Fiber F-P sensor cavity length wavelet phase extraction demodulation method

Abstract

The invention provides a fiber F-P sensor cavity length wavelet phase extraction demodulation method. At first, the interference spectrum is calculated by means of a fast fourier transform algorithm to obtain a cavity length value to be a cavity length rough measuring value; the searching scope of a scale factor is determined by taking the 2-3 times of the precision of the fast fourier transform algorithm as the radius, and the phase information corresponding to each point in the interference spectrum is solved by continuous complex wavelet transform; and the cavity length value of the fiber F-P sensor is calculated by the linear gradient obtained by the linear fitting phase and wavenumber to be the final cavity length value. The absolute measurement of the F-P sensor cavity length can be achieved, so that the high-precision and high-resolution measurement of physical quantity can be achieved.

Description

technical field

[0001] The invention belongs to the technical field of optical fiber sensing, and in particular relates to a method for extracting and demodulating the phase of an optical fiber F-P sensor cavity with long wavelets. Background technique

[0002] According to the modulation type of its parameters, fiber optic sensors can be divided into intensity modulation type, polarization state modulation type, phase modulation type and wavelength modulation type. Intensity-modulated optical fiber sensors are widely used in general engineering because of their simple structure and fast response. Polarization modulation and phase modulation optical fiber sensors are widely used in the detection of physical quantities such as strain, temperature, pressure and magnetic field because of their high measurement accuracy. The most common wavelength modulation sensor is the Fiber Bragg Grating (FBG) sensor. This type of sensor is widely used in various occasions due to its simple...

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