Integrated ion beam milling and coating for precision optical fabrication

An ion beam milling system, used for precision optical fabrication, was modified to easily allow deposition of thin films onto the same optics within a single vacuum operation. A series of coating experiments was performed to assess this approach to integrated ion milling and optical coating. Attempts were made to maximize the deposition rates while maintaining a narrow distribution of coating material to provide the optimum total process time. A series of shaped sputter targets was found to maintain high deposition rates similar to those of a flat target but without having the desired effect of narrowing the material distribution. Apertured shields produced narrow material distributions but at the expense of significantly lowering the deposition rates. Despite these limitations, analysis shows that thin optical films can be produced in a reasonable time by this approach.