ATF utilizes multiple process controls to enable the accurate and repeatable deposition of extremely complex optical thin film coatings while minimizing risk. This starts with in-house design software that allows for optimization of multi-layer optical thickness to meet the most challenging spectral requirements. Coatings with hundreds of layers are optimized using thousands of numerical targets for merit functions.
Once designed, customized software allows for error analysis and predicted outcome during the plasma deposition process. This is critical since not all designs have an equivalent probability of success. Coating run results and design vs. performance data are reviewed regularly by both Sales and Manufacturing.
Accurate in-situ measurement of the true optical thickness of the coating is essential. ATF utilizes a custom Optical Monitoring System (OMS) that allows for optical layer thickness control to the picometer level. In essence, the coating is measured as it is being deposited, angstrom by angstrom. The results are fed back into the deposition control for real-time correction and improvement, resulting in very high success rates, even for new coating designs.