OPTICAL-SURFACE ANALYSIS OF GRADED-INDEX COATINGS ON GLASS

A method fur the determination of the refractive index close to an int er-face. valid far inhomogeneous films, is presented as all extension of the Abeles-Hacskaylo technique used for homogeneous films. Consiste nt refractive index values, with precision in the third decimal place, are determined for Ag+ (1.550 +/- 0.001) and K+ (1.522 +/- 0.002) ion -exchange films on glass, as well as for bare glass substrates (1.509 +/- 0.002), in the neighborhood of their interface with air. The valid ity of the method is discussed in simple fundamental terms, which, alo ng with the experimental evidences, indicates applicability to any gra ded index film, provided an index discontinuity is present ar one of i ts extremes. (C) 1997 Elsevier Science B.V.