Study on the synchronized measurement technique of two-gas concentration based on digital modulation and demodulation TDLAS

Tunable Diode Laser Absorption Spectroscopy (TDLAS) has revolutionized the field of trace gas detection. Its excellent sensitivity, high resolution, and fast response capability make it applicable to multi-component and multi-parameter measurements. Moreover, it has broad prospects in the field of gas detection. Because of the close relationship between CH4 and CO2 concentrations and seismic activities, accurate monitoring of these two gases' spatial and temporal distribution is of far-reaching significance for earthquake early warning. In this paper, we design a digital modulation and demodulation TDLAS-based dual-gas concentration measurement system to measure CH4 and CO2 gas concentrations simultaneously. Through the design of a single detector with dual light sources, we not only enhance the integration of the system but also eliminate the noise interference caused by the traditional digital phase-locked amplification circuit at the software level, which further improves the accuracy of the TDLAS technology in gas detection and reduces the size and power consumption of the system, which makes it easier for subsequent maintenance and operation. It further improves the accuracy of TDLAS technology in gas detection, reduces the system size and power consumption, and provides a lot of convenience for the subsequent maintenance and optimization work.