Re: [ATM] Mirror cell design

["Bob May" <bobmay@nethere.com>]

The optimum design for any cell is to support the mirror without placing any
stress on it.  This is why the sling works so well for the Dob type
telescopes as the mirror is basically supported evenly over 1/3 or more of
the edge.  The problem with equatorial telescope is that there is no "up" to
the mirror cell as it rotates about the polar axis.  As a result, there
needs to be several support points so that the mirror may be supported with
any part of it as the present "up" direction and that means 360 degree
support.  It is thus left to devices which can be places anywhere and be
able to provide a support without movement or need for adjustment to the
last wavelength to maintain an even support.  The astatic supports are
really the only way to do this and sevral of them can be used about the edge
of the mirror.  The 3 point method used of yore won't really cut it for the
finest control of the thin mirror as there will be only 1 or two points
actually supporting the mirror and this will cause deformation in thin
mirrors.
Bob May
http://nav.to/bobmay
bobmay@nethere.com
NEW! http://bobmay.astronomy.net


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