Re: [ATM] 7 inch spherical mirror

[Alexis Cousein <al@sgi.com>]

Dominic-Luc Webb wrote:
> I think entrance pupil may be located at at/near
> the focal length for a Newt,

Not on most practical designs (where even off-axis you use the entire
mirror).

The only ways to design a Newt with an entrance pupil
that far away is to have e.g. a UTA ring/tube diameter equal to
the mirror diameter (or smaller, but that is not a rational
choice on a Newt) or a secondary that *just* fully illuminates the
on-axis object. Those have the pupil located at the UTA ring resp.
the secondary.

Otherwise, the mirror is the entrance pupil for at least the part of
the field that is close to on-axis.

Anyway, it doesn't matter that much on a Newt with a paraboloidal
mirror.


-- 
Alexis Cousein                                  al@sgi.com
Senior Systems Engineer/Solutions Architect     SGI/Silicon Graphics
--
<If I have seen further, it is by standing on reference manuals>

_______________________________________________
ATM mailing list http://www.atmlist.net/