Sensitivity of coherent rage-resolved differential absorption lidar

Abstract

A range-resolved DIAL (differential absorption lidar) system with heterodyne detection has been developed. A hybrid TEA CO2 laser was employed as the transmitter oscillator, which emitted single-frequency pulses of 140 mJ. The heterodyne receiver, which had a minimum detectable power of 2 × 10−11 W, could detect the echo signals backscattered from atmospheric aerosols at a 5-km or greater range. The system sensitivity to the target gas, defined as the product of the minimum detectable concentration and the difference in the absorption coefficients, was experimentally found to be 3.7 × 10−4 m−1 for a range resolution of 300 m after averaging over fifty backscattered signals.