Re: [ATM] Mirror cell for an 8" mirror

["Olivier Biot" <olivier.biot@gmail.com>]

Hi,

I keyed your mirror specs in PLOP, assuming plate glass and no central
obstruction. A 3 points cell yields a RMS error of 3.08095e-06mm
(3.08nm) which is *much* better than lambda/100. The P/V error is
14.12nm. You have to place the 3 support points on a circle at
41.4759% from the center.

If you place the 3 support points at 60% then PLOP tells me your
mirror cell will produce a RMS error of 5.75979e-06mm (5.76nm or
~lambda/100), and a P/V error of 24.5nm.

I am inclined to go for the PLOP values (41.5% instead of 60%).

Cheers!

Olivier

On 11/2/07, Corona Australis <corona_australis@westnet.com.au> wrote:
> I'm making a 3 point mirror cell for an 8" mirror. I was wondering and
> also hoping someone here could tell me what would be the preferable
> distance from the mirrors centre to position the three points.
>
> The mirror is an F/6, 204mm neat in diameter and is of a thickness of of
> 23mm.
>
> I was going to go with 60% from the centre seperated 120 degree. Does that
> sound alright?
>
> Thank in advance
>
> Regards,
>
> Ozzy
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