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Re: NEON- Re: color checker??
Dear Matt,
Soda or pyrex will be transparent for 350nm UV radiation, but will
behave like black cloth for 254nm.
So you can never excite fluorescent powders throgh any glass except
pure quartz. All powders are primary excited by 254nm, only some mixed
powders may have additional phosphorescent compunds which are excited by
the 350nm range.
When I'm unsure in a broken unit's color, I light into the tube with a 244nm
UV laser. So I can see the pure phosphor, but not the tube's color after
been pumped. To get the right color, you have to add the grren and blue
components of the mercury discharge. No color checker can afford this,
some parts of the phosphors are excited by the free electrons present in the
tube. Color checkers can only be a rough estimation.
Marcus
> For one thing, it seems that
> >these Mineral Lites are of short wavelength and won't pass easily through the
> >wall of the neon tubing.
> >Jeff Golin
> >
> >
> Jeff,
> I don't know if you work in all soda, but the uv light will amost always be
> blocked by leaded glass. I Have never seen a color checker that will light
> up a tube other that on the end.
> The story is different of course if you are working in say, soda or pyrex.
>
> matt
>
>
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