     This program demonstrates calculation of reflection and
transmission of multilayer systems with isotropic layers.
     Ideology: for the given angle of incedence, we determine kx (the
component of the wave vector of the incedent wave parallel to the plane of the
layer). Suppose that in the last medium we have only 
transmitted wave; kx is the same for all waves in the system; 
without loss of generality, By or Ey (the component of the corresponding
fiels perpendicular to the plane of incedence; the polarization determines,
By or Ey we should use) in this wave near the interface between (n-1)-th 
and n-th media can be chosem equal to unity. From the 
boundary conditions for fields, we reconstruct the fields near this interface
in the (n-1)-th medium. Then we decompose the field in two waves (incedent 
and reflected) and determine their combination near the interface 
between (n-2)-th and (n-1)-th media, and so on, until we determine
the amplitudes of the incedent and reflected waves in the first medium.
From these amplitudes, we determine reflectance and transmittance.
     In the presented program, we calculate the reflectance and
transmittance spectra of a thin film of organic substance. As a substance,
we used CHCl3 (of course, CHCl3 is not suitable for making films, but
it has small number of bands, and its spectrum is presented in reference
books). One can see how the interference pattern "interacts" with the absorption
bands. An interesting feature is that the sum of the calculated coefficients
of reflection and transmission is in fact free of any signs of interference.
     This program was succesfully used for the study of reflection in the Otto
geometry for the system Ge-air-ZnO-SiO2 and gave satisfactory results.
