Extinction and small angle scattering by thin plate crystals

Abstract

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.

Numerical study of the extinction matrix for a plate crystal

“…(7)). In this case, the squared wave number [5,11] and the diffraction integral that have dimensionalities of areas enter into the formula for the amplitude matrix elements l j S as multipliers.…”

“…In [11] we have already obtained formulas for l j S for arbitrary scattering angles within the framework of the plate crystal model. It should be noted that in the case of scattering in the forward direction (θ = 0˚), S 12 = S 21 for plates, and the elements of the extinction matrix determined as a difference between S 12 and S 21 are equal to zero.…”

“…Its representations also differ [1, 2,9,11]. This depends mainly on the initial description of the scattered field (see Eqs.…”

“…In [11,12], an optical model of a semitransparent plate was described within the framework of the method of physical optics that allows the extinction and scattering matrices to be calculated for any arbitrary observation point. The elements of the extinction matrix represent a linear combination of the amplitude characteristics S ij , and the elements of the scattering matrices are specified by square-law dependences of S ij .…”

“…We note that in calculations of М ij and K ij , it is most difficult to determine the scattered field amplitudes the expressions for which are presented in [11] in the form of the calculation algorithm that can be easily transformed into computer codes. Having substituted expressions for the amplitudes with the proper coefficients into Eq.…”