Re: Alternative mirror technologies, WAS ATM Liquid-mirror telescopes

[Ken Harrison <kmh@ozemail.com.au>]

Chuck Knight wrote:
> 
> > I could probably build a mylar
> > mirror for even less!  (Say, have you actually tried that vacuum
> > technique, or is it just theory?  I have a 14" embroidery hoop
> > that's just "screaming" for an experiment!  Why would it form a
> > parabola, specifically, instead of a spherical mirror?)
> 
> I've got a question.  I've seen occasional references to mylar
> film mirrors...pulled into a parabola with a vacuum.  What
> makes it take on a parabolic shape?
> 
> I understand how a spinning liquid is forced into a parabola,
> but how does the membrane mirror work?
> 
> If nothing else, it sounds like a fun experiment!  Now where
> did I put those mylar balloons?  :-)
> 
>      -- Chuck Knight
Not new. I have all the details of a vacuum mylar mirror set up that was
actually built and tested at Strathclyde University at Glasgow. OK for
photography by the mylar surface accuracy was NBG for visual. S&T had an
article on vacuum forming a thin plate glass mirror to I think f9. I
have access to ALL the S&T back to 1940 If I get the chance I'll check
the references for you.
Ken H