Re: Thorium in old lens?

[Tad Blanchard <Tad.M.Blanchard.1@gsfc.nasa.gov>]

Thorium in lenses is supposed to increase the refractive index.  NASA has
several of these in high-altitude cameras.  Radiation levels are as you
described.



At 10:01 AM 2/15/99 -0600, you wrote:
>
>
>
>    Hello.
>
>    I have recently come across a lens system with the term "Rodenstock
>    TV-Heligon" inscribed on it.  What is interesting about this lens is
>    that it has a contact gamma field of about 2.5 mR/h.
>
>    I would like to determine the source of this radioactivity.  Has
>    anyone ever heard of such a radioactive lens?  Any ideas as to why a
>    lens would be radioactive?
>
>    Laura Boksman
>
>
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