A simple nondestructive method of measuring the refractive index and thickness of transparent films on reflective substrates has been developed. The technique involves the use of a microscope equipped with a monochromatic filter on the objective and a stage that can be rotated so that the reflected light is observed at various angles. The film thickness, d, is given by d = {[ΔNλ]/[2µ(cos} r2, - cos r1)], where λ is the wavelength of the filtered light, µ is the refractive index, and {ΔN} is the number of fringes observed between the angles of refraction r2, and r1.

1 aPliskin, W A1 aConrad, E E uhttp://portal.acm.org/citation.cfm?id=1662391