Detection device and detection method for semiconductor laser self-mixing infrasound

Abstract

The invention discloses a detection device for semiconductor laser self-mixing infrasound. The detection device comprises a semiconductor laser in which a photoelectric detector is packaged, a laser adjusting rack, a collimating lens, a convergent lens, a sensitive reflecting film, a laser driving circuit, a signal pre-processing circuit, a sound card, a data processing unit and an output terminal, wherein the sensitive reflecting film is arranged in an infrasound sound field zone; light generated by the semiconductor laser passes through the collimating lens to form parallel light; the parallel light is converged to the surface of a diaphragm through the convergent lens; part of light is reflected back to the inside of a laser cavity by adjusting the laser adjusting rack and is self mixed with the light generated in the laser cavity; the self-mixing light intensity is detected by the photoelectric detector and is converted into a voltage signal; the voltage signal is converted into a digital signal by the sound card; and the digital signal is processed by the data processing unit to output the measuring result. The detection device disclosed by the invention dispenses with auxiliary optical elements such as a spectrometer and a reference mirror of a traditional laser interferometer, and has compact and simple structure, low requirement on the processing precision of the device, low manufacturing cost and simplexes in operation.

Description

technical field [0001] The invention belongs to the field of infrasonic wave detection, and in particular relates to an infrasonic wave detection device and a detection method for detecting infrasonic waves by using laser self-mixing interference to measure diaphragm vibration. Background technique [0002] Infrasound is a sound with a frequency below 20 Hz, which cannot be heard by the human ear. Many activities in nature, such as volcanic eruptions, earthquakes, typhoons, rocket launches, waves beating, and wheel driving, all have infrasound. At present, detection devices for detecting infrasound waves are generally capacitive infrasound sensors, fiber optic infrasound sensors, and double-beam interference infrasound sensors. [0003] However, the above detection devices all have their shortcomings. Among them, for the capacitive infrasound sensor, its shortcomings are: it requires fine structure, strict design, strict material selection, especially very high processing ...

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Problems solved by technology

[0003] Yet above-mentioned detection device all has its weak point

Among them, for the capacitive infrasound sensor, its shortcomings are: it requires fine structure, strict design, strict material selection, especially very high processing accuracy, and its main parts require ultra-finishing.

Moreover, this type of electrical parameter sensor has relatively poor anti-electromagnetic interference ability, which limits its application, such as being limited to earthquake monitoring, and the market price is high; for fiber-optic infrasound sensors, its disadvantages are: High technical requirements and low cost performance; for the double-beam interferometric infrasonic sensor, its disadvantage is that it needs more auxiliary optical components, such as spectrometers, polarizers, reference mirrors, etc., and the optical path needs to be strictly controlled. Ground collimation, difficult to adjust

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