A calibration-free laser photoacoustic spectroscopy trace gas detection instrument and method

Abstract

The invention provides a calibration-free laser photoacoustic spectrum trace gas detection instrument and method, belonging to the technical field of trace gas detection. The laser photoacoustic spectrum trace gas detection instrument includes a laser light source, an optical collimator, a photoacoustic cell, a photothermal conversion element, a microphone, an inlet valve, an outlet valve, a light source driver, a signal acquisition and processing circuit and an industrial computer. A photothermal conversion element is added to the traditional gas absorption photoacoustic cell, and the generated solid photoacoustic signal is used as a reference signal, and the wavelength modulation technology and 2f / 1f detection method are used to measure the gas concentration, so as to realize the immunity under the power change of the laser light source. Calibration gas concentration measurement. The invention fully utilizes the advantages of the small gas production rate of the photoacoustic spectrum and the calibration-free measurement of the tunable diode laser absorption spectrum, and greatly improves the reliability of the gas concentration measurement of the laser photoacoustic spectroscopy system. The invention provides a highly competitive technical solution for detecting trace gas with high sensitivity and high reliability.

Description

technical field [0001] The invention belongs to the technical field of trace gas detection, and relates to a calibration-free laser photoacoustic spectrum trace gas detection instrument and method. Background technique [0002] Laser absorption spectroscopy trace gas detection technology, with its advantages of high sensitivity, high selectivity and long working life, has been used in power device fault characteristic gas analysis, industrial production emission monitoring, coal mine flammable and explosive gas monitoring and medical respiratory gas diagnosis. played an important role in other applications. [0003] Since the infrared spectral region is the characteristic absorption band of some gas molecules, the concentration of the gas to be measured can be measured by using the corresponding laser light source. Tunable diode laser absorption spectroscopy (TDLAS) and laser photoacoustic spectroscopy are the most common methods for gas detection using this principle, but ...

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Problems solved by technology

[0006] The purpose of the present invention is to propose a calibration-free laser photoacoustic spectroscopy trace gas detection instrument and method, aiming at solving the problem of increasing gas concentration measurement errors caused by changes in laser light source power existing in laser photoacoustic spectroscopy trace gas detection instruments problems, to expand more space for the application of laser photoacoustic spectroscopy in the field of trace gas detection

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