Re: [ATM] Re: Aplantic Gregorian

["matt" <mariusrf@bellsouth.net>]

-----Original Message-----
From: vladimir sacek <vladis.2@juno.com>
To: atm@atmlist.net <atm@atmlist.net>
Date: Sunday, November 28, 2004 4:24 PM
Subject: [ATM] Re: Aplantic Gregorian


>Matt Tudor wrote:
>
>>I have not seen yet any reference to a Gregorian Mersenne arrangement .
>Is
>>there any book, article, publication that treats it in detail ?
>
>I'm not aware of such, but the design is basically simple.
>Any two mirror system where both mirrors are paraboloids
>sharing common nominal focus produces collimated beams,
>free from 3rd order coma, astigmatism and field curvature.
>Secondary mirror acts as aperture stop, through which collimated
>beams diverge toward primary. Axial beam is parallel to optical axis,
>while beams off off-axis points diverge, according to their
>field angle. Original Mersenne uses primary mirror to
>form final image from the bundle of collimated beams
>formed by secondary, but imaging element can also be refracting
>objective or (for larger apertures) a smaller
>all-reflecting or catadioptric system.
>
>Final aberrations in any case are determined by those of the
>imaging element. Size of aberrations will be more or less
>different than those for imaging element used alone, because
>of the entrance pupil displacement.
>
>
>Vlad
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>ATM mailing list http://www.atmlist.net/
>
thanks for the reply. What you said above is about all I was able to learn
from all existing sources. What I'm interested in is a more indepth study,
related to the aberrations it *does* introduce . Final or total aberrations
will be increased due to the imaging element, obviously,  but I'd like to be
able to find out what wavefront aberrations the Mersenne itself contributes
, ideally to be able to quantify them and then decide what imaging elements
to follow in order to insure a reasonable tradeoff for my project.

best regards,
matt tudor

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