Evaluation and Analysis of Optical and Electrical Constants of Thin Films as Functions of Reflectance and Transmission Data by Electronic Digital Computation*

Abstract

Whirlwind I, an electronic digital computer at M.I.T., has been used to calculate accurately the optical and electrical constants of thin metal films on nonabsorbing backings and of aluminum oxide films, and to check approximate relations which may be conveniently used in the absence of a digital computer. The conductance per square of film is found to be the principal physical property determining the behavior of conducting films toward incident infrared radiation. The variation with wavelength is related to the finite relaxation time of the free electrons and to imperfections in the films acting as condensers. In the visible wavelength region the two sets of optical constants were evaluated for different thicknesses of gold deposits and compared to optical constants previously reported.