Demodulation device and demodulation method of double-path quadrature phase optical fiber acoustic vibration sensor

Abstract

The invention discloses a demodulation device and a demodulation method of a double-path quadrature phase optical fiber acoustic vibration sensor. According to the demodulation method, a light signalemitted by a light source (1) enters the optical fiber acoustic vibration sensor (3) through an optical fiber circulator (2), an external vibration signal causes vibration of a diaphragm of the optical fiber acoustic vibration sensor (3), and a modulated light signal is returned and divided into two signals through an optical fiber coupler (4); the two signals enter a birefringent crystal (6) through a double-path polarizer (5) to become two signals with a quadrature phase; the two signals are analyzed through a double-path analyzer (7); detection of the two optical signals is performed through a double-path photoelectric detector (8); a digital collection card (9) is adopted to perform signal collection; and cavity length change information is obtained finally after processing. Through the demodulation device and the demodulation method, effective demodulation of the optical fiber acoustic vibration sensor is realized, and the defects of previous relevant demodulation methods are overcome; and demodulation of high-frequency acoustic signals can be realized, the two signals with the stable quadrature phase are created, and the precision of a measurement result is guaranteed.

Description

technical field [0001] The invention belongs to the field of optical fiber sensing, in particular to a demodulation device and a demodulation method for a dual-path orthogonal phase optical fiber acoustic vibration sensor based on birefringent crystals and polarization technology. Background technique [0002] The fiber optic acoustic vibration sensor consists of the fiber end face and the diaphragm end face to form a Fabry-Perot microresonator cavity. sensing. The traditional demodulation device and method to the optical fiber acoustic vibration sensor include: 1) utilize single light source to realize the intensity demodulation method to the optical fiber acoustic vibration sensor, the shortcoming is that this method requires the working interval of the optical fiber acoustic vibration sensor cavity length Harsh, poor stability; 2) The phase demodulation method of the optical fiber acoustic vibration sensor using a single light source and phase digital carrier (PGC) metho...

AI Technical Summary

Problems solved by technology

The traditional demodulation device and method to the optical fiber acoustic vibration sensor include: 1) utilize single light source to realize the intensity demodulation method to the optical fiber acoustic vibration sensor, the shortcoming is that this method requires the working interval of the optical fiber acoustic vibration sensor cavity length Harsh, poor stability; 2) The phase demodulation method of the optical fiber acoustic vibration sensor using a single light source and phase digital carrier (PGC) method, the disadvantage is that the demodulation speed of this method is easily limited, and it is only suitable for the solution of low frequency signals 3) Using dual tunable monochromatic light sources to realize the demodulation of the optical fiber acoustic vibration sensor, the disadvantage is that this method uses the central wavelength value of the two light sources and the calculation relationship between the optical fiber acoustic vibration sensor cavity length to realize the quadrature phase, which is vulnerable to The drift of the light source and the movement of the cavity length cause the phase relationship to be non-orthogonal and cause large errors in measurement

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