[ATM] Ritchey-Chrétien

[Bob May]

First off, a Hindle Sphere is just a fancy name for a spheerical
mirror with a hole in the middle.  Its size for a telescope
secondary will be about the same diameter as the primary and half
the ROC of it.  The biggest difficulty in doing such is all fo
the glass tht needs to be removed.  If you've got a full
thickness piece of glass, make the Hindle Dpheree first and then
make the secondary to the right shape.  After that, grind the
primary mirror from the Hindle sphere and finish the scope.
Final testing of the system can easily be done on Polaris with a
Ronchi grating and you can correct any errors left after finding
out which surface is the problem.   The grinding and polishing of
the surfaces is not going to be difficult.  The biggest problem
is actually testing the surfaces to at least a tenth wave and
prefferrrrably better.  Do make suree that you haaa the
mechanical parts built before testing on Polaris or things will
be rickeety and you 'll be frustrated from not getting proper
results.  Always having others to bounce your problems off of
(like us!) will help a lot in doing the work.
Bob May

rmay at nethere.com
http: slash /nav.to slash bobmay
http: slash /bobmay dot astronomy.net