公开(公告)号：JPH10206172A

公开(公告)日：1998-08-07

申请号：JP35478697

申请日：1997-12-24

Applicant: LITTON SYSTEMS INC

Inventor： CORDOVA AMADO ,  FERSHT SAMUEL N

IPC: G01C19/72

Abstract: PROBLEM TO BE SOLVED: To minimize a bias error introduced from an environment by receiving an output from an optical energy source as a pair of beams propagated in a relative direction by an embedded coil, and supplying obtained interference pattern as a gyro output to a detector. SOLUTION: Shupe (phonetic) bias error is minimized by replacing part of a sensor coil 18 with a dummy layer. The layer forms part of a wound coil structure, but does not carry or transmit an optical signal responding to rotation. Such a layer contributes to a second element 24 of the coil 18. If the layer has thermomechanical characteristics similar to characteristics of the embedded sensor coil, plotting contributing to Shupe integration is not corrected due to the presence of the layer. A rotation responding element includes a small fiber layer that contribution to the integration at all temperatures. Accordingly, small Shupe bias error is produced by the integration of the responding element.

公开(公告)号：JPH10185585A

公开(公告)日：1998-07-14

申请号：JP31826297

申请日：1997-11-19

Applicant: LITTON SYSTEMS INC

Inventor： CORDOVA AMADO ,  HOOVER ROBERT J ,  MCLEAN THOMAS ,  PATTERSON RALPH A ,  RAHN JOHN P

IPC: G01C19/72 ,  G02B6/44

Abstract: PROBLEM TO BE SOLVED: To reduce gyro errors by releasing the stress between windings, by providing a means which reduces the thermal stress between a jacket and a burying material. SOLUTION: A surface 26 of the external jacket of the sensor coil composed of an optical fiber 28 is insulated from a surrounding burying material 30 by lubricant layers 32 and 34, which surround the wound layer of a fiber 29. Before starting the winding process of the sensor coil, the lubricant layer applying process, and the burying process of the sensor coil, the burying material 30 is applied to the surface of a supporting mandrel. After the material 30 is applied, the lubricant layer 34 is applied to the surface of the burying material 30 with a brush or spray and the layer of the fiber 28 is wound. After the fiber 28 is wound, the lubricant layer 32 is applied to the surface of the fiber 28 with a spray or brush, and the remaining layer of the burying material 36 is applied. Since the lubricant layers 34 and 32 are respectively provided immediately below and above the fiber 28, the fiber 28 is isolated from the layers 30 and 36 of the burying material 30 by the lubricants.

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：JPH1164006A

公开(公告)日：1999-03-05

申请号：JP15185998

申请日：1998-04-23

Applicant: LITTON SYSTEMS INC

Inventor： CORDOVA AMADO

IPC: G01C19/72

Abstract: PROBLEM TO BE SOLVED: To control nonreciprocity (Shupe effect) due to vibration and heat to a minimum, and make it adjustable by controlling and adjusting geometrical factors of a coil subjected to potting treatment. SOLUTION: Geometrical factors of an optical fiber coil subjected to potting treatment (potting treatment length, number of turns per layer, number of layers and thickness of an adhesion layer) are set so as to fit to the restriction of a system/gyroscope such as the maximum allowable volume and the desired Sagnac magnification. As a variable from geometrical factors, parameter, e.g. the thickness of an adhesion layer is selected, a plurality of coils are wound, and the selected geometrical factors are changed. Each Shupe bias (vibration response or thermal gradient response) is measured. The optimum value and the allowable degree (tolerance) of the geometrical factor are selected. In the course of coil manufacturing, the geometrical factors are controlled to be in a specified tolerance.

公开(公告)号：JPH10300479A

公开(公告)日：1998-11-13

申请号：JP11166897

申请日：1997-04-30

Applicant: LITTON SYSTEMS INC

Inventor： MARK JOHN G ,  DANIEL A TAZARUTES ,  CORDOVA AMADO

IPC: G01C19/72

Abstract: PROBLEM TO BE SOLVED: To solve the problem of bias by electronic cross coupling by applying the sequence of an artificial phase shift within a specified range of an interferometer to optical beams propagated in the opposite directions, and driving a modulator for making the duration of each phase shift equal to the passing time of a sensor coil. SOLUTION: In the area of overmodulation between optical beams propagated in the opposite directions within the sensor coil of a Sagnac interferometer, a sequence of artificial phase shift is applied. The sequence is formed of phase shifts of ±aπ/2b and ±(4b-a)π/2b (wherein (a) is an odd integer, and (b) is an integer larger than 1). The waveform for driving a phase modulator is introduced from 2π radian so that the values of adjacent drive signals are differed by a π/2b or -(4b-a)π/2b in a first angle direction, and differed by -aπ/2b or (4b-a)π/2b in an angle direction opposite thereto.

