Versatile computer program for absorbing optical thin film systems.

The program for the synthesis of nonabsorbing thin film systems by the method of gradual evolution [J. A. Dobrowolski, Appl. Opt. 4, 937 (1965)] has been extended to include new features and to handle absorbing materials. In the analysis mode the new program calculates the spectral transmittance, reflectance, and absorptance of any absorbing multilayer system for any angle of incidence or plane of polarization. The CIE chromaticity coordinates of the coating can also be calculated. Information on the stability of the system is obtained from an automatically repeated analysis with randomly perturbed values of the construction parameters. As in the original program the synthesis mode does not presuppose a starting design; a layer system consisting of real absorbing or nonabsorbing coating materials may be gradually evolved. The evolution and refinement are governed by the value of a merit function defined specially for each problem. In the new program it is possible to control the sensitivity of the system performance to changes in the construction parameters. The monitoring information mode yields data useful for the construction of a multilayer. The construction parameter determination mode deduces the actual parameters from the measured performance of the system. The operation of the program is illustrated by examples.