As recognized, this entire loose thread of lanthanides, actinides,
optical coatings, etc. was still state-of-the -art 'spook' science - -
highly classified - - in the era when Qlympus and others introduced
these lenses. One of the fascinating stories of post-WW II technology
development was creating separation methods for individual elements of
the rare earths. Actually, they are not so 'rare' , just rarely
separated. Some are members of the naturally radioactive decay chains
others not. The challenge was how to separate when all members of a
chemical family have the same outer orbital electron configuration.
Today, any of them can be purchased in extremely pure form and in
relatively large quantities.
Bill Hunter.
On Saturday, August 9, 2003, at 08:34 PM, Chuck Norcutt wrote:
Some of these were mildly radioactive themselves or may have contained
contaminants that were radioactive. The contaminants can vary
considerably by glass batch so otherwise identical lenses can vary
considerably in their degree of radioactivity and amount of yellowing
over the years. In later years manufacturers learned to control the
contaminants.
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