Re: Alternative mirror technologies, WAS ATM Liquid-mirrortelescopes

[rsinnott@skypub.com]

On Thu, 26 Jun 1997, Ken Harrison <kmh@ozemail.com.au> wrote:
>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
>

In our May 1979 issue, pages 491-492, Guillermo J. Cock described his 10.2-inch 
reflector made from a sheet of window glass with a partial vacuum behind it.  
Among other things, he found that the glass had to be thinner than 1/60 its 
diameter in order to be sucked to f/10 without breaking. 

In the same issue, pages 489-490, Maurice Gavin told of his 21-inch f/1.9 
reflector made from aluminized mylar stretched over a cell made from a bicycle 
wheel rim.  A vacuum cleaner provided suction.  He called this instrument a flux 
collector rather than a telescope, because a point source formed an image blur 
about 5 mm across at the focus.  But this approach could have interesting 
photometric applications.

(By the way, Maurice is currently president of the British Astronomical 
Association, I think.)

-- Roger at S&T