Almost all UV sources used in UV-fluorescence photography work are based on mercury vapor lamps with external filters to narrow down their emissions to a certain range. Different materials respond to different wavelengths differently, so a single wavelength lamp does not usually suffice to explore the field of UV fluorescence photography. Most commonly, enthusiasts would have a lamp for Long-Wave (LW) and one for Short-Wave (SW) use, or alternatively a dual-wavelength LW and SW lamp with individual power control. More advanced users also have a lamp that can emit Medium-Wave (MW) UV because a few materials respond very distinctly to its wavelength. The selection depends on the user’s specific interest – 85% of fluorescent minerals glow under SW-UV light, but LW-UV should be used for all live specimens because of the biological damage that would be caused by shorter wavelength UV.
Quality filtered lamps tend to be expensive, but their price is often justified not only because of the cost of tubes, but also because of the high cost of filter glass – especially the one for the shorter wavelengths. A more economical proposition is to build your own lamp, and you may follow the schematic of this new whitepaper as the basis for a professional-quality 18W lamp that covers the full range of wavelengths.
Link to whitepaper: prutchi-diy-sw-mw-lw-uv-lamp
The following figure shows pictures of Hackmanite from Bancroft, Ontario, Canada taken using this diy lamp: a) White light photograph; b) reflected near-UV with Baader-U and long-wave illumination; c) fluorescence with wideband (LW, MW and SW) excitation; d) long-wave UV excitation; e) fluorescence with mid-wave UV excitation; f) fluorescence with short-wave UV excitation.
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