Abstract

The ion beam interference coatings¹ (IBICs) made with a Kaufman gun² have produced ultralow optical loss (R > 99.995%) mirrors due to its unique ability to reduce scattering and absorption to very low ppm levels. A main obstacle in the development is the trade-off in the coating speed with the stoichiometry of the coating deposition. Improvement can be sought in two directions: (a) The ion beam current and the accelerator voltage play central roles for the coating speed and the throughput, but the development time is longer and depends on the demand of the coating market, (b) Fine control of the gradient of oxygen partial pressure from the deposition to the target can substantially improve the coating speed without sacrificing stoichiometry. This development is relatively short. It is believed that the speed and throughput of IBICs are comparable with that of the e-beam in the 1990s, while the superior coating quality prevails.

© 1988 Optical Society of America