High-sensitivity wide-frequency-response all fiber microseism monitoring system

Abstract

The invention relates to a high-sensitivity wide-frequency-response all fiber microseism monitoring system, and belongs to the fields of fiber sensing and safety monitoring. The system is composed of a laser light source, a fiber coupler, a sensing probe and a signal demodulator; the sensing probe comprises a packaging casing, a top cover, the fiber coupler, a reference arm fiber, a sensing arm fiber as well as a sensing arm energy transducer, a mass block, a reference arm energy transducer, a pad, a nut, a reference arm reflector and a sensing arm reflector positioned in the middle of the bottom of the packaging casing and fixedly connected in the concentric upward way; the sensing probe is filled with oil liquid; and the magnitude of a stress applied to the pad is adjusted via the nut. The system has the advantages including high detection sensitivity, smooth frequency response curve, intrinsic safety and wide application range, can obtain microseism signal of lower magnitude and wider frequency band without damage, and is suitable for safety monitoring for different types of mines and infrastructures.

Description

technical field [0001] The invention relates to the fields of optical fiber sensing and safety monitoring, in particular to an all-fiber microseismic monitoring system with high sensitivity and wide frequency response. Background technique [0002] Since the 1960s, many major mining countries have successively developed mine microseismic monitoring equipment and monitoring systems. For example, Canadian ESG, South African ISS, and Polish SOS systems have carried out applications in the field of microseismic monitoring applications. The front ends of the above systems are all based on piezoelectric or electromagnetic sensors, which are not intrinsically safe, and are not suitable for complex environments such as strong electromagnetic, high temperature and high humidity in coal mines. The paper "A Fiber Bragg Grating Acceleration Sensing System" [Ma Liangzhu, Chang Jun, Liu Xiaohui, Huo Dianheng, Liu Tongyu. Shandong Science, 2008, 06:19-22] discloses a fiber Bragg grating ac...

AI Technical Summary

Problems solved by technology

The front ends of the above systems are all based on piezoelectric or electromagnetic sensors, which are not intrinsically safe, and are not suitable for complex environments such as strong electromagnetic, high temperature and high humidity in coal mines

The paper "A Fiber Bragg Grating Acceleration Sensing System" [Ma Liangzhu, Chang Jun, Liu Xiaohui, Huo Dianheng, Liu Tongyu. Shandong Science, 2008, 06:19-22] discloses a fiber Bragg grating acceleration sensing system with a bandwidth of 2-100Hz , the minimum resolution is only 0.1mg, but it cannot be applied to the monitoring of hard rock environments such as metal mines; the patent application with the publication number of CN106940387A discloses a Michelson interferometric fiber optic acceleration sensor, which uses a differential fiber Michelson interferometer Detect the phase change caused by the displacement of the mass block, and demodulate the acceleration change of the sensor in real time, but the structure is complicated; the patent application with the publication number CN105158508A discloses a new type of optical fiber micro-vibration acceleration sensor with a simple structure, which is squeezed by a cantilever beam The sensing fiber is slightly deformed under the excitation of the vibration signal, and the reflected optical power at the end of the fiber is modulated by the vibration signal. The structure is simple, but the detection sensitivity is low due to the narrow frequency band

[0003] To sum up, the front end of the traditional microseismic monitoring system needs power supply, which is not intrinsically safe. There is a risk of explosion in the coal mine environment, and the sensitivity is low and the frequency band is narrow, so it is impossible to achieve fidelity pickup of microseismic signals.

However, although the microseismic monitor based on the principle of fiber grating is intrinsically safe, its key technical indicators such as working frequency band and resolution are poor, making it difficult to be practical.

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