Non-resonant photoacoustic spectroscopy system

Abstract

The invention discloses a non-resonant photoacoustic spectrometry system, and belongs to the technical field of gas detection. The non-resonant photoacoustic spectrometry system comprises an infraredwide-spectrum light source, a reflecting cover, a modulation and filtering unit, a photoacoustic cell and a microphone; the photoacoustic cell is of an amplified structure, the diameter of the cross section of a cavity of the photoacoustic cell is increased in the light direction, and the photoacoustic cell comprises a front window and a rear window. The reflecting cover is used for reflecting andconverging the light rays emitted by the infrared wide-spectrum light source to the center of the rear window. When the wide-spectrum light source is placed at the left focal point, light can be effectively gathered at the center of a rear window of the photoacoustic cell, the gathering effect can be optimized under the condition that good light beam collimation is kept, the overall spatial distribution of light beams is reasonable, and the power of the light beams entering the photoacoustic cell is improved; the amplification proportion of the amplified photoacoustic cell is matched with theshape parameters of the reflecting cover, so that the distribution and proportion of light rays emitted to the inner wall of the photoacoustic cell by light beams are reduced to the maximum extent, the same-frequency noise caused by light absorption of the cell wall is reduced, and the signal-to-noise ratio and the detection limit of the system are improved.

Description

technical field [0001] The invention belongs to the technical field of gas detection, and more specifically relates to a non-resonant photoacoustic spectroscopy system. Background technique [0002] Photoacoustic spectroscopy is a spectroscopic technique based on the photoacoustic effect. In the photoacoustic effect, gas molecules absorb infrared light of a specific wavelength and are excited to a high-energy state. The molecules in the high-energy state convert the absorbed light to After the energy is converted into heat energy, it returns to a low-energy state. When the frequency of the incident light is modulated, the heat energy will show the same periodic change as the modulation frequency to generate sound waves. The sound signal is detected by the microphone and the final concentration of the gas is calculated. . [0003] According to the working mode, photoacoustic spectroscopy gas detection system is divided into two types: resonant type and non-resonant type. Th...

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Problems solved by technology

[0005] Aiming at the defects of the prior art, the purpose of the present invention is to provide a non-resonant photoacoustic spectroscopy system, which aims to solve the problem of large same-frequency noise in the existing non-resonant photoacoustic spectroscopy system

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