Detection instrument and method for reinforced laser photoacoustic spectrometry of small-sized multi-reflection photoacoustic cell

Abstract

The invention relates to a detection instrument and method for a reinforced laser photoacoustic spectrometry of a small-sized multi-reflection photoacoustic cell, which belongs to the technical fieldof trace gas detection. The detection instrument comprises a laser light source, a light source drive, an optical collimator, a small-sized multi-reflection photoacoustic cell, an air inlet valve, anair outlet valve, a microphone, a signal acquisition and processing circuit and a touch screen. The wavelength modulation is performed for the laser light source, and the laser is reflected for multiple times on the wall surface of the small-sized multi-reflection photoacoustic cell along a radial direction. By adopting a secondary resonant detection technology, the interference of a fundamental-frequency photoacoustic signal generated by a solid photoacoustic effect due to the multiple reflection on the wall surface can be eliminated, and the background-free and high-sensitivity detection fortrace gas can be realized. By adopting the small-sized multi-reflection photoacoustic cell in the detection instrument, while the capacity in the cell can be reduced, the active power of the photoacoustic exciting light can be greatly increased by virtue of the multiple reflection of the laser on the inner wall, so that the requirement on the gas sample amount can be reduced, and the detection sensitivity and stability of the system can be improved.

Description

technical field [0001] The invention belongs to the technical field of trace gas detection, and relates to a detection instrument and method of a miniaturized multiple reflection photoacoustic pool enhanced laser photoacoustic spectrum. Background technique [0002] With its advantages of high sensitivity and small sampling volume, the photoacoustic spectroscopy trace gas detection instrument has been widely used in power device fault characteristic gas analysis, industrial production ultra-low emission monitoring, standard gas impurity detection, coal mine flammable and explosive gas monitoring and medical science. It plays an important role in applications such as respiratory gas diagnosis. [0003] According to the principle of photoacoustic spectroscopy, the sensitivity of gas concentration measurement is proportional to the effective power of the photoacoustic excitation light source. Therefore, improving the effective power is the key to high-sensitivity photoacoustic ...

AI Technical Summary

Problems solved by technology

At present, the multi-reflection absorption cell used in photoacoustic spectroscopy has a large volume, and the work stability is not high

However, due to the small amount of gas samples in application fields such as gas analysis of power device fault characteristics and off-line monitoring of flammable and explosive gases in coal mines, the volume of the gas chamber is required to be as small as possible, but the small cross-sectional area of ​​the photoacoustic cell reduces the thermal damping time. The amplitude of the photoacoustic pressure wave is attenuated, thereby reducing the sensitivity of the photoacoustic spectroscopy trace gas detection system

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