This review aims to show the techniques of lidar in atmospheric remote
sensing, which can be utilized to draw three-dimensional maps of pollutants
distribution over path lengths of the order of few kilometers. The detection
limits achieve values o
f the order of ppb. This sensitivity and accuracy gives
this method its superiority over all other physical and chemical methods of
detection.
Some details of this method are given for the following pollutants: NO, NO2 ,
SO 2, O3, HCl, C2H4, benzene and toluene, as well as atomic mercury. This work
shows, for these pollutants, absorption wavelengths, differential cross sections
and detection limits. In addition to dealing with the technical requirements and
different designs of Lidar.
On the other hand, this review study handles the characteristics of many
laser sources used in lidar systems such as, Nd:YAG- laser, Dye- laser and
others. Especially it concentrates on pulse energy, time duration, repetition rate
and nonlinear crystals, used for frequency doubling, which broaden the
working region of the lidar.
