Archived posting to the Leica Users Group, 1998/10/01

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Subject: Re: [Leica] CorningWare optics
From: George Berger <gberger@his.com>
Date: Fri, 2 Oct 1998 00:49:16 -0400

Hi Jim-

>Who made the glass for the Hubble Space Paper Weight?  jh

I don't know, but I dimly remember that they made the glass for the 100"
mirror in the Palomar Observatory, years ago, when I was still a youngster.


BTW: It wasn't Corning's fault that the Hubble Telescope mirror was not
ground correctly. All they did was to furnish the glass.  Further, I would
suspect that the optical quality of the glass in the Hubble wouldn't be the
same as that used in camera lenses.  The glass is made with rigidity and
with minimal distortion from thermal variations foremost in the
calculations.

After a large telescope  mirror has cooled, it is ground to specifications.
Then, it is silvered, coated and recoated - - as it is a *reflective*
surface - - not a "pass through" lens. The grinding, silvering and coating
processes give a large-diameter mirror the capability to produce the
results we see in our searches of the universe.

Let's not confuse the  "pass through" characteristic of superb optical
glass with the "hard as granite"  characteristic of the glass used as the
bedrock of astronomical mirrors.







George Berger
gberger@his.com