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the aim of fluoride glass is the same as fluorite.

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Arek,

Now I am confused again (as I often am).

I thought the term fluoride was used to describe a molecule that contained fluorine atoms such as calcium fluoride, which consists one atom of calcium and two atoms of fluorine. A lattice of calcium fluoride molecules makes the fluorite crystal used in some lenses.

So I wonder what fluorine-containing-molecule is being added to the glass to give it fluorite properties? Maybe it's the secret ingredient in FPL-53? There has been periodic discussion and debate on other forums whether or not Takahashi is using pure fluorite crystal or some special glass mix, since green laser light apparently is visible in some (but not all) Tak objectives.

One thing that is agreed upon is that pure fluorite is more fragile than glass, which is why it is usually the inside element of a doublet. In Takahashi's FS series it was out front, perhaps why they used a variation (if in fact they did).

If anyone needed help getting to sleep to night, I'm glad I could help.



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Clear skies, Milt

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