WO fluorite doublet design

I've just shone a green laser into the objective glass of my ZenithStar FD. The laser light scatters in both lenses, which means that neither of them is made of fluorite crystal (to my relief). I can also see that the front lens is negative and the second one is positive, and there is a rather wide, a few mm, air gap.

The colour correction is very good, I can see a small (5-7 Airy disc diameters) weak violet halo on bright sun reflexions and also on very distant luminiscent lamps, but I cannot see any colour on Moon or Vega.

Would anyone care to comment on the design?

Dmitri

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William Optics do not claim to use Calcium Fluorite, he told us, this Fluorite douplet use a modern chinese fluorite, whatever he means with that.
The design is good in any case, as good as the Sky 90 who use Caf2, so nothing to worry about

clear skies
Markus