STTR Phase I: Advanced Control of Electron-Beam Deposition for High Precision Optical Coatings

Vacuum Process Technology,Inc., Plymouth MA

Investigators

Abstract

This Small Business Technology Transfer Phase I project is focused on developing an advanced control system for improving the manufacturing capability of electron-beam deposited optical coatings. The objective is to develop a system that reduces growth rate variations, resulting in higher yield and production rates, thereby reducing manufacturing costs. The system will also enable more precise manufacturing of coating geometry and structure which are required for more advanced applications. Examination of the current control practices and process characteristics reveals significant opportunities for improved performance. Preliminary experiments with silica have shown that deposition rate variations can be reduced by a factor of 4-10 which is shown to significantly improve the optical coating quality. This Phase I research is directed at answering several unresolved technical challenges as well as obtaining a more formal quantification of the performance characteristics of the proposed control system in order to determine its commercial potential. The specific objectives for Phase I include: a) reduction of concept to a general algorithm that is robust on a run-to-run basis; b) development of a control strategy that eliminates problems associated with long deposition runs; c) performance evaluation for other important but difficult to deposit materials; and d) quantifying critical production performance characteristics to better determine the commercial significance to end users. To insure that the control concepts are commercially viable, the research experiments will be conducted on a production scale system and will be focused on commercially important manufacturing objectives and designs. The commercial application of this project is in optical coatings for many important applications in telecommunications, defense, satellites, and high energy lasers. These advanced applications require improvements in manufacturing capabilities in terms of achieving greater precision over a greater number of coating layers while being produced in large volumes and at high rates. Although electron-beam vacuum deposition has been used to manufacture the majority of these coatings due to its economics and processing capabilities, more stringent coating requirements are needed in advanced applications.