Since this is a subject of some interest here I think its more or less on topic. 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. I had known that RCA was interested in anti-reflection coatings and their people had done work on chemically deposited coatings as early as the late 1930's but not that they were doing rather advanced vacuum coating very early on. I think they must have had applications other than photographic sound recording although the control of flare is quite important in that application. I will post specific patent numbers later if anyone is interested but anyone can find them by searching for Glenn Dimmick in the Google patent search engine. I no longer have easy access to the RCA research laboratories house organ _The RCA Review_ but I suspect there may be more about the work there.
--- Richard Knoppow Los Angeles, CA, USAdickburk@xxxxxxxxxxxxx
--- Rollei List - Post to rollei_list@xxxxxxxxxxxxx- Subscribe at rollei_list-request@xxxxxxxxxxxxx with 'subscribe' in the subject field OR by logging into www.freelists.org
- Unsubscribe at rollei_list-request@xxxxxxxxxxxxx with 'unsubscribe' in the subject field OR by logging into www.freelists.org
- Online, searchable archives are available at //www.freelists.org/archives/rollei_list
