A high-precision design of vertical-cavity surface-emitting laser driving circuit and temperature control circuit of coal mine oxygen detection

A high-precision driving circuit and temperature control circuit of vertical-cavity surface-emitting laser(VCSEL) controlled by soft startting switching circuit was designed based on GD32F303RCT6 microcontroller and ADN8834 thermoelectric cooling controller.In the driving circuit, the microcontroller generates binary data superposition by high frequency sine wave signal and low frequency sawteeth signal.This is converted into high precision VCSEL driving current signal by signal generation circuit and voltage-current conversion circuit.In the temperature control circuit, the proportional integral differential(PID) compensation circuit and digital to analog converter(DAC) target temperature control circuit was designed to realize automatic laser temperature adjustment.The results show that, at first, the current output range is from 0.680 mA to 1.360 mA.The frequency error of sawtooth wave is less than 0.5%, and the frequency error of sine wave is less than 0.1%.The scanning accuracy of oxygen absorption peak is up to 0.07 pm, and the corresponding scanning accuracy of current is 0.12 μA.The temperature control accuracy of the temperature control circuit is ±0.012 ℃.The tunable diode laser absorption spectroscopy(TDLAS) for oxygen detection in coal mines meet the application requirements.