To: atm{at}shore.net
From: Jim Burrows 
Reply-To: Jim Burrows 


At 10:18 2003-06-02 -0700, Scott Berfield wrote:

>I need (I think) to make a couple of smaller laps as I parabolize my 12"
>- one around 6" and around 3". For small laps is it necessary that the
>substrate match the mirror curve or can I simply pour a lap on a flat
>disc the right size, press it and get going?

What's the f/ number of the mirror?  If it's not too fast, try some of
Texereau's other methods of parabolization on p. 97.  Small tools are
probably the slowest and hardest of the parabolization methods.  Whether or
not the substrate has to approximate the mirror surface would also depend
on that f/, as well as the size of the tool, i.e., the 6" is more
likely to end up with too much thickness difference between edge and center
than the 3".

         -- Jim Burrows
         -- mailto://burrjaw{at}earthlink.net
         -- http://home.earthlink.net/~burrjaw
         -- Seattle N47.4723 W122.3662 (WGS84)

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