In the present work we offer two novel computational methods, defined as (T,R_f,R_m) and (T,R_b,R_m), for the simultaneous determination of the optical constants, n and k, and the thickness, d, of a thin film from three experimental photometric quantities. The basic experimental configuration is a thin film deposited onto a nonabsorbing substrate, half covered with an opaque metal film. An algebraic inversion technique is developed involving a numerical interpolation procedure in the last step. The methods give all mathematical solutions, and according to the specific case, the physical solution can be isolated by the combination of the two methods or by some estimates of the thin film thickness. When the photometric measurements are available in a spectral range, the (n,k,d) solutions, for which the thickness is one and the same, can be easily isolated as correct. The (T,R_f,R_m) and (T,R-b),R_m) methods can be applied without restrictions to a wide range of n and k values. A numerical example illustrates the applicability and the good overall accuracy of the methods.

Date Published: 4 November 1994
PDF: 10 pages
Proc. SPIE 2253, Optical Interference Coatings, (4 November 1994); doi: 10.1117/12.192051

Published in SPIE Proceedings Vol. 2253:
Optical Interference Coatings
Florin Abeles, Editor(s)