Photoacoustic spectrometry measuring device and method based on low-coherence optical fiber differential interference non-contact vibration measurement

Abstract

The invention relates to the technical fields of white light interference measurement and gas photoacoustic spectrometry measurement, in particular to a photoacoustic spectrometry measuring device and method based on low-coherence optical fiber differential interference non-contact vibration measurement. The device comprises an ASE light source, a first circulator, a second circulator, a first coupler, a second coupler, a third coupler, a delay optical fiber, a first optical fiber connector, a second optical fiber connector, a ceramic bushing, a high-sensitivity pressure sensitive membrane, a fiber bragg grating with a PZT modulator, a first photoelectric detector, a second photoelectric detector, a third photoelectric detector, a data collecting unit and a computer. The low-coherence light source is adopted, the detection light path is of a Mach-Zehnder and Sagnac mixed interferometer structure, and the three detectors are used for conducting three-way detection modulation on return light. The photoacoustic spectrometry measuring device has the advantages that the device is insensitive to low-frequency disturbance, the measurement dynamic range is large, long-distance non-contact absolute amplitude measurement of optical fiber white light interference can be achieved, light pressure vibration interference is small, and the photoacoustic spectrometry measuring device is not prone to suffer from electromagnetic interference.

Description

technical field [0001] The invention relates to the technical fields of white light interferometry and gas photoacoustic spectroscopy, in particular to a photoacoustic spectroscopy device and method based on low-coherence optical fiber differential interference non-contact vibration measurement. Background technique [0002] Photoacoustic spectroscopy gas detection technology originated in 1880. In the early days, it was limited by low-power light sources and low-sensitivity acoustic detection tools. The development of technology was limited. Since the 1960s, thanks to the advent of lasers and the development of high-sensitivity detection tools, Photoacoustic spectroscopy technology has entered a stage of rapid development. The high power of the laser itself, good directional monochromaticity and other advantages effectively enhance the intensity of the photoacoustic spectrum signal and improve the detection sensitivity; The diversity of acoustic spectroscopy technology has...

AI Technical Summary

Problems solved by technology

[0004] 1. Light intensity modulation brings light pressure vibration interference, which affects signal demodulation results;

[0005] 2. Most photoacoustic spectroscopy sound transmission systems use electrodynamic and capacitive microphones. Electric microphones are susceptible to electromagnetic interference and have large noise, which affects signal demodulation results.

In some modulation and demodulation techniques, like classical heterodyne demodulation, pseudo-heterodyne demodulation, synthetic heterodyne and PGC (Phase Generated Carrier) demodulation techniques, an additional modulation element is required, and the dynamic range of the measurement system is limited by Modulation frequency limitation

[0013] The present invention intends to use a low-coherence optical fiber differential interferometer and a passive demodulation algorithm for three-way detection to perform gas photoacoustic spectrum measurement to solve the above problems. No patents and documents have been found about the disclosure of this measurement method

Images