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UltravioletPhotography

Spectra of a few fluorescent lamps


enricosavazzi

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enricosavazzi

post-60-0-06622800-1488822645.jpg

 

violet: 85 W photo CFL. (no significant UV to measure here)

green: Exo Terra ReptiGlow 10.0 UVB 26 W (for reptile terraria, mentioned in another recent post). UVA+UVB Irradiation intensity at 50 cm distance (separately measured) 13 μW cm-2.

red: enamel hardening UVA CFL. 128 μW cm-2 (but the fixture contains a reflector).

blue: compact "blacklight" tube. 124 μW cm-2.

 

The largest sharp peaks are the main Hg emission lines, so naturally they are at the same wavelengths because all these lamps are built around the same mercury discharge.

 

The differences are mainly due to the different phosphors and absorption by the glass, phosphor and/or or paint coating. The Photo CFL emits virtually no UV (as desirable for this use) except for a low intensity 365 nm. The Exo Terra has a relatively broad fluorescence band between 290-340 nm, the only one among the tested lamps (but the UV emission intensity is very small). The fingernail enamel hardening lamps have a relatively high fluorescent emission band between 365 and 400 nm, also potentially useful. The blacklight CFL spans virtually the whole UVA, although the 365 nm spike is strong.

 

Fortunately, none of these lamps emit below 290 nm.

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Thanks Enrico. Here is a picture of the graph on the side of the box my Reptile UVB 200 26W came in, which is much clearer to read than the graph they show online.

This may be a slightly different bulb model than what you have, but looks similar to the graph you show (green).

post-87-0-27535300-1488859655.jpg

 

Here are my Black Light and UVB 200:

http://www.ultravioletphotography.com/content/index.php/topic/2145-uvex-ultrasonic-9302045-goggles/page__view__findpost__p__15414

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Enrico, thank you for this interesting chart of spectral properties for the various mercury lamps.

 

As a female, I've had my hands under those nail gel hardening lamps a couple of times. Made me squeamish, of course, given our constant warnings about the hazards of UV. :D

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Nice job Enrico!

Do I assume correctly that your separate UV irradiance measurements were done with your new meter? The combination of a spectrometer and a radiometer provides much more meaningful information than either instrument used alone.

 

Those reptile lamps are somewhat unique in that they are designed to provide good color rendering for viewing specimens while at the same time providing UVB needed for vitamin D sufficiency.

 

Andrea, as long as you use a reputable nail salon who only buy OEM replacement lamps the risk is negligible. Even less risk from the LED based nail curing systems.

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enricosavazzi

Nice job Enrico!

Do I assume correctly that your separate UV irradiance measurements were done with your new meter? The combination of a spectrometer and a radiometer provides much more meaningful information than either instrument used alone.

Yes, that is how i did it. I placed the spectroscope fiber with cosine corrector directly in contact with the surface of the tube and recorded the spectrum, then placed the meter 50 cm from the tube and oriented the meter sensor directly toward the lamp. The cosine corrector of the meter makes it quite insensitive to moderate changes in orientation toward the ilumination source.

 

The spectrometer can store internally up to 64 spectra, then send them to the PC in a single batch. I usually configure the spectrometer to use an exposure time between 10 and 50 ms for each spectrum (depending on the lamp strength), and to average among 10 exposures to try and eliminate any bias due to flickering. The spectrometric software on the PC takes 2-3 seconds between successive batch readings, so there are obviously pauses in the process. The spectrometer probably has a built-in Arduino or similar CPU board, which means it takes some time for it to spit out the data through the USB interface. Most likely the PC software does all the computing. I know for sure that the spectrometer stores its factory calibration data in onboard flash memory, and the PC reads it each time the spectrometer is plugged into the USB socket. It is very likely that the spectrometer sends only raw pixel data to the PC, and the PC software then applies the calibration data to normalize the height and wavelength axis of the spectra.

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enricosavazzi
Thanks Enrico. Here is a picture of the graph on the side of the box my Reptile UVB 200 26W came in, which is much clearer to read than the graph they show online. This may be a slightly different bulb model than what you have, but looks similar to the graph you show (green).

You are right, it may not be the same model and the spectra are similar but not the same. I now have one like yours on order, and will post the spectra of the two lamps once the new one arrives.

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