Detection system of photoacoustic spectrometry gas in fiber laser device cavity

Abstract

The invention discloses a detection system of photoacoustic spectrometry gas in a fiber laser device cavity, and belongs to the technical field of optical fiber gas detection. The detection system comprises a pump light source, a wavelength division multiplexer and a computer. The annular fiber laser device cavity is jointly composed of the wavelength division multiplexer, rare earth doped fibers, an opto-isolator, a gas chamber, a tunable filter and an optical fiber coupler, wherein an input coupling mirror and an output coupling mirror are placed in the gas chamber; a quartz tuning fork is placed in the proper position in the gas chamber and is used for probing acoustic wave signals generated by laser excitation gas in the fiber laser device cavity; the signals probed by the quartz tuning fork are further exacted by a lock-in amplifier, are acquired by a data collection card and are transmitted to the computer, and after gas concentration inversion is conducted on the signals, gas concentration information is acquired. Combined with the optical fiber laser technology and the photoacoustic spectrometry gas detection technology, the detection system of the photoacoustic spectrometry gas in the fiber laser device cavity has the advantages of being high in sensitivity and cost performance, very low in cost and the like.

Description

technical field [0001] The invention relates to a photoacoustic spectrum gas detection system in a fiber laser cavity, in particular to an inner cavity gas detection system based on photoacoustic spectrum gas detection technology, which belongs to the technical field of fiber optic gas detection. Background technique [0002] In the process of industrial production, qualitative or even quantitative analysis of certain gases is often required to ensure production safety. For some trace gases, high-sensitivity gas detection devices are required. At present, the commonly used gas detection methods mainly include electrochemical methods, infrared spectroscopy, and gas chromatography. Among them, infrared spectroscopy has always attracted much attention, and its key technologies include direct Spectral absorption technology, differential absorption technology, differential absorption technology based on wavelength scanning, harmonic detection technology, intracavity spectral abso...

AI Technical Summary

Problems solved by technology

The traditional absorption technology has a limited detection sensitivity due to the limited effective absorption path of gas; the intracavity spectral absorption technology places the gas chamber in the resonant cavity of the fiber laser, and uses the laser to and fro to greatly increase the effective absorption path of the gas. However, this technology still relies on wavelength scanning technology, which needs to extract extremely weak effective signals in strong background noise, which limits the improvement of detection sensitivity; photoacoustic spectroscopy detection technology directly measures the light energy absorbed by gas, which can detect extremely weak absorption , has high sensitivity, but the existing research is based on the laser coupled out of the finished laser as the excitation light source, and a large part of the light energy is lost in the coupling process

[0003] "China Laser", 2009, Volume 36, Issue 9, Pages 2384-2387, the authors are Jia Dagong, Liu Kun, Jing Wencai, Wang Yan, Zhang Hongxia, Zhang Yimo, entitled "Gas Detection Method Based on Ring Cavity Fiber Laser" This article proposes a gas detection system based on the design of the fiber laser cavity. The system uses wavelength scanning technology to make the output wavelength of the fiber laser cover multiple gas absorption peaks. Compared with the use of a single absorption peak, this method has improved detection sensitivity and accuracy. However, direct spectral absorption based on wavelength scanning technology itself has the defect of low sensitivity, and the traditional gas chamber is not able to increase the effective absorption of light. Generally, its size will not be too small, which will cause the disadvantage of large volume when forming products in the future

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