Abstract: The present disclosure relates to the technical field of fiber-optic gas sensing and laser photoacoustic spectroscopy, and reliability of a gas detection system is improved by actively selecting a working frequency of low noise interference combined with an optical fiber photoacoustic sensing probe capable of isolating high-frequency noise. A gas enters a photoacoustic microcavity through gaps on a sound-sensitive diaphragm after diffusing into a miniature air chamber through a plurality of micropores. Photoacoustic excitation light is incident into the photoacoustic microcavity through a fiber-optic collimator and then excited to generate a photoacoustic pressure wave to cause the sound-sensitive diaphragm to vibrate periodically. An end face of a single-mode optical fiber and the sound-sensitive diaphragm constitutes a fiber-optic Fabry-Perot interferometer. The interferometer measures a deflection of the diaphragm and inverts a concentration of the to-be-measured gas.

Abstract: The present disclosure relates to the technical field of fiber-optic gas sensing and laser photoacoustic spectroscopy, and reliability of a gas detection system is improved by actively selecting a working frequency of low noise interference combined with an optical fiber photoacoustic sensing probe capable of isolating high-frequency noise. A gas enters a photoacoustic microcavity through gaps on a sound-sensitive diaphragm after diffusing into a miniature air chamber through a plurality of micropores. Photoacoustic excitation light is incident into the photoacoustic microcavity through a fiber-optic collimator and then excited to generate a photoacoustic pressure wave to cause the sound-sensitive diaphragm to vibrate periodically. An end face of a single-mode optical fiber and the sound-sensitive diaphragm constitutes a fiber-optic Fabry-Perot interferometer. The interferometer measures a deflection of the diaphragm and inverts a concentration of the to-be-measured gas.

Abstract: A multifunctional C4F7N/CO2 mixed gas preparation system is disclosed. The C4F7N heat exchanger is used to heat and vaporize C4F7N input through the C4F7N input port; the CO2 heat exchanger is used to heat and vaporize CO2 input through the CO2 input port; the C4F7N/CO2 mixing pipeline structure is used to mix the heated C4F7N and heated CO2, and the C4F7N/CO2 mixed gas output pipeline structure is used to output the C4F7N/CO2 mixed gas. The C4F7N/CO2 mixing pipeline structure comprises a C4F7N/CO2 dynamic gas preparation pipeline structure and a C4F7N/CO2 partial pressure mixing pipeline structure; the C4F7N/CO2 partial pressure mixing pipeline structure includes partial pressure mixing tanks for mixing the CO2 and the heated C4F7N of certain pressures; and a plurality of partial pressure mixing tanks are arranged in parallel. A multifunctional C4F7N/CO2 mixed gas preparation method is also disclosed.