Optics: measuring and testing – By particle light scattering – With photocell detection
Patent
1982-09-29
1985-07-23
Willis, Davis L.
Optics: measuring and testing
By particle light scattering
With photocell detection
73657, 250227, 350 9615, 356346, 356352, G01B 902
Patent
active
045306036
ABSTRACT:
A fiber optic sensor comprises a length of optical fiber, forming a loop, and a fiber optic directional coupler for optically closing the loop. The loop and coupler form a resonant cavity for light circulating therethrough. A PZT cylinder, about which the fiber loop is wrapped, is utilized to control the total round trip phase delay of the circulating light, and thus, control the intensity of the optical output signal. The phase delay is adjusted to a point where the optical output signal is at maximum sensitivity to changes in phase. When the fiber loop is exposed to, e.g., acoustic waves, the loop length changes correspondingly, thereby causing the phase delay, and thus, the optical output signal to vary. By detecting variations in output signal intensity, the frequency and intensity of the acoustic waves may be determined. The sensor also includes a feedback system for stabilizing the fiber loop against low frequency thermal drift.
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Chodorow Marvin
Shaw Herbert J.
Stokes Loren F.
Koren Matthew W.
The Board of Trustees of Leland Stanford Jr. Univ.
Willis Davis L.
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