Automatic Gain Control Method Based on Tunable Diode Laser Used for Ambient Trace-Gas Monitoring

Tunable diode laser absorption spectroscopy (TDLAS) is a new method to detect trace-gas qualitatively or quantificationally based on the scan characteristic of the diode laser to obtain the absorption spectroscopy in the characteristic absorption region. It needs to combine with a long absorption path in the ambient trace-gas measurements. In this paper, we study the influences of the light-intensity of detector fluctuation on system performance, adopt the normalized light intensity to eliminate the influences on the measurement by light intensity, and design the hardware circuit for self-scheduled adjusting light intensity to improve the detection performance of the whole system. The measurement error is less than 2% by adopting this design.