Light (and UV) output of flourescent tubes.

[matthyaouw]

Hello all,
Long time no see.

I am hoping to find someone with knowledge of light output (in particular UVA output) of fluorescent tube lights. I have 2 questions:

-Should I expect the light output of a 20 watt CFL bulb and a 20 watt 2 foot long fluorescent tube to be the same, or different (allowing for variation between manufacturers)?

-Will BL lights (such as for bug-zappers) emit more UVA than BLB lights (such as for security checking passports, raves etc)?

Basically I need a source of UVA light for photographic printing and am trying to find the best way to light an area the size of A3 paper as brightly as possible for relatively little cash. I have a couple of CFL BLB lamps but am considering replacing them as they are a bit on the weak side for me. Mercury vapour is out of the question due to cost, so I think I'm pretty much confined to fluorescent. Presence or absence of visible light is not an issue. The collective knowledge of google seems quiet about the subject and I am unsure where else to ask

Thanks in advance,

Matt

 

[Baluncore]

Fluorescent lights have some mercury to provide the UV spectrum that then drives the phosphor to fluoresce at longer wavelengths.

Have you considered the new UV Blacklight LEDs? 3W, UV at 395nm.

 

[mjhilger]

I was going to suggest the UV LED also, but I didn't know how much intensity and the exact wavelength you might need. However, I picked up one of those UV flashlights off ebay http://www.ebay.com/itm/UltraFire-WF-501B-LED-Flashlight-375NM-UV-Ultra-Violet-Blacklight-Torch-18650-/161161947959?pt=US_Flashlights&hash=item2586002b37 for around $12. Might be worth a try to see how close it gets you. Most of those lights use a Li-ion 18650 cell by the way.

 

[Baluncore]

Google “germicidal lamp”, also known once as actinide tubes, they produce UVC which is dangerous if not treated with respect. They are probably overkill for your application.

http://en.wikipedia.org/wiki/Germicidal_lamp

Also: Graphic Arts/Printing Lamps.
http://stores.ebay.com.au/Lights64/...l?_fsub=6&_sid=46217276&_trksid=p4634.c0.m322

 

[mjhilger]

Also, we used to use UV source to erase the eproms. I have a home made unit I built with a 4" UV tube (dangerous type - clear glass) you did not want to look at it for very long. (My homemade unit worked better than the $100 unit we had because I could load more eproms in it. (Used to change the program and test faster than the erase time) I'm sure many of those can be found, but again I don't know if that meets your intensity, wavelength or area requirement.

 

[matthyaouw]

Thanks for the input. I have gone with a couple of blacklight fluorescent tubes for the moment mainly because I don't seem to be able to get much else near home. LEDs could work but it seems many are more violet than ultraviolet and I don't want to spend an age wiring something up that might not work. I'm avoiding germicidal lamps because I think I need UVA rather than UVC.

 

[RBTO]

You mention "photographic printing". Are you exposing photoresist or Azo materials? If that's the case, blacklight tubes should work fine. It's best to stay away from the shortwave UV entirely due to hazards associated with shortwave UV, and most materials respond to longwave UV pretty well (some caution is warranted there also). In any case, you can probably compensate by using longer exposures since exposure of most of those materials doesn't call for UV at a specific wavelength, and the sensitivities have a fairly wide span of wavelengths. You may have to adjust the spacing and distance of your tubes to prevent hot-spotting (more exposure in one area than another). You can test for the proper exposure by making a series of test exposures using varying lengths of time to see what works best.