公开(公告)号：CA2199087A1

公开(公告)日：1997-09-06

申请号：CA2199087

申请日：1997-03-04

Applicant: LITTON SYSTEMS INC

Inventor： CAPPI JOHN F ,  FREDERICK DONALD A

IPC: G01B9/02 ,  G01H9/00 ,  G01V1/18 ,  G02B6/36 ,  H04B13/00 ,  H04R1/44 ,  H04R23/00 ,  H04B10/12

Abstract: A fiber optic interferometric sensor for use in a hydrophone system at high pressures includes a reference fiber wrapped around a rigid inner cylinder. A solid layer of compliant material is applied over the reference fiber. The sensing arm of the interferometer is wound over the layer of material applied over the referenc e fiber. The outer material is sufficiently compliant to provide acoustic sensitivity com parable to that of air-backed hydrophones.

公开(公告)号：DE69914981D1

公开(公告)日：2004-04-01

申请号：DE69914981

申请日：1999-07-28

Applicant: LITTON SYSTEMS INC

Inventor： HALL DAVID B ,  FREDERICK DONALD A ,  FERSHT SAMUEL N

IPC: G01B9/02 ,  G01H9/00 ,  G01V1/16 ,  G01V1/22

公开(公告)号：CA2240550C

公开(公告)日：2003-12-02

申请号：CA2240550

申请日：1998-07-07

Applicant: LITTON SYSTEMS INC

Inventor： FREDERICK DONALD A ,  HALL DAVID B

IPC: H04B10/00 ,  G01L11/02 ,  G08C15/00

Abstract: A pressure measuring device which utilizes an array of optical, non-acoustic pressure sensors with a laser light source which generates a pulsedlight signal into a light transmitting cable, wherei n 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 back 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 light 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.

公开(公告)号：AT249117T

公开(公告)日：2003-09-15

申请号：AT00906981

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：NO20005442L

公开(公告)日：2001-04-30

申请号：NO20005442

申请日：2000-10-27

Applicant: LITTON SYSTEMS INC

Inventor： FREDERICK DONALD A ,  CARTER MICHAEL J ,  FERSHT SAMUEL N ,  WINSLOW DAVID C

IPC: G01H9/00 ,  G01V1/18 ,  G01V1/40 ,  G01V1/52 ,  G01V8/00

Abstract: A system for sensing subterranean acoustic waves emitted from an acoustic source includes a plurality of laser sources (LS1-LS6), a plurality of subterranean optical sensors (1000), at least one optical detector (D1-D16), and electronics (601). The laser sources each emit light at a different frequency. The subterranean optical sensors are hydrophones (1000) that receive the light and alter the light in response to the acoustic waves. The optical detector (D1-D16) receives the altered light and outputs an electrical signal. The electronics (601) receives the electrical signal and converts it into seismic data format. The hydrophones (1000) are able to operate at pressures of at least 5,000 psi and temperatures of at least 130 degrees Celsius. The hydrophone (1000) may be housed in a cable (1002) having a diameter of less than about 1.5 inches. The hydrophone's sensor preferably includes a reference mandrel (1110), two sensing mandrels (1120), and a telemetry can (1104), all of which are aligned in a coaxial, end-to-end configuration to reduce the profile of the hydrophone (1000). Flexible interlinks (1296) having grooves therein for receiving optical fiber join the mandrels (1110, 1120) together. The reference mandrel (1110) and sensing mandrels (1120) advantageously have hemispherically-shaped endcaps (1264), permitting them to operate at high pressure.

公开(公告)号：CA2369926A1

公开(公告)日：2000-11-23

申请号：CA2369926

申请日：2000-01-21

Applicant: LITTON SYSTEMS INC

Inventor： FREDERICK DONALD A ,  HODGSON CRAIG W

IPC: G01D5/26 ,  G01D5/353 ,  G08B13/186 ,  H04B10/17

Abstract: An optical sensor architecture receives an input optical signal (502) from a signal source (500) and outputs a perturbed optical signal (510) from at lea st one sensor (508) to a receiver (520). An optical amplifier (516) is position ed along a return fiber (512) at an optical distance at least 10 kilometers fro m the receiver (520), with the optical amplifier (516) amplifying the perturbe d optical signal (510) propagating to the receiver (520). If only one optical amplifier (516) is used, the optical distance between the amplifier (516) an d the receiver (520) may be between about 10 km and about 80 km, and an optica l distance of between about 10 km and about 150 km may separate the sensor (50 8) and the receiver (520). If additional optical amplifiers (544) and dedicated pump distribution fibers (540, 552) are used, the optical distances may be correspondingly greater. Alternatively, increasing the number of sensors (50 8) necessitates a reduction in the optical distance separating the sensors from shore.

公开(公告)号：CA2278356A1

公开(公告)日：2000-01-31

申请号：CA2278356

申请日：1999-07-22

Applicant: LITTON SYSTEMS INC

Inventor： FREDERICK DONALD A ,  FERSHT SAMUEL N ,  HALL DAVID B

IPC: G01B9/02 ,  G01H9/00 ,  G01V1/16 ,  G01V1/22

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 geophone (50) arranged to produce an electrical signal in response to mechanical vibrations 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：BR9802830A

公开(公告)日：1999-10-13

申请号：BR9802830

申请日：1998-07-31

Applicant: LITTON SYSTEMS INC

Inventor： FREDERICK DONALD A ,  HALL DAVID B

IPC: H04B10/00 ,  G01L11/02 ,  G08C15/00

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：CA2254251A1

公开(公告)日：1999-05-26

申请号：CA2254251

申请日：1998-11-18

Applicant: LITTON SYSTEMS INC

Inventor： BUNN JAMES S JR ,  HALL DAVID B ,  FREDERICK DONALD A ,  BUNN JAMES B

IPC: G01J9/00 ,  G01B9/02

Abstract: The invention is a method for obtaining a measure of the light propagation time difference for two light-propagating-media paths. The first step consists of gen erating two substantially-identical frequency-modulated light waves whereby the frequency of the light waves is offset from a reference frequency by a different frequency increment fo r each basic time interval in each of a plurality of groups of three or more basic time intervals. Each frequency increment is the sum of a specified increment and a frequency-modulation-error i ncrement. The frequency-modulation-error increments associated with the specified increments a re independent of each other and unknown. The second step consists of feeding the two light wav es into the entry points of two light-propagating-media paths having a light propagation tim e difference and obtaining a combination light wave by summing the light waves emerging from the exit points of the two light-propagating-media paths. The third step consists of calculating an estimated corrected or estimated uncorrected phase measure of the light propagation time d ifference for the two paths for a plurality of groups using only measured properties of the combin ation light wave. 16

公开(公告)号：BR9707145A

公开(公告)日：1999-05-18

申请号：BR9707145

申请日：1997-11-14

Applicant: LITTON SYSTEMS INC

Inventor： FERSHT SAMUEL N ,  FREDERICK DONALD A

IPC: G01L1/24 ,  G01B9/02 ,  G01D5/353 ,  G01J9/02 ,  G01K11/12