Design of single-laser remote methane gas measurement system with distance measurement based on time-division multiplexing technology

Limited to the principle of Tunable Diode Laser Absorption Spectroscopy (TDLAS) technology, the existing open-path laser remote methane measurement system can only measure the integral concentration, and it needs to be matched with a laser rangefinder to complete the calculation of the average concentration, which increases the complexity of the system. To solve this problem, by driving the laser diode (LD) in time-division multiplexing mode, we complete the integral concentration of gas and distance measurement with the use of a single LD. We complete the design of the laser signal transceiver structure and finish the corresponding hardware circuit design, including the LD driving circuit, frequency generation, mixer circuit, and optoelectronic signal receiving circuit. The experiment shows the measurement error of the system is less than 2.5% while measuring the average concentration in the case of different concentrations and distances, and the system greatly reduces the system complexity while satisfying the performance requirements.