Optics: measuring and testing – By particle light scattering – With photocell detection
Patent
1983-02-01
1985-11-12
Evans, F. L.
Optics: measuring and testing
By particle light scattering
With photocell detection
250227, 356349, G01B 902
Patent
active
045524572
ABSTRACT:
A fiber optic interferometric physical sensor. A fiber optical Mach-Zehnder interferometer includes a sensor arm and a reference arm having different optical path lengths. A transducer coupled to the sensor arm modulates the phase of light signals passing therethrough in response to a physical quantity. The interferometer is supplied with an input optical signal which includes light components at two different wavelengths. The detected intensity of the output of the interferometer includes two components, each of which vary in relation to the physical quantity. Each output component is related to one of the two optical input wavelengths. The two output components differ in phase by an amount proportional to the path length difference between the sensor and reference arms and proportional to the wavelength difference between the light components of the input optical signal. The phase difference is adjusted such that the sensitivities of the two output components to the physical quantity are never simultaneously at a minimum. In an alternative embodiment, a single laser having a continuously variable wavelength is used with the interferometer having differing sensor and reference path lengths to achieve maximum sensitivity.
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Giallorenzi Thomas G.
Sheem Sang K.
Taylor Henry F.
Beers Robert F.
Ellis William T.
Evans F. L.
Forrest John L.
Koren Matthew W.
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