Clock wise from the upper left:
12.5 inch 2 inch thick pyrex flat. Back fully polished.
Wedge .001 inch. Flat is flat to 1/16 wave or better
over 11.5 iches diameter. Edge slightly turned down.
Provides an excellent diffraction image when tested
with an long focus 8 inch test sphere at a 70 degree
angle and double pass. A picture of the flat using a
shearing interferometer is displayed below the flat.
Since it is double pass the fringe spacing is 1/4 wave
and since the deviations are less than 1/4 of spacing
this indicates a surface accuracy better than 1/16 wave.
$400 plus shipping ***SOLD
Very nice 16 inch by 1 inch thick blank from D Cassaro.
curve generated to f3.4. Substrate is plate glass but is very well annealed. Includes professionaly made
Couder mask and shipping crate. $200 plus shipping
8 inch f20 sphere. Beral coated. Nice figure. Surface
better than 1/16 wave. $100 ***SOLD
6 inch f8 and 1.1 inch eliptical diagonal. Purchased
from Orion 2 months ago but bubble wrap never opened.
$75 plus shipping ***SOLD