Patent ID: 6744035
Filing Date: 2004-06-01
Classification: G01K,G02B,H04B

Abstract:
A passive, temperature compensated tunable filter calibration device in a Bragg-grating interrogation system comprised of:a calibration and reference device further comprised of an array of Bragg gratings bonded to a first host substrate and a single grating bonded to a second host substrate having a different linear coefficient of thermal expansion from that of the first host substrate; a plurality of gratings contained in an optical fiber forming a sensing array; a filter for filtering a broadband optical light so that at any point in time only a narrow band of light is present in the gratings containing fibers connected to the filter; a power source for applying a predetermined drive voltage to the scanning filter to produce a scanning filter control voltage; a first photodetector for receiving optical light reflected back from the calibration and reference device and converting the optical light to an electrical signal; a second photodetector for receiving light reflected from the sensing array an converting it to an electrical signal; amplifiers associated with each electrical signal amplifying the electrical signal representing the reflected light so as to show a series of peaks corresponding to the gratings in the array from the lowest to the highest wavelength as the drive voltage is increased; and processing electronics for receiving the amplified electrical signals and calculating a voltage-to-wavelength function for the scanning range of the filter.