公开(公告)号：JPH11101646A

公开(公告)日：1999-04-13

申请号：JP21637098

申请日：1998-07-31

Applicant: LITTON SYSTEMS INC

Inventor： RAHN JOHN P ,  CORDOVA AMADO

IPC: G01C19/72 ,  G02B6/00

Abstract: PROBLEM TO BE SOLVED: To reduce the effect of the temperature change-induced optical path length unbalance based on bias stability by making an optical fiber include an inside cover material made of silicone and a specific filler. SOLUTION: The sensor coil 10 is an important constituting element of an optical fiber gyroscope, and it is fixed to a platform of which revolving speed is to be measured. The sensor coil 10 is wound on a support spool 14, and it is made of an optical fiber 12 operated as a light guide receiving a reverse propagation beam pair emitted from a common light source. The optical fiber 12 contains an inside cover material made of silicone and a proper filler. Carbon black, alumina, a hafnium oxide or silica is used for as proper filler. The bias error caused by temperature change-induced optical path asymmetry is the integration function of optical path length strain, and it can be reduced by introducing a proper filler in the inside cover material of the optical fiber 12.

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：WO9804884A3

公开(公告)日：1998-03-12

申请号：PCT/US9711136

申请日：1997-06-26

Applicant: LITTON SYSTEMS INC ,  MARK JOHN G ,  TAZARTES DANIEL A ,  CORDOVA AMADO ,  CHERBETTCHIAN AGOP H ,  GOLDNER ERIC L

Inventor： MARK JOHN G ,  TAZARTES DANIEL A ,  CORDOVA AMADO ,  CHERBETTCHIAN AGOP H ,  GOLDNER ERIC L

IPC: G01C19/72

CPC classification number: G01C19/722

Abstract: A gyroscope assembly (10) includes a ring-shaped fiber optic coil (14) and a coil conforming enclosure (12, 16) of high magnetic permeability ferromagnetic material. The enclosure is ring-shaped to conform with the shape of the coil, and includes a portion (22) extending within the internal hole of the coil ring. Therefore, the coil is intimately and fully encased within high magnetic permeability material. In particular, the enclosure comprises a coil supporting spool (12) and a cover (16) secured to the spool. The spool includes a base (18) which is provided with a central hole (20) and a tubular wall (22) extending perpendicularly from the base. Coil (14) is bonded to base (18). Both the spool and the cover are formed of high magnetic permeability material, and the cover is placed about the fiber optic coil and attached to the spool. The coefficient of thermal expansion material used for the spool is matched to that of the coil pack to minimize stress imposed upon the fiber. An outer shield (28), roughly cylindrical in shape, may be further attached to the outside of the inner, toroidal shield, and the two shields are separated by a layer of low magnetic permeability material, such as of low magnetic permeability stainless steel or aluminum. 00000

Abstract translation: 陀螺仪组件（10）包括环形光纤线圈（14）和高磁导率铁磁材料的线圈合格外壳（12,16）。 外壳是环形的以符合线圈的形状，并且包括在线圈环的内部孔内延伸的部分（22）。 因此，线圈密封并完全封装在高磁导率材料内。 特别地，外壳包括线圈支撑线轴（12）和固定到线轴的盖（16）。 阀芯包括设置有中心孔（20）的底座（18）和从基座垂直延伸的管状壁（22）。 线圈（14）结合到基座（18）上。 卷轴和盖都由高磁导率材料形成，并且盖围绕光纤线圈放置并连接到卷轴。 用于卷轴的热膨胀材料系数与线圈组的热膨胀系数相匹配，以使施加在纤维上的应力最小化。 大致圆筒形的外屏蔽件（28）可以进一步附接到内环形屏蔽体的外部，并且两个屏蔽件被低磁导率材料层（例如低磁导率不锈钢）分开，或 铝。 00000

公开(公告)号：CA2236313A1

公开(公告)日：1999-02-01

申请号：CA2236313

申请日：1998-04-30

Applicant: LITTON SYSTEMS INC

Inventor： CORDOVA AMADO ,  RAHN JOHN P

IPC: G01C19/72 ,  G02B6/00

Abstract: A sensor coil for a fiber optic gyroscope includes fiber with an inner jacket of predetermined composition for reducing the effects of temperature-change-induced optical length asymmetry upon bias stability. Filler material of predetermined composition is combined with silicone and deposited upon the glass fiber, forming an inner jacket. The composition of the inner jacket is adjusted to thereby effect the Poisson ratio of the inner jacket and thereby reduce the isotropic thermally-induced pressure within the wound coil resulting in reduced temperature-induced optical length asymmetry and improved bias stability.

公开(公告)号：CA2202433A1

公开(公告)日：1998-10-11

申请号：CA2202433

申请日：1997-04-11

Applicant: LITTON SYSTEMS INC

Inventor： TAZARTES DANIEL A ,  MARK JOHN G ,  CORDOVA AMADO

IPC: G01C19/72

Abstract: A phase modulator applies sequences of artificial phase shifts in the region of overmodulation between light beams counterpropagating within the sensor coil of a Sagnac interferometer to obtain improved random walk performance. The sequences are composed of phase shifts of ~a.pi./2b and ~(4b-a).pi./2b where a is an odd integer and b is an integer greater than 1. The waveform for driving the phase modulator is derived from a 2.pi. radian mapping plotted so that adjacent driving signal values differ by a.pi./2b or -(4b-a).pi./2b in a first angular direction and by -a.pi./2b or by (4b-a).pi./2b in the opposite angular direction. Angular transitions about the mapping may be predetermined to generate a deterministic, random, or pseudo-random modulation sequence. In the event that a deterministic sequence is chosen, it is examined for orthogonality properties to assume zero average output bias from crosstalk.