Optical: systems and elements – Deflection using a moving element – Using a periodically moving element
Reexamination Certificate
1998-07-29
2001-04-03
Chan, Jason (Department: 2633)
Optical: systems and elements
Deflection using a moving element
Using a periodically moving element
C359S199200, C359S199200, C359S199200, C359S199200, C359S199200, C385S024000, C324S612000, C340S870020, C340S870030
Reexamination Certificate
active
06211982
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates generally to remote measurement of electrical current. More particularly, this invention relates to techniques for measuring electrical current at a one location and using optical signals output from an interferometer to signals indicative of the electrical current to another location for processing.
Prior art for sensing electrical current with optical telemetry includes utilizing a step-down transformer connected to a fiber-wrapped PZT phase modulator through a resistor, with the fiber comprising one leg of a fiber optic Michelson interferometer. Prior art also includes use of Bragg gratings, in changing the spectrum of light telemetered light from the current sensor, as well as fiber optic sensors that make use of the Faraday effect, which change the polarization state of light propagating through an optical fiber in proportion to a magnetic field. These methods tend to be costly to implement and environmentally sensitive, especially when the interferometer is comprised of optical fiber.
SUMMARY OF THE INVENTION
This invention provides a novel method for remote measurement of a quantity such as electrical current. The present invention provides a low cost, stable solution to the problem of high accuracy current sensing over large distances, with a large number of sensors. It integrates an innovative approach to voltage-to-optical phase conversion with existing technology for current-to-voltage conversion, as well as telemetry and signal processing suitable for high channel count. It allows a single chip interferometer with zero pathlength mismatch between interferometer branches to be used with a low cost source and detection approach for high channel counts. Additionally, the signal processing approach affords minimal environmental, thermal and vibration sensitivity.
A system for measuring electrical current flowing in an electrical conductor comprising a signal source/detection module and a telemetry optical fiber having a first end optically coupled to the signal source/detection module. A conversion module is optically coupled to a second end of the telemetry optical fiber. The conversion module includes an interferometer having a pair of optical paths and an optical waveguide arranged to be included in one of the optical paths of the interferometer. The interferometer is arranged to produce an interference pattern to indicate the phase relationship of optical signals input to the pair of optical paths from the signal source/detection module. The system also includes apparatus arranged to phase modulate optical signals guided by the optical waveguide and an electrical current sensor connected to the phase modulating apparatus and arranged to provide a modulating signal to the phase modulating apparatus such that the interference pattern indicates the magnitude of the electrical current.
The electrical current sensor head produces a voltage having a magnitude that is proportional to the electrical current amplitude. The conversion module includes apparatus for producing an encoded digital signal that indicates the magnitude of the electrical current.
The interferometer preferably includes an integrated optics substrate with the pair of optical paths of the interferometer formed on the substrate. The phase modulating apparatus preferably includes a pattern of electrodes formed on the integrated optics substrate and arranged in relation to the optical paths so that application of an electrical signal to the electrodes produces a corresponding phase difference between optical signals traversing the optical paths of the interferometer.
An appreciation of the objectives of the present invention and a more complete understanding of its structure and method of operation may be had by studying the following description of the preferred embodiment and by referring to the accompanying drawings.
REFERENCES:
patent: 4370612 (1983-01-01), Puech et al.
patent: 4577414 (1986-03-01), Milgiori et al.
patent: 4857727 (1989-08-01), Lenz et al.
patent: 4871223 (1989-10-01), Auracher et al.
patent: 4899042 (1990-02-01), Falk et al.
patent: 4915503 (1990-04-01), Pavlath
patent: 4929830 (1990-05-01), Bonhert et al.
patent: 4999539 (1991-03-01), Coovert et al.
patent: 5041779 (1991-08-01), Hales
patent: 5053694 (1991-10-01), Bonhert et al.
patent: 5060225 (1991-10-01), Godfrey
patent: 5210407 (1993-05-01), Ito et al.
patent: 5239401 (1993-08-01), Olshansky
patent: 5267336 (1993-11-01), Sriram et al.
patent: 5278499 (1994-01-01), Ito et al.
patent: 5317929 (1994-06-01), Brown et al.
patent: 5369485 (1994-11-01), Hofler et al.
patent: 5434501 (1995-07-01), Esman et al.
patent: 5479094 (1995-12-01), Esman et al.
patent: 5583637 (1996-12-01), Tokano et al.
patent: 5587791 (1996-12-01), Belleville et al.
patent: 5623561 (1997-04-01), Hartman
patent: 5731579 (1998-03-01), Woods
patent: 5987195 (1999-11-01), Blake
“Two low-cost robust electro-optic hybrid current sensors capable of operation at exteremely high potential” Rev. Sci Instrum. 63 (12) Dec. 1992, Ning et al., pp. 5771-5773.
“Interrogation of a conventional current transformer by a fiber-optic interferometer” Optics Letters vol. 16, No.18, Sep. 15, 1991, Ning et al., pp. 1448-1450.
Goldner Eric L.
Hall David B.
Chan Jason
Litton Systems Inc.
Lynn & Lynn
Patel Sanjay
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