Re: [ATM] Refiguring cass mirror to newt

["Gord Tulloch" <gord.tulloch@gmail.com>]

Easy enough  - thanks guys!

On 7/29/07, Thomas Janstrom <thomas@moiler.com> wrote:
>
> I've had to do this twice now; I make a pitch lap and carve out the centre
> section to match (slightly over size) the perforation. This way you can
> press as you normally would and work with the same strokes etc. you will
> still get a slight turned edge around the perforation, but as this is
> usually baffled by the secondary mirror it won't have any real effect on
> the
> system's optical performance.
>
> Thomas.
>
> -----Original Message-----
> From: atm-bounces@atmlist.net [mailto:atm-bounces@atmlist.net] On Behalf
> Of
> Gord Tulloch
> Sent: Monday, 30 July 2007 7:45 AM
> To: atm@atmlist.net
> Subject: [ATM] Refiguring cass mirror to newt
>
> Hey all:
>
> A friend has an (apparently) spherical 12" pyrex mirror, likely part of a
> unfinished SCT. He wants to get it refigured to a paraboloid to use as a
> newt - f4.8 so not too bad (haven't tested it yet) but usually I
> understand
> when people polish and figure perforated mirrors they keep the core and
> stick it in the hole with pitch. Any guidance on what I might do with this
> mirror where we don't have a core? Don't worry about it, or fill it with
> something else (dental stone?) so it doesn't mess up the lap? Thoughts
> would
> be appreciated, thanks!
>
> Regards,
>   Gord
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