Litton Systems, Inc.

Copley Networks, Inc.

Leland Stanford Junior University

Amado Cordova

John P Rahn

Eric Lee Goldner

Daniel A Tazartes

John G Mark

Samuel N Fersht

Thomas McLean

Agop Hygasov Cherbettchian

Ronald James Michal

Ralph A Patterson

James R Steele

Kurt R Carlson

Glenn M Surabian

Donald J Bilinski

Herbert J Shaw

Robert L Byer

Martin M Fejer

George A Pavlath

Shoichi Sudo

Robert J Hoover

Chin L Chang

Arthur D Lang

Michael Digonnet

Celestino Gaeta

John D Wilde

Daniel Eugene Auerbach

John E Higbee

Ka Kha Wong

Thomas Meloeny

Kenneth Bean

Trong-Huang Lee

Paul A Hinman

Jyl Ren Dent

Gene H Chin

An optical fiber interleaver and method for aligning the output channels to a set of nominal values in frequency space. The interleaver is formed of two optical fibers joined together at fused input and output couplers to define an input section, an interferometer section and an output section. Within the interferometer section, an element is arranged to vary the optical path length of at least one of the fibers in response to a feedback signal. The feedback signal is generated by examination of the intensity of a monitor signal at the output section that was applied at the input section.

Tuned fiber optic interleaver

An optical interleaver. The interleaver is based upon the Mach Zender interferometer. At least one of the optical paths joining opposed couplers of the arrangement includes an optical image transfer element intermediate the ends of fibers associated with the couplers. In one embodiment, the optical image transfer element is a single imaging lens whereas, in another embodiment, the element consists of an aligned pair of collimating lenses. During fabrication, optical positioning stages support the optical image transfer element and fiber ends to permit ready adjustment of &Dgr;&THgr;, the optical path length difference between the arms of the interleaver, to assure predetermined optical channel spacing of an input DWDM signal.

Optical interleaver with image transfer element

A potting compound for use in the fabrication of fiber optic gyro sensor coils utilizes a silver-filled silicone base to reduce gyro sensitivity to changes in heat rate and thereby improve gyro performance during warm-up and periods of thermal cycling.

Potting compound for fabrication of fiber optic gyro sensor coil and method for fabricating sensor coil

A tool for forming a sensor coil that may be employed, for example, in a fiber optic gyroscope with reduced Shupe effect-induced bias. The tool includes a takeup reel having a cylindrical mandrel with inner flanges fixed to its opposed ends sandwiched between two outer flanges. Each of the inner flanges includes a pair of radially-directed apertures that form a radially-directed wedge therebetween. A recess in the planar portion of each of the outer flanges that contacts an inner flange is aligned with the apertures. This permits the winding of the sensor coil to form climbing turns at the ends of wound layers that lie outside an encapsulated fiber pack. Such turns, which join layers with overlying layers, avoid crossovers and the resultant stress that contributes significantly to Shupe effect-induced bias. A sensor coil having reduced internal stress is thus also provided.

Fiber optic sensor coil and tool for forming same

Potting compound for fabrication of fiber optic gyro sensor coil and

A method and apparatus for reducing the temperature-dependent Shupe bias of a potted gyro sensor coil pack to near-zero is provided by selectively adjusting the manner in which CCW and CW fiber leads are attached to the coil pack or the coil mount. The invention recognizes the inevitable existence of a strain differential between the CW and CCW-wound portions of a symmetrically-wound fiber coil. Leads affixed to the ends of the CW and CCW-wound halves of the coil are selectively bonded in accordance with principles for creating a counteracting temperature-dependent stress differential whereby temperature-dependent Shupe bias is substantially eliminated from the gyro output.

