[ATM] Blank question

["Jeremy Batterson" <jdbaterson@msn.com>]

Okay, so you want to build an F1 or F2 mirror four or five feet in diameter, but you can't spend $25,000 on a mirror blank. So, what's the alternative?

 

1) Get a big chunk of obsidian?

2) Is there some alternative material, a kind of plastic? Maybe buy a big plastic door and cut out a disc?

3) Ceramic? Build a big clay disc, mold it to the desired curve, cover it with an inch of  glaze, fire it in a kiln and then grind, polish, etc.?

4) Make a big disc of china clay, and fire it, then grind it?

5) (If you live on Titan, it is cold enough that you could make mirror out of water ice.)

 

Let us imagine that you are willing to sacrifice perfect image quality (since there will be some impurities on these materials) for the sake of massive light-gathering power, for viewing nebulae, etc, at relatively low powers of magnification. 1, 2, and 3 have been done, on a small scale, and I wouldn't be surprised if 4 has been as well.

 

Jeremy D. Batterson
Ridgefield Park, NJ
(201)441-4888/(877)305-8856
Literary & Astronomy Page:
http://members.lycos.co.uk/jeremybatterson<http://members.lycos.co.uk/jeremybatterson>
_______________________________________________
ATM mailing list http://www.atmlist.net/