Quartz tuning fork strengthened photoacoustic spectroscopy gas sensor based on acoustic resonator

Abstract

The invention discloses a quartz tuning fork strengthened photoacoustic spectroscopy gas sensor based on an acoustic resonator. The gas sensor comprises a laser (1), a focusing lens (5), a tubular resonator, a quartz tuning fork (11), a function generator (15) electrically connected with the laser (1) and a lock-in amplifier (14) electrically connected with the quartz tuning fork (11), wherein the focusing lens (5) and the tubular resonator are arranged on an optical path (2) of the laser (1); the function generator (15) is electrically connected with the lock-in amplifier (14); the tubular resonator is the acoustic resonator (9) with a slit (91) in the middle; the length of the acoustic resonator is not more than 10mm, the external diameter is not more than 1mm and the internal diameter is not more than 0.6mm; the width of the slit (91) is not more than 0.2mm and the length is not more than the internal diameter of the acoustic resonator (9); prongs (111) of the quartz tuning fork (11) are positioned on the slit (91) and the distances between the prongs (111) and the slit (91) are not less than 0.001mm. The gas sensor has simple structure, small volume and strong anti-jamming property, works stably, is convenient to adjust and use and can be extensively used for detecting the components or contents of the gases.

Description

technical field [0001] The invention relates to a gas sensing device, in particular to a quartz tuning fork enhanced photoacoustic spectrum gas sensing device based on an acoustic resonant cavity. Background technique [0002] With the continuous development of economy and society, environmental problems have become increasingly prominent. In order to effectively monitor and predict environmental pollution, people have made unremitting efforts to detect the composition or content of substances through photoacoustic spectroscopy, as in the US patent specification US2005 / 0117155A1 announced on June 2, 2005 A "quartz-enhanced photoacoustic spectroscopy device" mentioned. It intends to provide a photoacoustic spectroscopy device using a quartz tuning fork to detect the composition or content of gaseous substances. It consists of a laser and a focusing lens, a tubular resonant cavity, and a quartz tuning fork on its optical path, and the input of the laser is electrically conne...

AI Technical Summary

Problems solved by technology

However, there are deficiencies in this device. First, in order to form resonance, the optical path, that is, the laser beam must pass through two thin tubes and the tuning fork incision of the quartz tuning fork, and the width of the tuning fork incision is generally only 0.2 to 0.3mm. Therefore, the laser The beam quality of the source must be very good, that is, the focused spot must be able to pass through the tuning fork cutout of the quartz tuning fork, which not only increases the difficulty of device adjustment, but also increases the manufacturing cost and use cost of the device; secondly, it is used for resonance enhancement There is a quartz tuning fork between the two thin tubes of the signal, and there is a gap between the quartz tuning fork and the two thin tubes, so that the acoustic resonance condition is not fully satisfied, which greatly reduces the effect of resonance enhancement; again, the tuning fork cutout of the quartz tuning fork It greatly limits the inner diameter of the thin tubes added on both sides. The larger the inner diameter of the tube, the smaller the enhancement effect, but the small inner diameter of the tube brings great complexity to the arrangement of the laser beam. The laser beam must strictly pass through the The center of the two thin tubes and the center of the tuning fork cutout of the quartz tuning fork, if the laser beam hits the tube wall of the thin tube or one arm of the quartz tuning fork, it will cause noise, and the laser beam deviates from the center of the tuning fork cutout of the quartz tuning fork It will also greatly reduce the strength of the resonance signal

Images