Abstract

The use of attenuated total reflection (ATR) to characterize absorbing thin films provides a very sensitive tool, which is masked if the layer under study is overcoating a thick coupling film, e.g., silver on photoresist. Using ray tracing through the multilayer, we study the waveguide and interference conditions, particularly when the photoresist has recorded a holographic grating, which allows more than one beam to be coupled to the system. An additional problem arises when cross talk is produced by the diffracted beam when it is "reflected" back by the same grating onto the main beam and enters the detector. The resulting intensity is modulated by all these factors, and the optical properties of the metal itself are masked. A simple procedure is developed to discriminate the three phenomena involved in the experiment.

© 1990 Optical Society of America