In the framework of the physical optics method, we performed a numerical study of the energy and polarization characteristics of the optical radiation, transmitted through the semitransparent plate crystal. It is found that the dependence of the energy characteristic of the field, scattered in the near-forward direction, on the particle physical parameters is most substantial for the scattering angle not exceeding 4 degrees, and for IR wavelengths. It is shown that for certain combinations of the particle physical parameters, the off-diagonal elements of the extinction matrix and scattering matrix differ from the first elements of the respective matrices within 1 order of magnitude.

The algebraic formula of the backscattering coefficient has been derived within the scope of the physical optics method. The formula relates the lidar return anomalous high amplitude of observed experimentally with the principal parameters of a polydisperse crystalline medium. It is shown that at the lidar small-angular scanning relative to the normal to the ice-plate preferred orientation, the average size of the plate can be defined and the flutter size can be evaluated from the behavior of the lidar return variation.

The absorption spectra of exhaust gases (H₂O, CO, CO₂, NO, NO₂, and SO₂) and aerosol (soot and Al₂O₃) particles were modeled at different temperatures for the first time and suitable spectral ranges were determined for conducting laser remote sensing of the combustion products of jet engines. The calculations were conducted on the basis of experimental concentrations of the substances and the sizes of the aerosol particles. The temperature and geometric parameters of jet engine exhausts were also taken from the literature. The absorption spectra were obtained via the line-by-line method, making use of the spectral line parameters from the authors' own high-temperature databases (for NO₂ and SO₂ gases) and the HITEMP 2010 database, and taking into account atmospheric transmission. Finally, the theoretical absorption spectra of the exhaust gases were plotted at temperatures of 400, 700, and 1000 K, and the impact of aerosol particles on the total exhaust spectra was estimated in spectral ranges suitable for remote sensing applications.

The relationships for the backscattering cross sections are derived within the scope of the physical-optics method for the case in which polarized optical radiation interacts with an oriented semitransparent circular plate. Theoretical investigation of the depolarization relation is carried out for the polarization signal backscattered from a set of oriented circular plates. An algorithm is suggested for the calculation of the orientation angles of the plates in the scattering volume.

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