UV OZONE CLEANING OF A REPLICA GRATING

UV/ozone cleaning was evaluated for cleaning a carbon-contaminated rep lica grating. Replica optics represent a challenging test of any clean ing process because of the potential for damage to the epoxy layer whi ch can severely degrade the surface figure and finish. A badly contami nated replica grating was divided into three sections for this study. One section was cleaned using a mercury lamp, another section was clea ned using a deuterium lamp, and the third section was left as a contro l. The results were evaluated using a Ronchi test to determine figure error, a Fotonic sensor to estimate reflectivity, and a microscopic ev aluation using a Nomarski objective to look for surface damage. Surfac e roughness measurements were also performed with a Micromap surface p rofiler. The results indicated that the surface figure and finish were not significantly degraded, and the surface figure was actually impro ved compared to the contaminated condition. The visible light reflecti vity was fully restored in the areas that were cleaned.