Evaluation of gold, silver, and dielectric-coated hollow glass waveguides

Analytic methods involving gravimetric analysis and titration have been developed for the determination of the coating thickness of thin films used in the preparation of IR-transmissive, hollow glass waveguides. These methods not only provide a highly accurate means of determining the film thickness but also, in the case of the dielectric layer, a method for controlling and monitoring the dielectric film during the fabrication process. That is, a correlation made between the Agl thickness and the iodination time using titration methods has led to more uniform coatings. A gold-coated hollow waveguide for applications in harsh environments has also been developed. Gold films are successfully deposited on the inner surface of the glass tubing with good adhesion when a silver layer is deposited between the glass and gold surfaces. The visible and near-IR spectrum measured shows that the surface of the Au film is very smooth. (C) 1996 Society of Photo-Optical Instrumentation Engineers.