Gas sensor based on photoacoustic spectrometry

Abstract

The invention discloses a gas sensor based on photoacoustic spectrometry, comprising a circuit matched and connected with a light source (1) and a quartz tuning fork (13). The gas sensor is characterized in that an acoustic resonator (6) is composed of a main tube (11) with a branch tube (12) which are communicated with each other vertically; the tube axis of the main tube (11) is coaxial with a light path (2), the tube length of the main tube (11) is 4.57-7.87 mm, and the tube inner diameter of the main tube (11) is 0.4-1.5mm; the tube length of the branch tube (12) is 1-2mm and the tube inner diameter of the branch tube (12) is 0.4-0.5mm; the focus of a focusing lens (4) is located at the communicated part of the main tube (11) and the branch tube (12); the plane and the slit centre of a tuning fork arm (131) of the quartz tuning fork (13) are vertical to and located in the axis of the branch tube (12) respectively, and the distance between the plane of the tuning fork arm (131) and the tail port of the branch tube (12) is 20-50mu m; and the slit width of the tuning fork arm (131) of the quartz tuning fork (13) is 0.28-0.32mm, and the resonant frequency of the tuning fork arm (131) of the quartz tuning fork (13) is 31.768-33.768kHz. The gas sensor based on photoacoustic spectrometry realizes coupling between a light-excited acoustic energy and the quartz tuning fork with the highest efficiency and can be used for the field of trace gas detection.

Description

technical field [0001] The invention relates to a gas sensor, in particular to a photoacoustic spectrum gas sensor. Background technique [0002] Sensors that detect and determine trace gas content have a wide range of application requirements in the fields of environmental monitoring, industrial process control, and medical diagnosis. Based on the above factors, people have made unremitting efforts to obtain such sensors. A Chinese invention patent application document CN 101813621A of the applicant on August 25, 2010 described a "quartz tuning fork enhanced photoacoustic spectroscopy gas sensing device based on an acoustic resonant cavity". The gas sensing device consists of a focusing lens on the optical path of the light source, a tubular acoustic resonant cavity whose cavity axis is coaxial with the optical path, a quartz tuning fork placed at the side opening slit of the resonant cavity, and a circuit that is connected with the light source and the quartz tuning fork. ...

AI Technical Summary

Problems solved by technology

However, this gas sensing device has shortcomings: because the opening slit of the tubular acoustic resonator in its radial direction is difficult to completely match with the quartz tuning fork, the coupling between the light-excited acoustic wave energy and the tuning fork cannot be realized with maximum efficiency. Therefore, the energy of the photoacoustic absorption signal cannot be effectively utilized

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