公开(公告)号：JPH11118494A

公开(公告)日：1999-04-30

申请号：JP23789898

申请日：1998-07-22

Applicant: LITTON SYSTEMS INC

Inventor： STEELE JAMES R ,  CORDOVA AMADO ,  GOLDNER ERIC LEE

IPC: G01C19/72

Abstract: PROBLEM TO BE SOLVED: To stabilize the magnification of an optical fiber rotating sensor by arranging a depolarizer within an optical path between an optical coupler and an integrated optical chip, and depolarizing a light signal to prevent the change of polarized state in the propagation to an interferometer. SOLUTION: A multiple optical coupler (MUX) 34 imparts an output to an optical fiber 35. The optical fiber 35 guides the optical output from a Lyot depolarizer 36 to a multifunctional integrated optical chip 37. The integrated optical chip 37 comprises waveguides 38-40 forming a Y-coupler 42. The light inputted to a detecting coil 48 through a pigtail 33 forms a clockwise light wave within the detecting coil 48. The light inputted from the pigtail 46 to the detecting coil 48 forms a counterclockwise light wave. The clockwise and counterclockwise light waves form an interference pattern within the detecting coil 48. A magnification error is caused by the change of polarized state of light and the succeeding polarization by the filter action in the integrated optical chip 37. By inserting the depolarizer 25, the polarized state of light is stabilized, and the magnification error is eliminated.

公开(公告)号：JPH10318761A

公开(公告)日：1998-12-04

申请号：JP12434098

申请日：1998-05-07

Applicant: LITTON SYSTEMS INC

Inventor： AUERBACH DANIEL E ,  CORDOVA AMADO ,  GOLDNER ERIC L ,  HIGBEE JOHN E ,  STEELE JAMES R ,  WONG KA KHA

IPC: G01P9/00 ,  G01C19/72

Abstract: PROBLEM TO BE SOLVED: To avoid the influence of an intensity spike by dividing light energy output into a plurality of light beams and emitting them into a fiber, propagating them inversely within a coil, adding a periodical artificial phase difference, and recombining a single light output signal. SOLUTION: A light energy source 16 passes through an optical fiber 18, advances toward a coupler 20 and a polarizer 22, and emits a light energy with a predetermined wavelength and bandwidth. Then, a coupler 24 receives the output of the polarizer 22 and divides it into a pair of waves that are reversely propagated in the coil 26 of the optical fiber. A phase modulator 28 is located in an optical path between the coupler 24 and the optical fiber sensor coil 26 and gives a periodical, artificial phase difference between light waves that are reversely propagated in the coil 26. Modulated, reverse propagation waves are coupled so that they interfere each other by the coupler 24. Before the application to a photodetector 32, a light signal is operated, the intensity of the light signal is periodically attenuated, and an intensity spike is eliminated before converting to the information of electrical regions from light.

公开(公告)号：DE69826788D1

公开(公告)日：2004-11-11

申请号：DE69826788

申请日：1998-06-25

Applicant: LITTON SYSTEMS INC

Inventor： STEELE JAMES R ,  CORDOVA AMADO ,  GOLDNER ERIC LEE

IPC: G01C19/72 ,  H01S3/06

Abstract: A fiber optic rotation sensor system having improved scale factor stability includes an optically pumped gain fiber arranged to provide optical signals to an integrated optics chip connected to a fiber optic sensing coil. An optical coupler receives optical signals from the gain fiber and provides the optical signals to an optical fiber. The optical fiber is arranged to guide optical signals from the optical coupler along an optical path toward the integrated optics chip such that optical signals from the gain fiber are input to the fiber optic sensing coil to form counter-propagating waves therein. The counter-propagating waves traverse the sensing coil and then combine in the integrated optics chip to form a gyro output signal. A depolarizer is placed in the optical path between the first optical coupler and the integrated optics chip to prevent random changes in the state of polarization of optical signals propagating between the gain fiber and the integrated optic chip.

公开(公告)号：CA2240086A1

公开(公告)日：1999-01-23

申请号：CA2240086

申请日：1998-06-08

Applicant: LITTON SYSTEMS INC

Inventor： GOLDNER ERIC LEE ,  CORDOVA AMADO ,  STEELE JAMES R

IPC: G01C19/72

Abstract: A fiber optic rotation sensor system having improved scale factor stability includes an optically pumped gain fiber arranged to provide optical signals to an integrated optics chip connected to a fiber optic sensing coil. An optical coupler receives optical signals from the gain fiber and provides the optical signals to an optical fiber. The optical fiber is arranged to guide opti cal signals from the optical coupler along an optical path toward the integrated optics chip such that optical signals from the gain fiber are input to the fiber optic sensing coil to form counter-propagating waves therein. The counter-propag ating waves traverse the sensing coil and then combine in the integrated optics chip to form a gyro output signal. A depolarizer is placed in the optical path between the first optical coupler and the integrated optics chip to prevent random changes in the state of polarization of optical signals propagating between the gain fiber and the integrated optic chip.

