Spectral decoding in fiber-optic interferometric sensor.

Principles of white-light interferometric techniques are described in this paper. Different spectral decoding methods applied to low coherence interferometry are also presented. Among them one can distinguish: direct recovering of an optical path difference with use of second interferometr as a spectrum analyzing device several wavelength interrogation with is a spectrometer or suitable narrow-band optical filters, and chromatic monitoring in wider spectrum. The last decoding mrthod was applied to test the performance of fiber optic interferometric pressure and temperature sensor. a diffraction grating was used to monitor a wide part of the output spectrum. The phase shift induced by measured changes in both sensor was determined with a fringe counting method.