Algebraic method for extracting thin-film optical parameters from spectrophotometer measurements.

A new analysis method has been developed for determining optical constants and thickness of a thin film given measured reflectance and transmission values. In contrast to other methods, the present inversion technique is essentially algebraic, not numerical. There is no requirement for an initial guess solution, and there are no missing solutions. The generic measurement configuration is a multilayer structure with no restriction placed on the number of films. However, the film with unknown optical parameters must be the last layer adjacent to the output medium. The analysis method is reviewed and examples presented for both single-film and multilayer structures.