Long Focal Length Large Mirror Fabrication System

NASA is interested in large, coherent, primary mirrors with good optical figure. An approach now followed by all major observatories is to make the large mirror of smaller segments that are phased together. Hexagons 1 meter in diameter are a possible segment size. Over one hundred one meter segments are required even for a 10 meter diameter primary. Segments will have a long focal length, f/20 or more, even if the resultant large mirror is f/2 or less. Means for making and measuring high quality, low scatter, long focal length, large adaptive optic deformable mirrors economically is thus greatly needed, as stated in the subtopic. This proposal presents one solution. Effects of turbulence and air layering are largely eliminated by making most of the long focal length path virtual. A technique for economically superpolishing large mirrors for low scatter is presented and will be domonstrated. A precision fiber optic interferometer said to increase the measuring precision of commercial interferometers by an order of magnitude will be evaluated in Phase I. Its use on large, long focal length superpolished mirrors measured using virtual path length techiques will be demonstrated in the Phase II program.