Litton Systems, Inc.

Northrop Grumman Systems Corporation

Other

Northrop Grumman Guidance and Electronics Company, Inc.

Northrop Grumman Corporation

John P Rahn

Amado Cordova

Kurt R Carlson

Ralph A Patterson

Manfred Schiruska

Christine E Geosling

Thomas McLean

Gregory A Zimmerman

Kristin C Cooley

David Barnett Hall

Henry C Abbink

Thomas J Hutchings

David Michael Rozelle

Leo K Lam

Ronald James Michal

Edward Kanegsberg

Robert J Hoover

C Denton Marrs

Lorrie L Gampp

Kenneth W Shafer

Steven C Gillespie

A plurality of voids are introduced into a polymeric material. One or more stress sensitive components in abutment with a portion of the polymeric material are buffered from one or more stresses through employment of the portion of the polymeric material that comprises one or more voids of the plurality of voids. A movement of the portion of the polymeric material is accommodated through compression of one or more of the one or more voids.

Introducing voids into polymeric material for buffering one or more stress sensitive components from one or more stresses

In one example, the voidscomprise one or more gas (e.g., air) bubbles in the solid material. In another example, the voidscomprise a structure that preserves a space in the solid material. In a further example, the voidscomprise hollow elastomeric bubbles, for example, hollow elastomeric microspheres. The hollow elastomeric microspheres comprise microballoons with tin walls that encapsulate a gas to allow for easy compression. For example, the walls of the hollow elastomeric microspheres are strong enough to avoid breakage under pressure, but thin enough to easily compress. In a further example, once cured in the solid material, the hollow elastomeric microspheres comprise substantially similar compressibility characteristics as gas bubbles. The voidsin one example are added to a resin of the solid materialin a substantially uniform distribution. For example, the hollow elastomeric microspheres are stirred into the resin of the solid material

Polymeric material with voids that compress to allow the polymeric material to absorb applied force and decrease reaction force to one or more sensor fibers

An apparatus in one example comprises a buffer layer located on a face that serves as a primary support for an optical fiber winding along a first general direction. The face is coupled with a body that serves as a primary support for the optical fiber winding along a second general direction. The optical fiber winding comprises an optical fiber wound about the body. The buffer layer serves to promote a decrease of one or more strain gradients among a plurality of portions of the optical fiber winding.

Buffer layer promotion of decrease of one or more strain gradients in optical fiber winding

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 bifilar FOG coil winding method employs two identical parallel fibers, each one-half the length of the final FOG coil wound between first and second payout spools so that the respective midpoint of each fiber is located between the two spools. Both parallel fibers are then wound to form a FOG coil using Frigo's quadrupole or dipole winding technique. Prior to winding, one of the payout spools is rotated 180&deg; (degrees) about its fiber pair.

Bifilar fog coil winding pattern with improved shupe bias canceling properties

An Integrated Optics Chip with improved performance when exposed to rapidly changing temperature is disclosed. The optic chip or integrated optic chip or MIOC has a top surface, a +Z face and -Z face. The chip is formed from a crystal having a high electro-optic coefficient such as Lithium Niobate. For the purpose of orienting the components to the optic chip to be described, the +Z crystal axis extends outward from the +Z face. An input waveguide formed in the top surface of the chip and orthogonal to the +Z axis receives an optical signal from an input port, passes the signal via a waveguide network, to an output waveguide coupling the waveguide network to an output port. Metalization is applied to the top face of the optic chip to form at least a first and a second rail. The first and second rails are positioned to very closely straddle a portion of the input waveguide. A conductive bridge connects the first and second rails to prevent a charge differential from developing between the first and second rails.

Dual purpose input electrode structure for MIOCs (multi-function

A system and method for providing scale factor stabilization of a broadband light source used in fiber optic gyroscopes is provided. A primary bandpass filter is positioned in the propagation path of the light emitted by the broadband light source to narrow the spectral width of the optical signal transmitted to the fiber optic gyroscope, which reduces the centroid wavelength shift resulting when the broadband light source is exposed to ionizing radiation and other harsh environmental conditions. The filtered optical signal is then passed through the fiber optic gyroscope, where the filter optical signal is processed to measure the amount of rotation of the fiber optic gyroscope. The scale factor stabilization system further includes the spectral monitor array arranged to perform direct optical wavelength measurements of the filtered optical signal to determine whether a scale factor shift in the optical signal has occurred. When a scale factor shift is detected, the detected scale factor shift is used in a compensation algorithm to correct the scale factor of the optical signal. By monitoring the scale factor shift and adjusting the values measured by the fiber optic gyroscope in accordance with the detected scale factor shift, the accuracy of the fiber optic gyro can be improved to a fraction of a part-per-million.

