To: Mark Suchting 
From: ray{at}stabilite.com (Ray Desmarais)
Cc: atm{at}shore.net
Reply-To: ray{at}stabilite.com (Ray Desmarais)


 Ray wrote:

> > I have successfully made a 36" flat .9" thick, and a
72" mirror .9 "
>Thick.

For the purposes of the discussion , lets get some perspective here . These
big spherical mirror surfaces are basically reverse `Flux' collectors , not
precision optical surfaces.

~Mark

Hi All,

In reply to Mark

I don't remember you being at the shop during manufacturing or testing of
these surfaces. If you had been you would have discovered that the mirrors
were made as an experiment to see what the limits were. The end users
specifications were exceeded by a factor of at least 10 times. This was an
Ideal situation to see what is possible. This is one of the largest
thinnest mirror ever made.
The weak point in the system is in the cell to hold the mirror. The
27-point cell holds the mirror to a few waves, which exceeds the specs by a
factor of 6 times.
This was not my first dance; the intention of my post was to try to assist
anyone who wants to proceed with a large thin mirror, and to pass on any
info to reduce the learning curve for them. I am certain that the large
mirror could have been corrected to better than 1/2 wave {at} 633 nm with
little effort. The problem is in supporting it in the scope at various
angles.
I have some of the best testing equipment in the industry, which makes it
easy to scientifically evaluate what is going on. It is difficult to post
on this list for me, I have an enormous amount of information to pass on
and feel reluctant to do so.  I'm not saying that everyone should try and
make a 72" diameter mirror that is .9" thick for a telescope.
I wanted to make my self available to pass on information to help people
who are seriously considering making a large thin mirror, and to help them
avoid the black holes that are out there.  I do not have a lot of time to
read or post on the list. However I would like to help others who want to
push the limits of optical fabrication.

RAY
Ray Desmarais
479-890-4918
ray{at}stabilite.com

Education is not something that can be completed. It's a way of life.

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