Method and apparatus for compensating fiber optic lead and connector losses in a fiber optic sensor.

摘要

Optical sensor apparatus comprises an optical source (10) for projecting a broadband source light beam including spectral components having different wavelengths through a fibre optic cable (12); a polarizer (14) for polarizing the source light beam; multiple wave retardation means (18) for retarding the different wavelength components to provide a light beam having a plurality of retarded components; an optical transducer (20) for receiving the retarded light beam and modulating the retarded components in accordance with an externally applied condition, each retarded component being modulated by an amount corresponding to its wavelength; an analyzer (22) for receiving the output from the transducer (20) and providing analyzed components corresponding to the modulated components, the total light intensity of said analyzed light beam remaining unresponsive to the externally applied condiution; a filter (34) for receiving a first portion (30) of the analyzed light beam to provide a first optical signal having only one part of the analyzed components including an analyzed component that varies according to the externally applied conditions, while a second portion (32) of the analyzed light beam provides a second optical signal including the plurality of analyzed components; photodetectors (36,40) for receiving the first and second optical signals and converting them respectively into a first electrical signal corresponding to an intensity of said first optical signal, and a second electrical signal corresponding to the intensity of the second optical signal; and processing means (38) for converting the first and second electrical signals into an output signal corresponding to the ratio of the first to the second electrical signals.