ABSTRACT
238In Chapter 5, Section 5.1 presents a brief historic insight into the development of femtosecond lidar technology and femtosecond lasers, as well as perspectives of application of white-light lidars and fiber optic devices. In addition, it describes the main mechanisms of generation of supercontinuum radiation in optic fiber and in atmospheric air.
Section 5.2 considers the lidar equation in the problems of atmospheric sensing by ultrashort (femtosecond) pulses with allowance made for the formation of conical emission and the use of supercontinuum radiation as a main effect for the study of gas–aerosol composition of the atmosphere.
In Section 5.3, we provide the basic equations and describe the Monte Carlo simulation of transport of conical broadband emission radiation in the atmosphere. The main purpose of this section is the demonstration of the approach used by the authors for the solution of direct problems in order to assess the possibilities of the methods for solution of inverse problems. Section 5.3 encompasses some of our numerical and field experiments aimed at the evaluation of the possibilities of applying white-light lidars to the determination of the gas–aerosol composition of the atmosphere, as well as the developed approaches to the solution of inverse problems, in particular, those based on machine learning and artificial intelligence methods.
Section 5.4.1 analyzes the possibilities of water vapor sensing with the application of lidars based on femtosecond sources of radiation. Section 5.4.2 considers white-light lidars for aerosol sensing and presents an iterative method for the solution of lidar equation to determine the optical interaction coefficients, as well as the solution of the problem for the determination of microphysical characteristics of clouds based on methods of neural networks and genetic algorithms. The conducted lidar experiment on the study of microphysical characteristics of artificial aerosol at short paths is described for the first time, and possibilities of reconstructing the microphysical characteristics of thin mists with the use of white-light lidars are evaluated.
