Re: ATM Sticking Together

[Andy Saulietis <iss@pvtnetworks.net>]

Mel writes,


> > Are there any modern adhesives that match particular coefficient of
> > expansions with commonly used glass (plate, pyrex, whatever), that if used
> > with precision ground surfaces to mate, would result in a bond that would
> > not distort the glass and that could survive aluminizing and the vagaries
>of
> > time?

UV cured epoxies for bonding lens elements has been around for
a long time, you can even get versions having differing degrees of
hardness and index of refraction. Once it sets, it's virtually
*impossible* to separate the bonded glass.

Unfortunately, this bond makes a thermal barrier (as would RTV)
so there would be a lot of stress with temp changes if Pyrex
or common glass were used. This is why Zerodur is used to make
large composite optics..it can be welded and its CTE is virtually
zero so no stress due to temp variations across the welds. Not
very practical for us, it costs ~$7/cu in.

It seems to me that a composite mirror might be possible if
the CTE were very low & the optics could be figured & used at a
well equalized temperature.


Andy Saulietis
ISS Enterprises
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Mayhill NM 88339


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