Properties of a leaky quasi-waveguide formed by a thin film of refractive index smaller than the substrate are described. By exciting these leaky waves through the substrate, we have demonstrated a convenient and accurate method of measuring both the refractive index and thickness of thin films. Experimental results are given for polystyrene, with a demonstrated accuracy comparable with both that of prism coupling into a waveguiding film and with ellipsometry.
© 1983 Optical Society of America
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