High-sensitivity diaphragm type photoacoustic spectrum sensor based on self-mixing

Abstract

The invention relates to a high-sensitivity diaphragm type photoacoustic spectrum sensor based on self-mixing. The high-sensitivity diaphragm type photoacoustic spectrum sensor comprises a sensing light source, an excitation light source, a first coupler, a photoacoustic cavity and a signal processing circuit unit, wherein the sensing light source and the excitation light source emit laser which is led into the photoacoustic cavity through an optical fiber by the first coupler; the photoacoustic cavity comprises a ceramic bushing and a high-sensitivity diaphragm; the laser light source emits the laser to excite gas molecules to generate a photoacoustic signal and enable the high-sensitivity diaphragm to vibrate; the sensing light source serving as a detection light signal is incident into the surface of the high-sensitivity diaphragm and then is reflected back to the end face of the optical fiber; reflected light is output through the optical fiber into a cavity of the sensing light source to generate a self-mixing photoacoustic spectrum signal; the self-mixing photoacoustic spectrum signal is processed through the signal processing circuit unit, so that the vibration frequency and the amplitude of the high-sensitivity diaphragm can be obtained, and the concentration information and the pressure information of the gas can be further obtained. By the adoption of a self-mixing interferential sensing technology, the high-sensitivity diaphragm type photoacoustic spectrum sensor has the advantages that the structure is simple and reliable, and the remote distributed gas detection can be realized.

Description

technical field [0001] The invention relates to a photoacoustic spectrum measurement system, in particular to a self-mixing-based high-sensitivity diaphragm photoacoustic spectrum sensor. Background technique [0002] Photoacoustic spectroscopy has been widely used in environmental monitoring, industrial process control, and medical diagnosis. Photoacoustic gas detection technology is a spectral detection method based on the photoacoustic effect of gas. Its basic principle is to use the gas molecules to be measured to be excited by an external light source, absorb the energy of photons of a specific wavelength, and the gas molecules transition to an excited state, and then pass through The heat releases the absorbed energy, which causes a change in the temperature of the gas to produce a change in pressure. When the excitation light source is modulated with a signal of a certain frequency, the gas will generate an audio signal with the same frequency as the modulation signa...

AI Technical Summary

Problems solved by technology

[0012] However, so far, the principle of laser self-mixing interference using fiber lasers as light sources has not been applied in photoacoustic spectroscopy sensing devices.

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