A 3.2-μm wavelength integrated path differential absorption lidar for probing open-path benzene gas

We report on the application of two tunable interband cascade lasers (ICLs) with about 3.2-μm wavelength in integrated-path differential absorption (IPDA) lidar and power-modulation integrated-path differential absorption (PM-IPDA) lidar experiments for probing open-path benzene concentration. To demonstrate the performance of the PM-IPDA lidar, we investigate the performance in an open-path atmosphere according to the comparative experiment of the IPDA lidar and the PM-IPDA lidar. To the best of our knowledge, it is the first comparative experiment of the IPDA lidar and the PM-IPDA lidar in the mid-infrared band for probing open-path benzene concentration. Data from these laboratory experiments indicate the effectiveness of the IPDA lidar and the PM-IPDA lidar, and also that the PM-IPDA lidar can reduce the impact of 1/ f noise on detection performance. Data from these open-path atmosphere experiments with a time resolution of 0.1 s indicate that the detection limit of the IPDA lidar is about 0.89 mg·m -3 and that the detection limit of the PM-IPDA lidar is approximately 0.66 mg·m -3 . Hence the detection limit of the PM-IPDA lidar is approximately 26% lower than that of the IPDA lidar.