FP interference type sound wave detector and sound wave detection method

Abstract

The invention discloses an FP interference type sound wave detector and a sound wave detection method, and belongs to the technical field of sound wave detection, and the FP interference type sound wave detector comprises a light source, an optical fiber circulator, an FP sensing head, a spectrum real-time acquisition module and a signal processing demodulation module. The FP sensing head is composed of an optical fiber collimator, a ceramic ferrule, a metal sleeve and a thin film, and the optical fiber collimator is designed to a certain extent. By using the improved Fourier phase demodulation algorithm, the spectral phase variation in direct proportion to the cavity length variation can be obtained, and the improved demodulation algorithm greatly widens the dynamic range of the detection system. For an extrinsic high-fineness FP sensor, the phase demodulation method provided by the invention can realize phase multiplication by performing Fourier phase demodulation at a high-order characteristic frequency peak on a Fourier spectrum of a spectrum, so that the phase sensitivity of the sensor is improved.

Description

technical field [0001] The invention belongs to the technical field of sound wave detection, and more particularly, relates to an FP interference type sound wave detector and a sound wave detection method. Background technique [0002] Acoustic detection technology has broad application prospects in infrastructure, medical and health, national defense and military, disaster warning and other fields. At present, the practical acoustic wave detectors are mainly capacitive and piezoelectric electric acoustic wave detectors. Although this type of electrical sensor has a simple structure and a good sensitivity, it has great application limitations in environments such as strong electromagnetic, flammable and explosive, and long-distance transmission. [0003] The fiber optic acoustic wave sensor is anti-electromagnetic interference, easy to miniaturize, high sensitivity, anti-electromagnetic interference, easy to multiplex networking, and avoids many problems of electrical senso...

AI Technical Summary

Problems solved by technology

The phase carrier generation and demodulation method needs to generate a strict carrier, and the demodulation algorithm is relatively complicated; the 3×3 coupler method needs to use a 3×3 coupler, and it is necessary to strictly control the coupling ratio of 1:1:1 and the phase difference of each output terminal is 120°; the improved 3×3 coupling method needs to cooperate with algorithms such as ellipse fitting, which can relax the requirements for coupling ratio and phase difference, but the demodulation of small signals is very limited

For the spectrum demodulation algorithm, the interferometric phase is obtained by calculating the interference spectrum of the interferometer, which has the advantages of high precision, strong anti-interference, and little influence by system noise. It is suitable for demodulating low-frequency signals, but involves the calculation of the reverse calculation phase steps, often introduces the problem of phase jumps

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