公开(公告)号：CA1298635C

公开(公告)日：1992-04-07

申请号：CA561355

申请日：1988-03-14

Applicant: LITTON SYSTEMS INC

Inventor： STEELE JAMES R

IPC: G01C19/64 ,  G01C19/72

Abstract: ROTATION RATE NULLING SERVO AND METHOD FOR FIBER OPTIC ROTATION SENSOR Setting the driving signal of a phase modulator in the sensing loop of a fiber optic gyroscope to zero for a period of time ? equal to the transit time of the light waves through the gyro causes the gyro to assume a known zero reference state. In this zero reference state the counterpropagating light waves are in phase except for the phase shift caused by rotation of the sensing loop. During this zero reference state, a bias signal for demodulation purposes and a signal that will cause a phase shift equal and opposite to the rotation-induced phase shift are applied to the phase modulator. These signals null the rotationinduced phase shift as seen by a photodetector for a period equal to the transittime.

公开(公告)号：CA1198179A

公开(公告)日：1985-12-17

申请号：CA418336

申请日：1982-12-22

Applicant: LITTON SYSTEMS INC

Inventor： MARK JOHN G ,  STEELE JAMES R ,  HANSEN CRAIG C

IPC: H03L7/08 ,  H03L5/00 ,  H03L7/085 ,  H03L7/087

Abstract: RESIDUAL MODE PHASE LOCKED LOOP A phase locked loop is disclosed which subtracts an estimated signal from an input signal and operates upon the residual signal. The residual signal is demodulated and applied to a controlled oscillator which produces feedback signals approximately the sine and cosine of the input signal. The cosine feedback signal is multiplied by the residual signal whose resultant signal is a frequency correction signal. The sine feedback signal is multiplied by the residual signal for multiplication again by the sine feedback signal to produce the estimated signal which is amplitude and frequency controlled. This signal is then subtracted from the input signal to reduce the residual signal to near zero.

公开(公告)号：DE69826788T2

公开(公告)日：2006-02-09

申请号：DE69826788

申请日：1998-06-25

Applicant: LITTON SYSTEMS INC

Inventor： STEELE JAMES R ,  CORDOVA AMADO ,  GOLDNER ERIC LEE

IPC: G01C19/72 ,  H01S3/06

Abstract: A fiber optic rotation sensor system having improved scale factor stability includes an optically pumped gain fiber arranged to provide optical signals to an integrated optics chip connected to a fiber optic sensing coil. An optical coupler receives optical signals from the gain fiber and provides the optical signals to an optical fiber. The optical fiber is arranged to guide optical signals from the optical coupler along an optical path toward the integrated optics chip such that optical signals from the gain fiber are input to the fiber optic sensing coil to form counter-propagating waves therein. The counter-propagating waves traverse the sensing coil and then combine in the integrated optics chip to form a gyro output signal. A depolarizer is placed in the optical path between the first optical coupler and the integrated optics chip to prevent random changes in the state of polarization of optical signals propagating between the gain fiber and the integrated optic chip.

公开(公告)号：CA2240086C

公开(公告)日：2001-09-11

申请号：CA2240086

申请日：1998-06-08

Applicant: LITTON SYSTEMS INC

Inventor： CORDOVA AMADO ,  STEELE JAMES R ,  GOLDNER ERIC LEE

IPC: G01C19/72

Abstract: A fiber optic rotation sensor system having improved scale factor stability includes an optically pumped gain fiber arranged to provide optica l signals to an integrated optics chip connected to a fiber optic sensing coil . An optical coupler receives optical signals from the gain fiber and provides th e optical signals to an optical fiber. The optical fiber is arranged to guide optical signals from the optical coupler along an optical path toward the integrated optics chip such that optical signals from the gain fiber are input to the f iber optic sensing coil to form counter-propagating waves therein. The counter-pr opagating waves traverse the sensing coil and then combine in the integrated optics chip to form a gyro output signal. A depolarizer is placed in the optical path between the first optical coupler and the integrated optics chip to prevent random changes in the state of polarization of optical signa ls propagating between the gain fiber and the integrated optic chip.

公开(公告)号：CA2235896A1

公开(公告)日：1998-11-12

申请号：CA2235896

申请日：1998-04-27

Applicant: LITTON SYSTEMS INC

Inventor： CORDOVA AMADO ,  STEELE JAMES R ,  GOLDNER ERIC L ,  HIGBEE JOHN E ,  AUERBACH DANIEL E ,  WONG KA KHA

IPC: G01P9/00 ,  G01C19/72

Abstract: An interferometric rotation rate sensor is arranged to overcome effects of the unavoidable generation of intensity spikes in the modulated optical output. An electrooptical device is located within the optical path of the sensor for receiving the optical output signal from the sensor coil and transforming it prior to application to the photodetector. The electrooptical device is driven by a periodic electrical signal with a period equal to the loop transit time of light traveling through the sensor coil. By synchronizing the periods of attenuation with the predictable presence of spikes in the optical output, valid optical signal information is preserved while gyro electronics are sheltered from the results of optical intensity spiking.