Re: [ATM] Ball bearing for triangles

["A. Suijkerbuijk" <a.suykerbuyk@wxs.nl>]

Hi Rafaël,

This certainly is a difficult mirror: thin and very short focus. It could
even influence your eyepieces. Furthermore the star test is very critical, a
slight spherical aberration is easy to see......I am interested to hear more
about your experiments.

Best regards,
Adrie Suijkerbuijk.

----- Original Message ----- 
From: "Raphaël GUINAMARD" <rguinamard@infonie.fr>
To: <atm@atmlist.net>
Sent: Sunday, September 05, 2004 8:00 PM
Subject: Re: [ATM] Ball bearing for triangles


>
>
> > Perhaps the mirror will reach the air temperature very fast, after which
> the
> > aluminum side radiates most. In this case the mirror will cool below the
> air
> > temperature?
> it's exactly what I think
>
> >Or perhaps the meniscus plays a certain role.
> In my case it is not a meniscus. It is a "classical" miror, but quite thin
> (40 mm) and with low focal ratio f/3.3=> 28-29 mm in the center. It's the
> thin thickness in the center and the big difference between thickness in
the
> center and at the edge that could cause the spherical aberation
deformation.
> In a thiker miror or bigger f/d it would certainly not occur.
> But remember that at the moment it is only a theory for my mirror. I have
do
> do some tests before being sure I have this problem
> > About you mirror: You wrote that you see some spherical aberration in
the
> > star test. is it overcorrection or undercorrection?
> If I remember correctly, it is overcorrected
>
> >I suppose this is after
> > cooling?
> yes...
>
>
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