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> I have been using a Damar, 25w, blb, spiral, CFL in a parabolic shop light reflector. This bulb has peak emission at 352 nm. that falls off to ~ 0 at 300 nm and 400 nm. I thought this bulb had nice output: WRONG! The measurements across the bottom of the reflector, at 3" varied from 1.1mw/cm2 to 3.6 mw/cm2 (at the center). I found some data on a NEC blacklight T10 which is made in Japan and I think available in Australia: at the face, 4.82 mw/cm2, at 3", 0.96 mw/cm2, at 6", 0.55 mw/cm2. These data are consistent with my spiral blb.
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That's an interesting article, lots of good info. Keep in mind that there are ∗many∗ different types of metal halide lamps, each with different spectral characteristics. Some incorporate much better UV blocking than others as well.
I'm not surprised about the BLB lamp, the Woods glass used in filtered blacklights absorbs much of the useful UV output as well. When I do UV exposure I use an unfiltered BL UV lamp intended for a bug zapper. I don't have proper measurement gear but it works fine and produces consistent results, although I mostly use toner transfer these days.
> I then measured the output from a plain old 20w 120v halogen under cabinet puck with its glass cover which said UV Filter-001. At 3" the reading was 22 mw/cm2 and with the glass cover taken off the reading was 25 mw/cm2. This was quite startling. Halogen bulbs generally have a bad reputation for producing UV. It also implies that all of the UV fluorescent DIY exposure boxes are inefficient designs. Moreover, I think when bulb manufacturers say "UV blocked" they really mean UVB, but do not say so. The percent reduction with the glass shield is about the same content of UVB as in the full UV spectrum for a halogen bulb.
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> I am awaiting delivery of my metal-halide unit which is pictured here,
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> http://www.championlighting.com/product.php?productid=9000100&cat=0&page=1
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> Unfortunately, I will probably not be able to report an intensity that is greater than 40 mw/cm2. This is the maximum reading for my meter. Moral, read the specs carefully before buying...
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> Baxter
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> > Metal halide lamps produce relatively little UV, the halide salt vapors absorb it. A clear mercury vapor lamp produces much more, while the bare quartz arc tube from one is a very powerful UV emitter, the latter will produce large amounts of ozone.
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