[rollei_list] Re: Early Lens Coating
- From: Marc James Small <marcsmall@xxxxxxxxxxx>
- To: rollei_list@xxxxxxxxxxxxx
- Date: Mon, 04 Jun 2007 19:06:50 -0400
At 06:29 PM 6/4/2007, Richard Knoppow wrote:
> I've recently been using Google Patents to search sound
>recording patents. One of the pioneers is Glenn Dimmick who
>worked for General Electric and later RCA. Dimmick is known
>mostly for his work on the mirror galvanometer type light
>modulator used by RCA for its sound on film system. It turns
>out that he also did considerable research into lens and
>mirror coating. I found several patents issued to him,
>mostly from the mid to late 1940's for vacuum coating
>methods and, what is especially interesting to me, multiple
>layer coatings for both mirrors and lenses. I had previously
>thought that the use of coating stacks was a much more
>recent development, but obviously its not.
Thanks, Richard. VERY interesting.
Multiple coatings of various types were developed
within the amateur astronomy community starting
in the late 1930's; one of the leaders of this
interest was Russell W Porter, the inspiration
for the Hale 200" telescope at Mount Palomar in
California. The problem was durability and this
led to some work being done on such coatings in
the 1950's at Mount Wilson by Robert Leighton,
the same fellow who cobbled together an
electronic eye and a movie camera to make
stunningly good color photographs of the planets,
a remarkable achievement with the rather crude
electro-mechanical technology of the time. (See
SCIENTIFIC AMERICAN's "The Amateur Scientist"
column for June, 1956, for a discussion of the
photography; this was one of the relatively few
such columns on astronomy run by C L Strong after
he took over following the untimely death of Ingalls.)
The later work done by Asahi and Zeiss which led
to the SMC and T* coatings was a development of
coatings sufficiently durable to allow use in lab
and technical gear and on camera lenses.
Marc
msmall@xxxxxxxxxxxx
Cha robh bàs fir gun ghràs fir!
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