Fiber bragg grating hydrophone based on balance static pressure of spiral tube

Abstract

The invention relates to a fiber bragg grating hydrophone and particularly a fiber bragg grating hydrophone based on the balance static pressure of a spiral tube. The fiber bragg grating hydrophone comprises a cylindrical rigid cylinder with an opening at one end. The fiber bragg grating hydrophone is characterized in that the opening end of the rigid cylinder is provided with a sound-sensitive diaphragm and is connected with an end cover, a sound transmission window is formed in the side wall of the end cover, and an elastic compensation body close to the sound-sensitive diaphragm is mountedon the inner wall of the rigid cylinder; a fiber bragg grating is installed at the internal axis of the rigid cylinder, one end of the fiber bragg grating is connected with the sound-sensitive diaphragm, and the other end of the fiber bragg grating is connected with the closed end of the rigid cylinder; and a communicating hole is formed in the side wall of the rigid cylinder, the spiral tube is installed in the rigid cylinder, the opening of one end of the spiral tube is connected with the outer side of the rigid cylinder through the communicating hole, and the opening of the other end of thespiral tube is located in the rigid cylinder. According to the fiber bragg grating hydrophone of the invention, high dynamic sensitivity and static pressure balance are realized in the small-sized hydrophone; the length of the tube is increased in an effective space; the high-pass cut-off frequency of the hydrophone is reduced; the low-frequency bandwidth of the hydrophone is expanded; and the reliability of the hydrophone is greatly improved.

Description

[0001] (1) Technical field [0002] The invention relates to an optical fiber hydrophone, in particular to an optical fiber grating hydrophone based on a spiral tube balancing static pressure. [0003] (2) Background technology [0004] Optical fiber hydrophone is an instrument that detects sound in water by using the light transmission characteristics of optical fiber and the modulation effect generated by the sound pressure of the surrounding environment. Compared with traditional electromagnetic hydrophones, optical fiber hydrophones have the following advantages: high sound pressure sensitivity, no electromagnetic interference, small size, waterproof and corrosion resistance, and both sensing and transmission. It has good application prospects in resource exploration, underwater navigation, marine defense and other fields. [0005] At present, the main technical solutions of fiber optic hydrophones include intensity modulation type, interference type, fiber grating type, e...

AI Technical Summary

Problems solved by technology

[0012] (1) Complex structure, bulky volume, limited working water depth, and low reliability. For example, in the scheme proposed by Steven Goodman, the volume of the airbag is large, which is not conducive to the miniaturization of the hydrophone structure and affects practicality; the volume of the airbag is the cavity of the hydrophone When the volume is 5 times, the theoretical maximum water depth is only 50m; the airbag is large and easily damaged;

[0013] (2) The contradiction between balancing static pressure and maintaining high dynamic sensitivity, such as the scheme proposed by Zhang Wentao et al. When the hydrostatic pressure is large enough to completely fill the cavity with water, due to the incompressibility of water, the piston will It is difficult to deform under the action, and the sensitivity and amplitude-frequency characteristics will deteriorate; there are long holes in the side wall of the hydrophone support tube, and the fiber grating is exposed to the external fluid and is easily damaged;

[0014] (3) Low-frequency characteristics. The hydrophone’s balanced static pressure is characterized by high-pass filtering in terms of response characteristics. Therefore, the sensitivity is reduced in the frequency band below the high-pass cut-off frequency. The detection ability of extremely low-frequency underwater acoustic signals and infrasound signals is insufficient. How to reduce High-pass cut-off frequency, to extend the low-frequency frequency range, is a technical problem that needs to be solved

Images