Warping A Spherical Mirror Into A Paraboloid
While constructing the Ronchi tester that I mentioned a couple of days ago, I took out a 6" f/5 primary mirror that I scavenged from a telescope that I got from a garage sale. It is actually a very nice sphere, as can be seen by the straight lines and lack of any zones or appearance of a turned edge.
But as smooth as it is, a 6" f/5 sphere is only has a wavefront accuracy of more than a wave. It won't perform that well. So what's a guy to do with this nice aluminized mirror?
The (semi) obvious thing would be to strip it and refigure it. I still might do that, but I then started thinking about it and thought about this article written by Alan Adler for Sky and Telescope.
I think I may have to give this a try. I think I should have most of the materials to give it a whirl, and if the mirror looks good on the tester, I may be able to transplant it back into the tube that it originally came in, perhaps with a new (3D printed?) cell.
Stay tuned for more developments.