40-inch Mirror Fabrication Update
At the 11/14/09 VMOA board meeting Mark Hillestad reported that Steve Follett and he had progressed figuring the 40-inch primary mirror over the last two months from 12 wavelengths of light deviation from parabola to 6 waves. Once the basic figure is achieved, then there will be iterations of test-and-figure to perfect all of the zones across the mirror surface – a fussy but necessary process to minimize the image size of a point source. He still expects that the mirror figuring for the 40-inch primary will be complete around March 2009.
Mark also reported that work has begun on the 8.465-in diameter secondary mirror, starting from a blank. The first steps that are necessary are to flatten the back of the blank and that’s that work is expected to continue through December. In January Steve and Mark will be ready to begin the front surface grinding procedure.