Passive tuning fork resonance enhanced all-optical fiber three-gas detection photoacoustic spectrometry system and detection method thereof

Abstract

The invention discloses a passive tuning fork resonance enhanced all-optical fiber three-gas detection photoacoustic spectrometry system, wherein the system comprises an excitation laser module, a passive tuning fork and a target gas chamber; the excitation laser module generates three specified wavelength lasers at specified modulation frequencies; target gas and laser act in the gas chamber to generate sound wave signals with three frequencies, and after resonance of the sound wave signals is enhanced, the passive tuning fork generates anti-phase resonance with different resonance frequencies, so that the distance between the interference type optical fiber sensing module and a passive tuning fork vibration arm is changed; the interference type optical fiber sensing module collects interference light phase difference change caused by the distance change; and a gas information analysis module extracts three second harmonic signals corresponding to modulation frequencies from the phase difference change so as to obtain the concentration information of three target gases, and has the advantages of high sensitivity, small size, uncharged front end, intrinsic safety, electromagnetic interference resistance, high temperature resistance and the like.

Description

technical field [0001] The invention belongs to the technical field of photoacoustic spectroscopy, and more specifically, the invention relates to a passive tuning fork resonance-enhanced all-fiber three-gas detection photoacoustic spectroscopy system and a detection method thereof. Background technique [0002] Multi-gas online measurement has important applications in the fields of environmental monitoring, industrial control, agricultural production, bioengineering and medical diagnosis. Quartz-enhanced photoacoustic spectroscopy is an indirect absorption spectroscopy technique, which has many advantages: compact shape and low cost; no photodetector is used, and the excitation laser wavelength is not limited; the detection sensitivity has little to do with the interaction length of light and the sample, Rather, it is directly proportional to laser power and acoustic sensor sensitivity; the zero-background feature allows the amplifier to operate over a large dynamic range ...

AI Technical Summary

Problems solved by technology

Quartz-enhanced photoacoustic spectroscopy using a custom-made low-frequency quartz tuning fork enables simultaneous detection of dual gases using the fundamental frequency and the first overtone frequency, but the first overtone frequency is usually relatively high and does not match the relaxation rate of the gas molecules

At the same time, whether a commercial standard quartz tuning fork (32.768kHz) or a custom-made quartz tuning fork is used, quartz-enhanced photoacoustic spectroscopy requires low-noise preamplification of the weak piezoelectric current, which cannot be applied to strong electromagnetic interference, high temperature, and flammable and explosive and other special environments

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