Newton's Rings?Posted By John Biretta |
I'm fairly certain the pattern is due to stuff deposited on the front surface. It reminds me of the Edmund Scientific "Astroscan" scopes. These were 4.25" F/4.2 and the mirrors were (according to rumor) parabolized in the coating chamber by depositing stuff of varying thickness. Perhaps thats what you have here, sans the Aluminum top coat.
http://www.scientificsonline.com/astroscan-plus-telescope.html
http://www.scientificsonline.com/astroscan-plus-telescope.html