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Re: [ATM] 8" F/4.2 progress
Thanks Vladimir, that certainly puts things in perspective.
Julio
-----Original Message-----
From: Vladimir Galogaza [mailto:vladimir.galogaza@zg.htnet.hr]
Sent: Friday, October 28, 2005 10:35 AM
To: Julio Sanchez
Subject: Re: [ATM] 8" F/4.2 progress
Julio,
> all you need is an optical flat at least the
>size of the primary.
Put in this way it may look like this is trivial task
to have or to make a flat that big.
>Also that a quarter wave flat is good enough for
>autocolimation. The flat is actually a flat mirror.........
So the problem of making and testing the telescope
mirror is "reduced" to first making and testing a flat of at
least the same size and at least 1/4 waves good.
In reality making such flat is not easier than making
a mirror and the most popular atm approach is to
make three flats for the sake of testing by ABC method.
Alternative, to buying a flat, is financially equal to buying a finished
telescope mirror.
The autocollimation solution with a flat is OK if flat can be
borrowed for testing purpose, but who will lend such an
expensive tool?
This is the reason why autocollimation flats are much les
abundant with atm-ers than telescope primaries. It seems that
even diagonals are more often purchased than primaries.
Regards
Vladimir.
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