Coherence multiplexing of optical sensors

Details Coherence multiplexing of optical sensors Coherence multiplexing of optical sensors

1987-11-17

1989-01-24

Westin, Edward P.

Optics: measuring and testing

By particle light scattering

With photocell detection

250227, 350 9614, G01B 902

Patent

active

047997974

ABSTRACT:
A multiplexed optical sensor system comprising a short coherence length source (SLD 60), a plurality of waveguide sensors (62, 64), a corresponding plurality of waveguide detectors (68, 70), and a common optical bus 84. Each sensor comprises a sensor interferometer having sensing and reference arms, each arm comprising an optical waveguide. Means are provided for varying the optical path length of the sensing arm based on a sensed input parameter. In one preferred embodiment, the detection subsystem comprises a plurality of detectors, each comprising a photodetector and a detector interferometer having first and second arms. The arms of each sensor interferometer (i) have an optical path length difference LS(i) that is greater than the coherence length of the SLD, and that differs from the path length difference LS(j) of each other sensor interferometer by an amount greater than the coherence length of the SLD. Each detector has a path length difference LD(i) that differs from the path length difference of an associated sensor LS(i) by not substantially more than the coherence length of the SLD. Thus variation of each sensed input parameter produces an amplitude variation in the output of a corresponding detector. An embodiment comprising a single swept detector interferometer is also disclosed.

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