Method and device for detecting underwater acoustic signal with coherent laser remote sense

Abstract

A method and device for coherent laser remote sensing detection of underwater acoustic signals, the method is to divide single-frequency laser light into detection light and reference light, and the detection light is emitted to the water surface after optical heterodyning; the sound waves emitted by the underwater instrument make the water surface Forced vibration is formed, and the vibration frequency and amplitude are consistent with the frequency and intensity of the underwater sound wave; the frequency of the reflected light of the probe light on the water surface is modulated by the forced vibration vibration speed of the water surface, and the reflected light is coherent with the reference light, which is detected by the photoelectric The vibration velocity of the water surface is demodulated by the electric heterodyne demodulator, and then the waveform of the underwater sound wave is obtained to realize the detection of the underwater sound signal. The invention has the advantages of high sensitivity, long distance measurement, flexible optical path, reliable structure and easy adjustment.

Description

technical field [0001] The invention relates to laser remote sensing, in particular to a method and device for detecting underwater acoustic signals by coherent laser remote sensing, which realizes long-distance and non-contact detection of underwater acoustic signals, and can be used as a wireless, neutral The receiving end of the long-distance communication of the relay device. Background technique [0002] Due to the different characteristic impedance of water and air, most of the underwater sound waves are reflected at the interface, and the loss of sound waves penetrating to the water surface is very large. In order to detect underwater sound signals, the receiving transducer must be immersed in water, and then detected The acoustic signal is transmitted to the underwater platform by cable or radio. This detection method with wet end relays limits the mobility of the underwater platform to detect underwater acoustic signals. In order to overcome this problem, a method ...

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Problems solved by technology

[0005] (1) The detection sensitivity is proportional to the cosine value cos(θ) of the laser incident angle, when the laser incident angle is small, the detection sensitivity is greatly reduced

For long-distance detection of underwater acoustic signals, it is difficult to achieve large-angle measurement, so this method cannot achieve long-distance detection

[0006] (2) The angles of transmitter and receiver must be strictly matched, and it is difficult to adjust the optical path

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