A Thin Film Polymer Figuring Process for Composite Mirror Correction

The objective of this SBIR is to demonstrate feasibility of correcting figure errors on composite mirror substrates by systematic deposition of a thin film polymer. This process is analogous to ion figuring but in reverse. In the proposed process, a polymeric film is added to the mirror surface where needed to correct figure errors. The film is created by flash evaporating an acrylic monomer through a nozzle and e-beam (or UV) polymerizing the monomer in-situ. The evaporation process occurs under vacuum conditions. Since the evaporation rates are typically orders of magnitude faster than ion figuring removal rates, with proper flow control, a significant cost and time savings could be realized. Since the monomer is cured by electron beam or UV light, the process can occur at room temperature, whereas ion figuring heats the mirror surface adversely affecting some mirror constructions.Successful execution of this project could provide enabling technology for mirror programs such as FIRST, where ion figuring rates might be too slow to be practical and where thick sacrificial resin coatings (necessary for ion figuring composite mirrors) could adversely effect cryogenic performance. This technology could offer advancements for mirror programs such as FIRST, NGST and LIDAR mirrors.