10-inch telescope mirror blank, Corning fused silica For Sale
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10-inch telescope mirror blank, Corning fused silica:
$129.49
10.225-inch diameter Corning fused silica mirror blank
For your consideration is this vintage (1970\'s) optical glass blank made of fused silica, Corning code 7940. According to the product brochure, \"...this is a high purity synthetic amorphous silicon dioxide manufactured by flame hydrolysis. This noncrystalline, colorless silica glass combines very low thermal expansion coefficient with excellent optical qualities\". The CTE value is stated as 0.52 x 10-6 per C. This is better than borosilicate, such as Corning Pyrex (3.3 x 10-6 per C), and certainly superior to plate glass.
This blank is NOT molded, but cut and machined from a parent boule. Both faces and the outside diameter are machine-ground to a medium-grit finish; the faces are nominally flat, and the perimeter is square-cut (not tapered).Both edges have modest chamfers, with a few minor flake-outs, but otherwise no damage, cracks or cavities. The perimeter has numerous ink-markings; see photos.
Wetting the surface and edge-lighting allows one to see inside; see final photo. There are some tiny bubbles (10 by my count) scattered about; the largest is just under 1 mm; all others are 0.5 mm or smaller.
Outside diameter: 10.225\"Thickness: 0.762\"Weight: 4 lbs, 15.7 ounces.
This item will be well packaged for safe delivery. Estimated shipping wight is 8-9 lbs. Local pick-up is an option.
Thanks for looking.