System and method of stabilizing the scale factor shift in fiber optic

The invention is a focusing polarization rotator for use in the resonant mirror system of a ring laser gyroscope. The focusing polarization rotator accomplishes the traditional task of rotating the plane of polarization of a light beam that passes through it and at the same time performs a focusing function on the light rays. In a resonant mirror system, the device acts to constrain the transverse dimensions of light beams that follow the closed light-beam path established by the resonant mirror system thereby obviating the need for one or more curved mirrors that usually perform this function. The focusing polarization rotator is a wedge-shaped lens made from either a magneto-optic transparent material with a magnetic field within the lens or a material having different indices of refraction for left- and right-circularly-polarized light. The wedge shape of the lens greatly improves the bias stability of the RLG in which it is used.

Apparatus for use in ring laser gyroscopes

Potting compound for fabrication of fiber optic gyro sensor coil and

An integrated optics chip with improved performance when exposed to changing temperature is disclosed. The optic chip or integrated optics chip or MIOC has a top surface, a +Z face and -Z face. The integrated optics chip is formed from a crystal substrate having a high electro-optic coefficient such as Lithium Niobate. For the purpose of orienting the components to the optic chip to be described, the +Z crystal axis extends outward from the +Z face, the Z axis being the axis across which a pyroelectric effect is exhibited. The top surface is orthogonal to the Z axis. An input waveguide on the top surface receives an optical signal from an input port, passes the signal via a waveguide network, to an output waveguide coupling the waveguide network to an output port. A portion of the +Z and -Z faces are coated at least partially with a conductive coating. A conductive path couples the +Z and -Z faces to prevent a charge differential from developing between the +Z and -Z faces due to a change in temperature of the optic chip and the pyroelectric effect.

Integrated optics chip with reduced thermal errors due to pyroelectric

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

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

The invention is a method and apparatus for quantitatively characterizing the pressure-induced nonreciprocity of a fiber-optic coil where the pressure-induced nonreciprocity is a property of a fiber-optic coil which pertains to the degree to which light beams, initially in phase, differ in phase as a result of traversing the fiber-optic coil in reverse directions while the fiber-optic coil is being subjected to a time-varying pressure. The method comprises the steps of applying time-varying pressure to the fiber-optic coil for a predetermined time period, measuring the phase difference of light beams traversing the fiber-optic coil in reverse directions during the predetermined time period, and obtaining a measure of the nonreciprocity of the fiber-optic coil utilizing the measured phase difference. If the time-varying pressure is specified by a first function of time, the measure of the nonreciprocity is the integral over the predetermined time period of the product of a second function of time and either (1) the phase difference of light beams traversing the fiber-optic coil in reverse directions during the predetermined time period or (2) the integral over time of the phase difference. The second function is chosen such that the measure of the nonrecipocity has a signal-to-noise ratio of at least one. Preferably, the second function is (1) an approximation of the time derivative of the first function if the product involves the phase difference or (2) an approximation of the first function if the product involves the integral of the phase difference. The invention also includes the apparatus for practicing the method.

Method and apparatus for determining the pressure-induced nonreciprocity

A fiber optic ribbon is used for forming a sensing coil that may be used in a Sagnac effect fiber optic rotation sensor. The fiber optic ribbon provides a single radial layer per turn of the coil winder and can be made to have a quadrupole spatial turn distribution.

Low shupe bias fiber optic rotation sensor coil

A narrow-band antireflective coating is comprised of a multilayer dielectric film formed on a dielectric substrate. The antireflective coating is initially formed so that its outer layer has a thickness greater than the thickness required for antireflection. The reflectivity is monitored while outer layer is reduced in thickness to reduce the thickness of the outer layer to reduce the reflectivity.

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West Hills, CA, United States of America

John P Rahn