[ATM] Schmidt Corrector Thickness

[dlwebb at canit.se (Dominic-Luc Webb)]

On Sun, 22 Feb 2004, Bob May wrote:

> I'm working on a 6" F1.95 corrector and had two failures so far with a
> thickness of 4.3mm due to the glass breaking while under tension.

Where to begin...

I knew something like this was possible for my scopes, also
similar F/ratio, but larger apertures. I am using 6 mm optiwhite.
I think thicker glass will break more easily, although the
curve will be ever so slightly different. I considered these
stresses from the onset and decided to skip tensioning. Two
options are possible. One option is settle for a more simple
curve, like a sphere or hyperbola (test from the back side),
which can also give good performance. The other modification is
to use a grinding polishing wheel using a protocol that follows
the protocol for the curve one is trying to generate (e.g., relative
time at any given distance from center is dictated by the equation
for the curve one is trying to get). See...

www.megspace.com/science/stp/catadioptric/310schmidt/310schmidt.html


Dominic-Luc Webb