Research on laser drive circuit for telemetry of combustible gas leakage

In order to ensure the personal safety and production safety of petrochemical enterprises, it is necessary to detect methane combustible gas in production, storage and transportation facilities and give timely alarm. Based on TDLAS telemetry technology, this paper studies the driving circuit of DFB laser with methane gas as the detection target. The external digital to analog converter is controlled by FPGA to generate corresponding sawtooth scan signal and sine wave modulation signal. Among them, the sine wave frequency is 1 kHz-100 kHz, the amplitude is 0-5V, and the sawtooth wave frequency is 1Hz-1kHz, the amplitude is 0-5V. The driver signal generated by the superposition of the scanning signal and the modulated signal is used as the input voltage of the voltage-controlled constant current source to generate the current signal that can drive the laser to emit spectral line. Through the test of the system, the driving current error is less than 0.6%.