Application of atmosphere sensing by infrared lidars for environmental protection and industry needs

Abstract

The paper analyses some equipment and methodological aspects of atmospheric pollution monitoring by infrared lidars. Features of optical parametric oscillators (including our created two-stage system) operating in the spectral ranges of molecular fundamental vibrations are discussed. The environment protection and industry demands for this remote monitoring technology are considered. Despite the progress in the technology and low detection limits achieved, the reliable and fast identification of pollutants is far from perfection. Inner and outer factors worsening the lidar performance, i. e. stability of the transmitted pulse energy, atmospheric turbulence, and irregularity of the pollutant plume near the source, are examined. A lidaric measurement model implying pulse stability was developed and applied to the 8–14 μm and 0.5 mJ per pulse lidar operating in the topographic target mode with the 0.05 m2 telescope and the mercury cadmium telluride detector. It has been found that the laser pulse energy instability (energy dispersion parameter D) essentially worsens the detection limit in shorter ranges (<2 km for D=1%). Adaptation of lidar technology to the fast varying irregular plumes was tested experimentally. Plume detection events were processed using the probabilistic model, and the probability of false alarm was evaluated. Keywords: IR lidar, atmospheric pollution monitoring, optical parametric oscillator, modelling