Re: ATM Re: Back Support for Large Thin Mirrors

[Alan Salmon <asalmon@mat.army.defence.gov.au>]

> 
> On the same subject, I wonder if  a series of 27 adustable pads with threaded
> shafts to push on the mirror would be helpful as an INITIAL support
> alignment. I.E. You put a TV camera at the eyepiece and monitor a bright star
> at 45 degrees off the horizon (an average horz to zenith) as you turn these
> adjustments for the best convergence.  Perhaps this "fixed constant" bias
> idea could be used as the actual points with your air/gravity system??? But
> maybe it wouldn't work using the triangular support technique?

Why not attach each of the 27 screws (adjustable pads) to a 
solenoid/stepper motor and record the position for each of the pads at 
each angle from vertical to horizontal having "adjusted for best 
convergence" at each step.

Feed this info into your drive program and have it automatically adjust 
the mirror as it tracks. Obviously some sort of manual override would be 
nice for those times you don't want your mirror wallowing like a pig in 
mud :-)