Bragg grating temperature/strain fiber sensor having combination

Abstract

An arrangement for simultaneous optical determination of temperature and strain fluctuations in an optical fiber for precisely determining the changes in environmental influences and/or fiber loads is disclosed. The arrangement performs two different measurement tasks of the absolute measurement of a stationary quantity, such as temperature and the relative, high-resolution measurement of quickly varying quantities of fluctuation processes with comparable accuracy in a single optical The arrangement which is achieved using a spectrometer with an imaging, spectrally dispersive element, a first input light bundle being arranged with reference to the dispersive element such that the light spectrally dispersed at the dispersive element is projected onto a first linear receiver The arrangement, and an additional second input light bundle is directed onto the dispersive element in the spectrometer, whose spectrally dispersed light falls onto a second linear receiver The arrangement, parallel to the first one, the two input light bundles are fed light from a broadband light source which has been reflected by at least two optical fiber gratings with different mean wavelengths, and an interferometer The arrangement with phase modulation and different arm lengths is present at least in the light path of the second input light bundle upstream of the spectral dispersion by means of the dispersive element, whose evaluation is performed via the second receiver. The arrangement by means of phase modulation modules with reference to relative changes in the Bragg wavelengths, while a CCD evaluation module for determining the absolute Bragg wavelengths of the optical fiber gratings is arranged downstream of the first receiver The arrangement.