Re: [ATM] History of moving mirrors for Schmidt Cassegrains.

[Andy Saulietis <iss@pvtnetworks.net>]

Ken Lowther writes:

>I saw a an old Celestron that had 3 lead screws that moved so that the primary
>didn't 'flop' around.

We had a Celestron 16" in my lab at NASA that used the 3 leadscrew
primary focusing method..however, this one did have a lot of
axial wobble while focusing. We replaced the primary cell with
a fixed mount and built a secondary focusing ram tha incorporated
linear precision bearings and a motor driven leadscrew to
fix the wobble..this made a dramatic improvement it the accuracy
of positioning the telescope, which at the time was used to optically
track the Apollo spaceraft during trans-lunar coat. We used
an integrating image orthicon video camera to record the images
to near lunar distance.

However, the 37" I'm currently designing will move the
entire secondary cage with leadscrews constrained by
precision linear bearings..the cage will also rotate
for field derotation.




Andy Saulietis
ISS Enterprises
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Mayhill NM 88339


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