A gas detection method and device based on software phase-locked cavity subtraction phase-shift spectroscopy

Abstract

The invention discloses a cavity attenuated phase shift spectroscopic detection method and device for gas based on software phase locking. The device comprises an LED, a temperature control module, anoptical component, a gas circuit component and an electric circuit component, wherein the electric circuit component comprises a photodetector, an LED driver, a data acquisition card and a computer;the optical component comprises a plano-convex lens, an optical resonant cavity, a high-reflectivity mirror and an interference filter; and the gas circuit component comprises a three-way gas valve, amass flowmeter, a gas filter, and a sampling pump. The detection method comprises the following steps: generating a driving signal; modulating an LED light source; emitting modulated light through the optical resonant cavity, converting an optical signal into a voltage signal by the photodetector, acquiring the voltage signal by using the data acquisition card and inputting the voltage signal into the computer; and carrying out software phase locking amplification and filtering to demodulate the concentration of gas to be detected. The detection method and device of the invention can speed upan operation speed, reduce system noise and improve detection precision, sensitivity and stability, and is capable of continuously carrying out sampling and convenient to carry.

Description

technical field [0001] The invention belongs to the technical field of atmospheric component detection, relates to cavity attenuation phase shift spectrum gas detection, in particular to a cavity subtractive phase shift spectrum gas detection method and device based on software phase lock. Background technique [0002] At present, there are many types of air pollutants, which can be summarized into gaseous pollutants and aerosol state pollutants according to their existing state. There are many types of gaseous pollutants, which are mainly divided into five aspects: SO 2 Main sulfur compounds, NO and NO 2 Mainly nitrogen-containing compounds, hydrocarbons, carbon oxides and halogen compounds. Air pollution is extremely harmful to human health. Long-term exposure to low concentrations of pollutants can cause bronchitis, lung cancer, etc., and high concentrations can cause acute poisoning and even death. Air pollution is also very harmful to plants. Under high concentration...

AI Technical Summary

Problems solved by technology

At present, the realization of CAPS technology at home and abroad is to build a modulation lock-in system through arbitrary waveform generators and lock-in amplifiers, but there are defects: the lock-in amplifiers and arbitrary waveform generators are bulky, making the whole set of instruments inconvenient to carry

However, the purchase of lock-in amplifiers needs to be imported from overseas, which is greatly restricted by relevant policies.

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