Re: [ATM] sticking it

["Vladimir Galogaza" <vladimir.galogaza@zg.htnet.hr>]

At first mirrors in spectrophotometers were made by grinding and polishing.
How they did it I do not know because some mirrors were toroids and
very fast compared to the ATM standards.
Since there was need for thousands of such mirrors, production method
has satisfied industrial requirements. I also do not know to what
quality they have been made. But I am now using one of those mirrors
as test mirror in Bath interferometer and I hope to be able to report soon
on this issue.
Then they found out that mirrors thus made are too expensive and
they were ground only roughly, coated with epoxy and proper curve was stumped in
with negative master and let epoxy cure. Than epoxy was aluminized by vacuum
evaporation method and protected with silicium oxide or magnesium fluoride  . So
it seems that vacuum deposition is feasible and outgasing was
not getting in way. Thus made mirrors were cheaper but were not accepted for Al
recoating while previous mirrors were. A rare example where recycling was
used than abandoned, usually it is vice versa.

Vladimir.



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