Double-tube side-by-side type quartz tuning-fork enhancing type photoacoustic spectrometry detection apparatus

Abstract

A double-tube side-by-side type quartz tuning-fork enhancing type photoacoustic spectrometry detection apparatus comprises a laser, a focusing lens, a collimating lens, a gas sample pool, a lock-in amplifier, a laser controller, a function generator, a control hose, a frequency tracking controller, and a preamplifier electrically connected with a quartz tuning fork output terminal. Two same optical paths are respectively subjected to collimation and focusing, then enter miniature tubes, are focused at the focus at the central parts of the miniature tubes, and respectively generate opto-acoustic signals. The gas sample pool is provided with a mounting base, two miniature tubes are symmetrically arranged at the sidewalls of the mounting base, the quartz tuning fork is arranged at the bottom of the mounting base, and the tuning fork arm of the quartz tuning fork is parallel to or perpendicular to the miniature tubes. The central position of each miniature tube is provided with a slit corresponding to a notch or the tuning fork arm of the quartz tuning fork, and when working, the quartz tuning fork is subjected to the sound pressure effect of the miniature tubes at two sides at the same time, and the signal intensity is enhanced. The apparatus also is provided with a constant-temperature water hole at the bottom of the mounting base for keeping quartz tuning fork properties stable.

Description

technical field [0001] The invention relates to a gas detection device, in particular to a gas photoacoustic spectrum detection device based on a quartz tuning fork enhanced type. Background technique [0002] Gas detection technology has a wide range of applications in industrial production and daily life, such as leak detection of oil and gas pipelines, detection of dissolved gases in transformer oil in power systems, detection of exhaust gases from chemical companies, and detection of trace pollutant gases in the air, Exhaled gas detection in human diseases and medical diagnosis, etc. [0003] The US invention patent US2005 / 0117155A1 published in 2005 mentions a "quartz enhanced photoacoustic spectroscopy device". A photoacoustic spectroscopy device using a quartz tuning fork to detect the composition or content of gaseous substances. The device is composed of a laser, a focusing lens, a tubular resonant cavity, a quartz tuning fork, a control device for the laser, an o...

AI Technical Summary

Problems solved by technology

Its shortcoming is that 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 very small, which puts forward high requirements on the quality of the laser light source; at the same time, the two thin tubes The axis of the axis is consistent with the opening direction of the tuning fork notch of the spaced quartz tuning fork, so that the acoustic resonance condition is not fully satisfied, which reduces the effect of resonance enhancement; at the same time, for the case of helium as the carrier gas, the length of the two thin tubes is very large, making the beam It is very difficult to pass the tuning fork cutout without touching the tube wall and the tuning fork; again, the cutout of the quartz tuning fork greatly limits the inner diameter of the two thin tubes. Arrangement of the laser beam presents great complexity

This method also has shortcomings, that is, it can only detect gas components using a certain fixed carrier gas, which is not conducive to the formation of a universal instrument. In addition, if the quartz tuning fork is contaminated and the resonance frequency shifts, the tubular resonator cannot resonate. reduced stability

There is a document "Experimental Study of Quartz-Enhanced Photoacoustic Spectroscopy Based on Miniature Non-resonant Cavities for Helium Purity Analysis" (Acta Physica, Vol.62, No.7(2013)) proposed to use two microtubes, whose structure is similar to that of the patent US2005 / 0117155A1 is similar, but the length of the tube is too small to form a resonant cavity, and the microtube only serves to limit the diffusion of the columnar symmetrical pressure wave generated by the target gas

However, because there is no resonant cavity in this method, there is a problem of low signal strength.

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