Fresnel diffraction patterns produced by slits in semitransparent metal and dielectric films show a fringed structure which depends upon the index of refraction and the thickness of the film. Intensity distributions calculated on the basis of scalar diffraction theory compare well with the experimental results.
JOEL A. GWINN, JOHN F. KIELKOPF, and PAUL M. GRIFFIN, "Fresnel Diffraction of Light by Slits in Semitransparent Films," J. Opt. Soc. Am. 56, 1338-1341 (1966)