Re: [ATM] Too Small Optics-( and flex produced optics)

["David Harbour" <scarab2@cox.net>]

One thing or another can happen: either the optician turns out a SPHERICAL
surface full of rings, or he can turn out an ASPHERIC surface with no rings,
valleyes, or zones whatsoever in it.

I HAVE SEEN BOTH!

And both of them were from the best opticians one would want to do business
with; odd thing is, the one full of rings (a 6" refractor objective, gave
stunning performance); so did Brent Bennet's ("Telescopics") 12.5" mirror
that I tested, that showed NOT EVEN THE FAINTEST ZONE OR RING. I forgot to
mention that it was figured by the man who figured the 101" mirror of the
Ritchey Chretian DuPont telescope in Chile.

Dave

P.S.- Remember, refractor objectives are four times more forgiving than
mirrors for slope errors.  "Ringed up like a pole-tailed cat". "Go figure".

The idea that a spherical surface is less prone to polish out without rings,
is, I believe, a myth.


----- Original Message ----- 
From: "Don Clement" <clement.focuser@verizon.net>
To: "'ATM List'" <atm@atmlist.net>
Sent: Thursday, June 16, 2005 6:14 PM
Subject: Re: [ATM] Too Small Optics-( and flex produced optics)


>
> Jerry wrote:
>
> > I don't buy into the super smooth argument for bending and figuring.
>
>
>
> Then don't! However, there are a few that have maksutovs that can testify
to
> the super smoothness that can be realized with spherical surfaces. I have
> several maksutovs made by the late Max Bray that are very smooth indeed.
>
>
>
> If you are limited by the traditional mechanical means of applying the
> deforming forces then you might be correct. There are many ways to apply
> local forces to deform glass. I can think of a couple-for example, piezo
> actuators or local heating using ultrasonic sound generation. If one
starts
> out believing something cannot be done, then it probably won't. Just
because
> one shows one can't get from here to there by a particular path doesn't
mean
> there isn't some other path that will lead from here to there.
>
>
>
> Don Clement
>
> Running Springs, California
>
>
>
> A very local 5.3 magnitude foot massage today
>
>
>
>
> _______________________________________________
> ATM mailing list http://www.atmlist.net/
>


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