Scanning laser interference type fiber optic acoustic phase-locked detection system and scanning laser interference type fiber optic acoustic phase-locked detection method

Abstract

The invention provides a scanning laser interference type fiber optic acoustic phase-locked detection system and a scanning laser interference type fiber optic acoustic phase-locked detection method,which belong to the technical field of trace gas detection. The system comprises a photoacoustic excitation light source, a light modulator, a photoacoustic cell, a fiber optic microphone, a broad-band scanning laser source, a fiber optic circulator, a high-speed wavelength query module, a phase-locked loop, a square-wave signal generator, a digital signal processor, and a computer. By carrying out synchronous wavelength scanning control and synchronous spectrum sampling control on the broad-band scanning laser source and the high-speed wavelength query module and combining the Fabry-Perot cavity length high-speed synchronous demodulation technique based on a fiber optic scanning laser interferometer with the phase-locked amplification technique, the invention realizes high sensitivity andhighly stable detection on weak photoacoustic signals. The invention can greatly increase the precision and limit sensitivity of photoacoustic spectrometry-based trace gas detection, and provides a highly competitive technical solution for photoacoustic spectrometry-based trace gas detection.

Description

Technical field [0001] The invention belongs to the technical field of trace gas detection, and relates to a scanning laser interference type optical fiber acoustic wave phase-locked detection system and method. Background technique [0002] Photoacoustic spectroscopy trace gas detection technology has significant advantages such as high sensitivity and small sampling volume. It has shown wide applications in the fields of environmental pollution gas monitoring, dissolved gas analysis in transformer oil, and coal mine flammable and explosive gas monitoring. prospect. [0003] In the photoacoustic spectroscopy measurement, the gas molecules in the gas cell absorb light energy and undergo a non-radiative transition to produce a heat change, which causes the gas to vibrate and generate sound waves. For the detection of very low concentrations of trace gases, the photoacoustic signal is usually only in the micropascal level. According to the principle of photoacoustic spectroscopy, t...

AI Technical Summary

Problems solved by technology

[0004] The object of the present invention is to propose a scanning laser interference optical fiber acoustic wave phase-locked detection system and method for photoacoustic spectroscopy, aiming to solve the photoacoustic problems existing in the all-optical photoacoustic spectrometer based on fiber optic Fabry-Perot microphones. Poor signal demodulation stability and low precision, etc., further improve the detection sensitivity of trace gas detection, and expand a larger space for the application of photoacoustic spectroscopy in trace gas detection

Images