Re: [ATM] Ultra-Thin Edge Support Idea - RE:[atm_free]ULTRA-THIN30"mirror from Hong Kong

["Cord Scholz" <cord@astro-image.com>]

Peter,
the astatic cell is probably the best way to support the mirror but it's
also the most complicated to design and fabricate. What we need is a tool
similar to Plop which allows us to calculate astatic cells.
Here is a nice picture of an astatic cell for a 47" mirror:
http://www.aip.de/groups/activity/gallery/stella2factory/Stella2Spiegelzelle
_011?full=1
I'd build one for the equatorially mounted 24" I'm working on but I have no
clue how to calculate such a beast.

For conical mirrors of moderate size the central support is very promising.
Many Cassegrains and RCs use this method, I don't see any reason why it
shouldn't work for a Newt. 

Cord



-----Original Message-----
From: atm-bounces@atmlist.net [mailto:atm-bounces@atmlist.net] On Behalf Of
Peter
Sent: Saturday, January 28, 2006 3:17 PM
To: atm@atmlist.net
Subject: Re: [ATM] Ultra-Thin Edge Support Idea - RE:
[atm_free]ULTRA-THIN30"mirror from Hong Kong

Hi,

Lots of good discussion here! Thanks for that.

We have a great number of really smart and experienced people on this list
so let's break the paradigm that thick mirrors are they only way to go and
come up with a way to adequately support ultra thin mirrors? Observatory
mirrors have thickness ratios which are radical in comparison to the 30:1
just discussed. Surely with all of the potential on this board we can come
up with a means to support large thin mirrors to an accuracy of 1/4
wavefront.

- should be abandon lateral edge support and go with silicone attachment of
the mirror to the cell?
- should we centrally support the mirror from the rear just like conicals by
gluing a rear support?
- should we use astatic cells?
- for super thin mirrors maybe we could built defection controls into the
mirror support to improve image quality?

I think it would be really cool if we as a group could identify the best
approaches, perform experimental design on these ideas and examine the
factors affecting success.

The outcome of this work could set a new standard for amateur telescope
making. This could be ground breaking work!


Peter

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

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