Differential absorption lidar

Remote Atmospheric Monitoring.— Several techniques for remote atmospheric monitoring of pollutants, trace gases, etc. by LIDAR (Light Detection And Ranging) have become popular over recent years. Of these, DIAL (Differential Absorption Lidar) spectroscopy would seem to be of most interest to the... 

Differential absorption Lidar mapping of atmospheric atomic mercury in Italian geothermic fields. J Geophys Res 97 3779-3786. 

J.P. Wolf, H.J. Kolsch, P. Rairoux, L. Woste, Remote detection of atmospheric pollutants using differential absorption LIDAR techniques, in Applied Laser Spectroscopy, ed. by W. Demtroder, M. Inguscio (Plenum, New York, 1991), p. 435... 

Browell EV (1989) Differential absorption lidar sensing of ozone. Proceedings of the Institute of Electrical and Electronics Engineers 77 419-432. 

Various methods have been developed for remote gas sensing. These include differential optical-absorption spectroscopy (DOAS), differential absorption lidar (DIAL), and a number of methods that use spectroscopic methods with an atmospheric path in place of a laboratory long-path cell, for example tunable diode laser absorption spectroscopy (TDLAS) and Fourier transform infrared (FTIR) spectroscopy. 

The remainder of this article is devoted to the differential absorption LIDAR or DIAL method that is the most widely used technique for range-resolved remote gas sensing. It relies on elastic scattering from small particles and molecules that are always present in the atmosphere to return the signal. Speciation is achieved using the principle of differential absorption as described below. 

Park CB, Nakane H, Sugimoto N, Matsui I, Sasano Y, Fujinuma Y, Ikeuchi I, Kurokawa J-I, Furuhashi N. 2006. Algorithm improvement and validation of National Institute for Environmental Studies ozone differential absorption LIDAR at the Tsukuba Network for Detection of Stratospheric Change complementary station . Appi. Opt. 45(15) 3561-3576. 

DIAL Differential absorption lidar PES Potential energy surface... 

Due to the coincidence of the CO2 laser lines and the caracteristic absorption spectrum of numerous air pollutant molecules, a tunable CO2 laser is a superior light source for a differential absorption LIDAR. An additional advantage of a tunable CO2 laser is the atmospheric window in the 9-11 pm wavelength range w hich these lasers are capable of utilizing. 

It was planned a field experiment series in which the sensitivity of the two s stems was measured. A 2 m polyethylene foil chamber was used as a gas cell and some free disseminations w re used in the experiments. Sensitivity of the differential absorption lidar systems are charaterized by the minimum detectable path integrated concentration of materials to be detected, their response time and their range. During the field test integration times were 1 sec for all measurements with both VTB-2 and LRS-3 systems. With post processing moving averages were calculated for 10 sec and 30 sec in 1 sec steps. 

For differential-absorption lidars the sensitivity means the lowest value of the measurable path-integrated concentration during the response time. Three groups of factors influence variation of the c 1 value ... 

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