Variable Neutral Density Filter

This program will develop a cost effective, highly repeatable process for fabricating spatially variable neutral density filters with very tight geometry. Three fabrication methods will be developed and evaluated. The first method consists of sputtering through a moving deposition mask. The mask is sheared relative to the part to achieve a rapid spatial change in optical density. The second method consists of sputtering through a lithographically patterned porous plate. The mask is vibrated at high frequency but low amplitude to produce a uniform distribution. The third method consists of shaping the sputtering target. Demonstration runs will be made in phase 1 to establish the process and verify run-to-run stability. Parts will be characterized using a high speed densitometer. It is anticipated that Phase 2 process development will incorporate aspects of all three methods to produce filters suitable for environmental and application testing.