[Fwd: Re: ATM 12.5" f/5 Double-Arched Mirror Blank.]

[Roger Ceragioli <rogerc@as.arizona.edu>]

-------- Original Message --------

Subject:	Re: ATM 12.5" f/5 Double-Arched Mirror Blank.
Date:	Sat, 14 Sep 2002 12:51:59 -0700
From:	Roger Ceragioli <rogerc@as.arizona.edu>
To:	Galogaza <elizabeta.galogaza@siol.net>
References:	3D8216AB.8090207@as.arizona.edu"><3D8216AB.8090207@as.arizona.edu> 004f01c25bbb$e55107a0$02000003@siol.net"><004f01c25bbb$e55107a0$02000003@siol.net>

Hi, Vladimir.

The flat annulus is about 2 cm wide.  And yes, the blank rests just on 
that.  The arches are designed to take the load of the glass above them. 
 And so far I have seen no signs at all of any problem during 
grinding/polishing/figuring--or in the telescope itself.  My only 
problem has been the turned edge with I missed until star-testing.

            Mirror Surface
---------------------------------
--.      .-------------.      .--
   \    /               \    /
    \__/                 \__/

The blank looks sort of like above in section, only with curved arches. 
 It rests at all times on the annulus at the bottom of the arches.

Hope this helps,
Roger

Galogaza wrote:

>Roger,
>
>After you generated back of the double arch mirror,
>how do you support the mirror for grinding, polishing and figuring.
>I suppose the mirror is not resting only on the rim
>of 80% annulus, if I visualize your mirror correctly.
>
>Regards
>V
ladimir.
>
>
>