) with a laser light source (12) which generates a pulsed light signal into a light transmitting cable (16), wherein the pulsed light signal propagates along the light transmitting cable through the array of optical pressure sensors. A plurality of optical couplers (18) are attached to the light transmitting cable (16) at multiple locations spaced apart from one another in order to branch off at least a portion of the pulsed light each location. Each of the plurality of optical couplers includes a respective optical pressure sensor (22) and a pressure insensitive reflector (26), wherein the branched off portion of the pulsed light signal is transmitted into both the optical pressure sensor (22) and the reflector (26). Each optical pressure sensor (22) reflects a pressure indicating signal back into the optical coupler (18), while the pressure insensitive reflector (26) reflects a reference signal back into the optical coupler. The pressure indicating signal and the reference signal are reflected through the optical coupler (18) into the light transmitting cable as a pair of non-overlapping pulsed signals, which are then retrieved from the light transmitting cable by a signal detector (32) . The retrieved pressure indicating signal is compared with the retrieved reference signal to determine the pressure acting upon the optical pressure sensor.
-
公开(公告)号：CA2278356C
公开(公告)日：2005-03-22
申请号：CA2278356
申请日：1999-07-22
Applicant: LITTON SYSTEMS INC
Inventor： FERSHT SAMUEL N , HALL DAVID B , FREDERICK DONALD A
Abstract: An optical waveguide (28) formed in an integrated optics substrate (30) is included in an optical path of an interferometer (51). An optical signal source (12) is arranged to provide an optical signal to the interferometer (51). A channel waveguide phase modulator (38) its formed on the substrate (30) and arranged to phase modulate optical signals guided by the optical waveguide (28). Signals from a geophon e (50) arranged to produce an electrical signal in response to mechanical vibration s are input to the phase modulator (38). The geophone (50) is connected to the channel waveguide phase modulator ((38) such that the electrical signal modulates the phase of the optical signal guided by the optical waveguide (28) so that the interference pattern output from the interferometer (51) indicates the amplitude of the mechanical vibrations . One or more optical fibers (24) are included in the interferometer (51) and are arranged to provide a mismatch between the interferometer path lengths
-
公开(公告)号：DE69721869T2
公开(公告)日：2004-02-19
申请号：DE69721869
申请日：1997-02-25
Applicant: LITTON SYSTEMS INC
Inventor： FREDERICK DONALD A , CAPPI JOHN F
Abstract: A hydrophone has a fibre optic interferometer with a reference arm (26) formed by a length of optical fibre wound around a rigid mandrel (30) and with constant optical path length, elastic material (42) over the arm, and a concentric sensing arm (24) with a length of optical fibre wound over the material in a coil so that optical path length changes when the hydrophone is exposed to an acoustic field. Optical output signals are passed to a processor to measure acoustic pressure. Preferably, the elastic material is preferably polyurethane, and the sensing arm is encased in further elastic material (44) and spaced from the reference arm. The mandrel is e.g. a solid rod of metal or other rigid material with end flanges, and the reference arm is potted.
-
公开(公告)号：NO20005444L
公开(公告)日：2001-04-30
申请号：NO20005444
申请日：2000-10-27
Applicant: LITTON SYSTEMS INC
Inventor： ROSCIGNO JOHN A , HODGSON CRAIG W , FREDERICK DONALD A , KNAACK WILLIAM C
-
-
-
-
-
-
-
-
-
Search Results
75
records
(took 0.024 seconds)
