Radiant energy – Photocells; circuits and apparatus – Optical or pre-photocell system
Patent
1982-05-27
1984-12-04
Nelms, David C.
Radiant energy
Photocells; circuits and apparatus
Optical or pre-photocell system
356349, 367149, G02B 514
Patent
active
044866577
ABSTRACT:
A fiber optic acoustic sensing system for tracking a phase shift linearly over a wide range thereby allowing accurate tracking in the presence of temperature induced phase flucuation. In one embodiment, light from a laser is split and coupled into both legs of a fiber interferometer. One leg is phase modulated by the acoustic signal while the other leg is phase modulated by a first and a second piezoelectric cylinder modulators. The second modulator is driven at .omega..sub.m to effectively shift the acoustic information up in frequency into the sidebands of the carrier .omega..sub.m. The light signals in the two legs are combined, detected, cross-correlated with the carrier .omega..sub.m to produce an error signal, and then low pass filtered. This filtered error signal is fed back to control the first modulator. The first modulator keeps the interferometer locked in phase by effectively cancelling out the phase produced by temperature and acoustic pressure flucuations. To effect this cancellation, the first modulator must inversely duplicate the phase shift thereby producing the desired output signal.
REFERENCES:
patent: 3520613 (1970-07-01), Chitayat
patent: 3635562 (1972-01-01), Catherin
patent: 3697887 (1972-10-01), Lee et al.
patent: 4162397 (1979-07-01), Bucaro et al.
patent: 4320475 (1982-03-01), Leclerc et al.
Optical Society of America, Optics Letters, May 1980, vol. 5, No. 5, pp. -175, R. Ulrich, Fiber Optic Rotation Sensing with Low Drift.
Temperature Stabilized Optical Waveguide Modulation, Review of the Electrical Communication Laboratories, vol. 26, Nos. 9-10, 9-10/1978.
Measurement of Sensitivity of Optical Fibers for Acoustic Detection, J. A. Bucaro and T. R. Hickman, Applied Optics, vol. 18, No. 6, 3/15/79.
Fibre Optic Sensors, T. G. Giallorenzi, Optics and Laser Technology, 4/1981.
"Accurate Phase-Measurement System for Fiber-Optic Acoustic Sensor" by Ira Jeffrey Bush, Published in the Proceedings for the ASA Conference in Nov. 1980, Los Angeles.
"Fiber Optic Phase-Swept Phase-Lock Loop" by Jeff Bush, Abstract Distributed at the Mar. 3rd, 1980 Florida Chapter Meeting of the Optical Society of America.
"Acousto-Optic Sensor Development" by J. A. Bucaro and J. H. Cole Reprinted from Oct. EASCON 1979 Record pp. 572-580.
Austin II Ernest
Beers Robert F.
Ellis William T.
Nelms David C.
The United States of America as represented by the Secretary of
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