Re: [ATM] Flexed mirrors

["Bill Kelley" <flex@commspeed.net>]

Subject: Re: [ATM] Flexed mirrors


> On Sun, 13 Jan 2008, Bill Kelley wrote:
>
>> The flex concept becomes very useful with the trend toward large, fast
>> mirrors. On these conventional parabolizing by polishing to a smooth,
>> zone-free figure is a bear of a problem for many atm workers.
>
> When I confronted Alan Adler some years back about flexing a
> fast mirror, it seemed clear we had differences in what we
> perceived as fast. I perceive fast as F/1.0 to F/3.0. Alan did
> not seem very optimistic at that time for these mirrors that
> any of us would call fast. I was not too optimistic myself,
> although, now that I have worked thinner slumped plate glass,
> like 19mm thick and 300 mm diameter, maybe flex becomes an
> option.
>
> I know slumped glass flexes quite a bit on its own, which
> makes testing a headache. But maybe flex can come to the
> rescue if it can correct deformaties from sagging, etc. Of
> course, those of us going for such mirrors are usually not
> wanting a parabolic surface, but who knows, maybe someone has
> some very fast folded visual system where this could help.
>
> Dominic

Dominic et al.,

Thanks Dominic. It's good to hear a thoroughly skilled ATM weigh in on this 
subject. F1 on any size mirror does not seem to be doable by any flex 
scheme. A 10" F2 with an appropriate convex back in at least one thickness 
will flex to a 1/10th wave paraboloid. I haven't tried  more tweaking of the 
thickness and back radius to see if this can be improved.
It probably can at least a little bit.

My point in my first post was to persuade beginners, and others that just 
want to make a fine telescope as easily as possible, that flex has shown 
that it will do it for them.

Regards to all of my friends,

Bill Kelley

_______________________________________________
ATM mailing list http://www.atmlist.net/