Method for stress tuning fiber optic sensor coils

An improved dressing for the fiber optic leads of a fiber optic gyroscope sensing coil and method for forming the same. A pair of fiber optic leads connect the sensing coil of a rotation sensing device to an integrated optics chip. The fiber optic leads are originally arranged to extend around the fiber optic sensing coil in different directions. The leads are formed of unequal lengths, where the longer of the leads is extended along an outer circumference of the sensing coil. The longer lead is bent so that the circumferential direction of longer lead reverses itself, and the longer lead then extends around the sensing coil in the same direction as the shorter lead. A low modulus adhesive is applied to the leads and cured to initially bond the leads in place against the sensing coil. The pair of leads are then wound in the same circumferential direction adjacent to each other fashion around the outer circumference of the sensing coil. After the desired amount of winding has been completed, a predetermined length of each of the leads is left available to be routed to the rotation sensing device. The entire outer surface of the wound fiber optic leads surrounding the temporary adhesion is then coated with a low modulus adhesive and cured to bond the wound leads against the sensing coil structure.

Fiber optic gyroscope coil lead dressing and method for forming the same

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.

Apparatus and method for scale factor stabilization in interferometric

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.

High efficiency magnetic shield for a fiber optic gyroscope

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.

Gyro sensor coil with filled optical fiber

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.

Fiber optic gyro with optical intensity spike suppression

A method for providing an optical fiber coil having reduced bias vibration and bias temperature-ramp sensitivity by controlling and adjusting coil geometrical factors including the coil potted length, the adhesive layer thickness, the number of turns per layer, the number of layers and the way the winding is terminated. The windings may be terminated to form the coil as a complete quadrupole, a diapole, an incomplete quadrupole or an incomplete diapole. By adjusting geometrical factors of the coil design, a coil for which the residual net Shupe bias is negligible is obtained.

Reduction of fiber optic gyroscope vibration and temperature-ramp

A gyroscope component (10) and its variations (10a, 10b and 10c) includes a spool (12, 12a) which supports a ring-shaped fiber optic gyroscope coil (14). The spool has a base (26, 26a) which is provided with a central hole (38, 38a). A perpendicularly extending tubular wall (28, 28a) extends from the base or a cover (16, 16a), and may directly contact the coil or be separated therefrom by a non-adhesive material (29) or a space (30). The cover covers the spools and, with the spool and the tubular wall, forms a ring-shaped enclosure. Each coil has a generally trapezoidal shape and comprises an optical fiber winding wound about an axis and having a cross-sectional configuration that approximates a 45.degree. right triangle whose hypotenuse is formed by the sloped sides to provide a side which is sloped with respect to its axis. Three components (10, 10', 10'') are positioned respectively about three orthogonally disposed axes to form an assembly (50) and are supported within and enclosed by a housing (52). The arrangement of the enclosures positions the coils such that their sloped hypotenuse sides face one another. The spool (12, 12a), the cover (16, 16a), the tubular wall (28, 28a) and the housing (52) are formed of a ferromagnetic material having high relative (.mu./.mu.0) permeability.

Conically arranged fiber optic gyroscope coils

A sensor coil for a fiber optic gyroscope. A continuous optical fiber is coated with bonding material of predetermined composition such as a thermoplastic material that exhibits a bond strength of at least 100 p.s.i. in tension, equivalent to at least 40 p.s.i. in shear. The coated fiber is arranged into a predetermined winding pattern whereby contacting portions of adjacent coil turns are bonded to one another. Void spaces between contacting portions of bonded turns reduce the volume of bonding material employed (as opposed to a filled potted sensor coil). The coil does not experience the differential in expansion along the axial and radial directions to the degree that has, for example, required the use of single flanged spools in the prior art. Its use with dual-flanged spools permits mounting arrangements that promote coil stiffness, thereby enhancing gyro performance in the presence of vibration.

Bonded fiber optic gyro sensor coil including voids

A sensor coil for a fiber optic gyroscope. At least one dummy layer forms an integral structure with, and shares the thermal expansion characteristics of, a potted coil comprising a plurality of layers of windings of a first optical fiber. In a gyroscope, the potted coil is arranged to receive the output of a source of optical energy as a pair of beams that counter-propagate therein and to provide the resultant interference pattern, as gyro output, to a detector. The dummy layer displaces layers or windings of the potted coil from regions likely to contribute to Shupe bias effects.

Growing community of inventors

West Hills, CA, United States of America

Amado Cordova