Quote:
Originally Posted by Satchmo
Allan - fused glass blanks have been around for 50 years , it just now that the chinese are making then out of plate glass and offering to amateur astronomers. What I have learn from 40 years around optics is that most that you read is self serving spin - lets see how NASA's foray into dirt cheap plate glass 40" mirrors pans out in time . Even with the buttons in between that is a relaively thin blank - the chances of it being 'diffraction limited' at that thickness and from a fused blank are zero I am afraid but that is aside . I was just passing on some actual experience in the field.
Do let everyone know how your mirrors compare - it certainly might not make any difference in the prime focus imaging world - I am an old school visual guy.
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We'll see for ourselves.
They say Strehl ratio of >= 0.975 & also Pyrex not plate glass.
I am willing to take the risk to try & push the envelope.
The giant lumps of glass in peoples mirrors now just couldn't possibly reach
thermal equilibrium as fast as the temperature drops.
Just look at the trouble Anthony Wesley goes to to get the temperatures the same:
http://www.acquerra.com.au/astro/cooling/ballarat/
cheers
Allan