All-fiber double-gas synchronous detection photoacoustic spectrometry system based on passive tuning fork and detection method thereof

Abstract

The invention discloses an all-fiber double-gas synchronous detection photoacoustic spectrometry system based on a passive tuning fork. The system comprises an excitation laser module, the passive tuning fork, a gas chamber, an optical fiber micro-vibration sensing module and a gas information analysis module, wherein the passive tuning fork is arranged in the gas chamber, and the gas chamber is filled with a to-be-detected gas containing a target gas 1 and a target gas 2. Two lasers with different wavelengths are utilized to synchronously excite two anti-phase resonance modes with the lowest frequency of the passive tuning fork, and each vibration mode detects one gas, so that double-gas synchronous detection is realized; a vibration signal of the passive tuning fork is picked up by detecting the phase change of interference light output by the two optical fiber interferometers, a photoacoustic signal generated by the action of excitation laser and trace gas is recovered, and then a second harmonic signal is extracted; and the all-fiber double-gas synchronous detection photoacoustic spectrometry system has the advantages of high sensitivity, small size, easiness in networking, noise resistance, uncharged front end, intrinsic safety, electromagnetic interference resistance, high temperature resistance and the like, and is suitable for various trace gas measurement scenes.nd.

Description

technical field [0001] The invention belongs to the technical field of photoacoustic spectroscopy, and more specifically, the present invention relates to a photoacoustic spectroscopy system and a detection method thereof based on a passive tuning fork-based all-fiber dual-gas synchronous detection photoacoustic spectroscopy system. 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 t...

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 gas molecular relaxation rate

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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