Interface configuration for rate sensor apparatus
First Claim
1. A rate sensor for use in inertial reference systems to detect angular rotations and measure magnitudes and directional sense of the rates of angular rotations, said rate sensor comprising:
- optical source means for generating an incoming optical source wave signal having a predetermined wave length;
at least one gyroscope channel comprising;
an optical fiber ring;
optics circuit means for splitting said source wave signal into a pair of counter-propagating optical waves, and for recombining said counter-propagating optical waves into an outgoing wave signal wherein resultant fringe patterns are representative of the relative phases of said counter-propagating waves; and
optical path means for interconnecting said optical source means, said optics circuit means, and said optical fiber ring so as to apply said incoming optical source wave signal to said optics circuit means, to apply said counter-propagating optical waves through said optical fiber ring and to apply said counter-propagating optical waves emerging from said optical fiber ring back to said optics circuit means;
detection circuit means connected to said gyroscope channel for generating an intensity signal indicative at least in part of said resultant fringe patterns; and
signal processing means connected to said detection circuit means and responsive to said intensity signal for generating output signals corresponding at least in part to said rate of angular rotation;
characterized in that said optical path means further comprises;
first path means comprising at least in part a pair of first optical waveguides, each of said pair of first optical waveguides having substantially identical first indices of refraction and forming a first plane;
second path means comprising at least in part a pair of second optical waveguides, each of said pair of second optical waveguides having substantially identical second indices of refraction different from said first indices of refraction; and
said second pair of optical waveguides is coupled to said first pair of optical waveguides so that a boundary formed between said first and said second pairs of optical waveguides is angled within said first plane and relative to a plane passing transversely through longitudinal axes of each of said first pair of optical waveguides.
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Accused Products
Abstract
An optical rate sensor apparatus (300) measures rates of angular rotation along a plurality of orthogonal axes. The apparatus (300) comprises a passive ring Sagnac interferometric arrangement having a light source circuit (308) and a series of multi-turn fiber optic rings (302, 304, 306). An optics/modulator circuit (312) selectively switches optical waves emitted from the light source circuit (308) into gyroscope channels and transmits the signals through fiber optic rings as counter-propagating optical waves. The optics/modulator circuit (312) also recombines the optical waves after they emerge from the corresponding rings. The optics/modulator circuit (312) includes optical components integrated onto an integrated optics chip (IOC) consisting substantially of lithium niobate. Optical fibers (606, 608) are coupled from the rings (302, 304, 306) to the integrated optics chip. To reduce bias error effects of reflections, the interface (610) between the optical fibers and the integrated optics chip is angled in the plane of the interferometer. Also, the angled interface (610) creates a path length difference greater than the coherence length of the reflections traversing the IOC optical paths between the interface (610) and circuitry which recombines optical waves on the IOC paths.
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Citations
21 Claims
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1. A rate sensor for use in inertial reference systems to detect angular rotations and measure magnitudes and directional sense of the rates of angular rotations, said rate sensor comprising:
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optical source means for generating an incoming optical source wave signal having a predetermined wave length; at least one gyroscope channel comprising; an optical fiber ring; optics circuit means for splitting said source wave signal into a pair of counter-propagating optical waves, and for recombining said counter-propagating optical waves into an outgoing wave signal wherein resultant fringe patterns are representative of the relative phases of said counter-propagating waves; and optical path means for interconnecting said optical source means, said optics circuit means, and said optical fiber ring so as to apply said incoming optical source wave signal to said optics circuit means, to apply said counter-propagating optical waves through said optical fiber ring and to apply said counter-propagating optical waves emerging from said optical fiber ring back to said optics circuit means; detection circuit means connected to said gyroscope channel for generating an intensity signal indicative at least in part of said resultant fringe patterns; and signal processing means connected to said detection circuit means and responsive to said intensity signal for generating output signals corresponding at least in part to said rate of angular rotation; characterized in that said optical path means further comprises; first path means comprising at least in part a pair of first optical waveguides, each of said pair of first optical waveguides having substantially identical first indices of refraction and forming a first plane; second path means comprising at least in part a pair of second optical waveguides, each of said pair of second optical waveguides having substantially identical second indices of refraction different from said first indices of refraction; and said second pair of optical waveguides is coupled to said first pair of optical waveguides so that a boundary formed between said first and said second pairs of optical waveguides is angled within said first plane and relative to a plane passing transversely through longitudinal axes of each of said first pair of optical waveguides. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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16. A rate sensor for use in inertial reference systems to detect angular rotations and measure magnitudes and directional sense of the rates of angular rotation, said rate sensor comprising:
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optical source means for generating an incoming optical source wave signal having a predetermined nominal wavelength; at least one gyroscope channel comprising; a passive ring path having first and second ends; splitting means for splitting said source wave signal into a pair of counter-propagating optical waves; optical path means for applying said counter-propagating optical waves through said associated ring path, wherein said counter-propagating optical waves emerge therefrom with a relative Sagnac phase shift indicative of the rate of angular rotation of said ring path; and combining means for recombining said counter-propagating waves into an outgoing optical wave signal, wherein the resultant low order fringe pattern is representative of the relative phases of said counter-propagating waves; detection circuit means connected to said gyroscope channel for generating an intensity signal indicative of said resulting low order fringe pattern; and signal processing means connected to said detection circuit means and responsive to said intensity signal for generating output signals corresponding to said rates of angular rotation; characterized in that said optical path means comprises; a first optical waveguide coupled to an optical path emerging from said splitting means, and having a first path length; a second optical waveguide coupled to another optical path emerging from said splitting means, said second optical waveguide being substantially parallel to said first optical waveguide and having a second path length, and forming a first plane with said first optical waveguide; a third optical waveguide coupled between said first optical waveguide and said first end of said passive ring path; a fourth optical waveguide coupled between said second optical waveguide and said second end of said passive ring path, and positioned substantially parallel to said third optical waveguide; and a boundary formed by interfaces between said first and third optical waveguides, and between said second and fourth optical waveguides, is angled within said first plane relative to a plane passing transversely through longitudinal axes of said first optical waveguide and said second optical waveguide. - View Dependent Claims (17, 18, 19, 20, 21)
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Specification