Re: [ATM] Moulded Mirror comment by ANY telescope maker

[Tony Gondola <acgna@comcast.net>]

Not so fast Russell. Small diameter optics are currently being molded to 
sub micrometer accuracy. The best figures I've been able to find with 
just a little searching have been quoted with an accuracy of around 5 
waves. Not telescope quality but you can bet it's getting better all the 
time. Nikon and other companies are pushing this technology very hard 
because it really opens the door on some wonderful things. Not only does 
it make optical production very uniform but it also means that one shape 
is as easy to make as another. That really opens the barn door because 
you no longer have to optimize your designs to be relatively easy to make. 

One of the neatest tricks I ran across while researching this was a 
company that was computer designing molds that corrected for the change 
in shape as the material cools. By calculating the expected deformation 
you can make a mold just the right shape so that the element distorts 
into the wanted shape as it cools rather then the other way around. The 
ability to machine and handle materials at nano scale is of very high 
interest right now. I wouldn't discount this technology, it's on it's way.

Tony


Russell Jocoy wrote:

>    To all,    The "moulded mirror" comment in any advertisment or listing 
>from any telescope maker is just mumbo jumbo saying that this glass disk was 
>not pregenerated from a machine.. This glass disk was moulded with the 
>determined "f" curve onto the blank. Of course we all know how accurate this 
>curve needs to be..., well beyond any mould known to man.  I don"t care if 
>you mould it, generate it, sit on it, you will still have to grind it, 
>polish it, and figure the surface. It is totally ridiculous to think that 
>any mould could come close to a surface that could reflect a wave length of 
>light close to what is needed to focus to your eye with any definition..    
>Russ Jocoy
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