# UVC fluorecent light



## The_LED_Museum (Jul 16, 2004)

Just thought I'd share this, and ask if anybody else here has a shortwave UV lamp.

This is a shortwave (254nm) fluorescent UVC lamp that I saw and purchased on Ebay.
The tube is unfiltered, and emits a light blue visible glow.






Here's a photograph of the tube itself, while energized.
This photograph makes the glow appear significantly brighter and whiter than it really is.





And here's a photograph, showing the warning printed on the flurorescent tube glass itself. This photograph renders the brightness much more correctly; though the color is a little too violet.

There is a faint odour of ozone (O3) where the lamp is exposed by a cutout in the protective window, and the lamp is activated. That is evidence that some "vaccume UV" (wavelengths shorter than 200nm) is being produced; not unexpected considering the nature of the source.





Here's a photograph of an orange UPS label and a green USPS label fluorescing under the UVC radiation from this light.


----------



## jtr1962 (Jul 16, 2004)

Those are what is used in EPROM erasers. When the EPROM eraser is operating the tube emits a bluish glow which is visible through an indicator window. The tube itself is clear. Most devices that use these tubes have a safety interlock to prevent the tube from operating when the door or tray is open.


----------



## PhotonWrangler (Jul 16, 2004)

[ QUOTE ]
*jtr1962 said:*
Those are what is used in EPROM erasers. When the EPROM eraser is operating the tube emits a bluish glow which is visible through an indicator window. The tube itself is clear. Most devices that use these tubes have a safety interlock to prevent the tube from operating when the door or tray is open. 

[/ QUOTE ]

They also use those to sterilize water; there's at least one consumer-style water purifier that employs a UVC lamp inside.

They used to use these in bowling alleys to disinfect bowling shoes after they were returned. The shoe counter always had an aroma of ozone...
/ubbthreads/images/graemlins/icon15.gif


----------



## wholeflaffer (Jul 16, 2004)

[ QUOTE ]
...The shoe counter always had an aroma of ozone...
/ubbthreads/images/graemlins/icon15.gif 

[/ QUOTE ]

Yeesh, I'd hate to work near that. Not just the shoe factor /ubbthreads/images/graemlins/faint.gif, but ozone gives me a headache /ubbthreads/images/graemlins/sick.gif, and I'm pretty sure long-term exposure at smellable levels isn't good for you /ubbthreads/images/graemlins/jpshakehead.gif.


----------



## Draco_Americanus (Jul 16, 2004)

that hurts my eyes just looking at the picture! 
I have a filtered UVC light that I use for my rock collection. I assembled the light my self useing a 15watt germicidal lamp, 15 watt cheap blacklight fixture becuse the housing was black and has an aluminum reflector. I used a hunk of filterglass I bought from UV Systems and held that in place with a custom made holder from sheet aluminum and black silicone RTV, During the final stages I had the light energized so I could fill in any missed spots in the RTV. even with that short duration I paid for it for a day or so after. Blured vision and that sandblasted feeling whent away the next day luckly. I also have a dual band 4 watt filtered light for field use. This weekend I will post pics of that light as the bulb is neat. 
I would pop a filter on that light, it would be very usefull then!


----------



## Draco_Americanus (Jul 16, 2004)

My glowing rocks


----------



## PhotonWrangler (Jul 16, 2004)

[ QUOTE ]
*Draco_Americanus said:*
I also have a dual band 4 watt filtered light for field use. This weekend I will post pics of that light as the bulb is neat. 

[/ QUOTE ]

Is t hat the bulb that's coated with a UVA phosphor on one half of the bulb and clear on the other half?


----------



## PhotonWrangler (Jul 16, 2004)

[ QUOTE ]
*wholeflaffer said:*
[ QUOTE ]
...The shoe counter always had an aroma of ozone...
/ubbthreads/images/graemlins/icon15.gif 

[/ QUOTE ]

Yeesh, I'd hate to work near that. Not just the shoe factor /ubbthreads/images/graemlins/faint.gif, but ozone gives me a headache /ubbthreads/images/graemlins/sick.gif, and I'm pretty sure long-term exposure at smellable levels isn't good for you /ubbthreads/images/graemlins/jpshakehead.gif. 

[/ QUOTE ]

I used to have an office that was right next to a copier machine. That machine always produced a little cloud of ozone when it was operating, I believe from the high voltage drum charging wires. I used to get headaches from being near that machine. /ubbthreads/images/graemlins/sick.gif Fortunately I've moved from that area, and the current machines seem to produce much less ozone when they're operating.


----------



## mattheww50 (Jul 16, 2004)

Two points. Most copiers and laser printer now have exit filter with activated charcoal to catch the ozone produced, it reacts with the filter 2 ozones end up as 3 O2's..

UV lamps also have very finite lifetimes (much much shorter than standard fluoro's for some reason). I am not sure why, but I found after about 18 months, our UV Eprom erasers just didn't work very well (erased Eprom's would turn out to have residual random data in them). My guess is the useful life was perhaps 1000 hours. I'd put in a new lamp, and presto, the eproms would erase fully in the standard erase time. The Eproms required a certain total UV energy to be delivered to erase, and as the lamps age, that energy fell off pretty rapidly.


----------



## Draco_Americanus (Jul 17, 2004)

The quartz or special glass the tube is made from is degraded (solarized) by the UV light and becomes less trasparent to that wavelength or light. The expensive filter glass for my light and other filtered mineral lights use have the same thing happen to them. It sucks but I guess there can be nothing done about it. 
Better quality filter glass and better bulbs do last longer.


----------



## Draco_Americanus (Jul 17, 2004)

yup! thats the bulb! Then the light has a cover that has both types of filter glass. I hope to find lots of neat rocks with it this summer. Runs from 4 aa batteries or the included ac adaptor.


----------



## PhotonWrangler (Jul 17, 2004)

[ QUOTE ]
*Draco_Americanus said:*
The quartz or special glass the tube is made from is degraded (solarized) by the UV light and becomes less trasparent to that wavelength or light. The expensive filter glass for my light and other filtered mineral lights use have the same thing happen to them. It sucks but I guess there can be nothing done about it. 
Better quality filter glass and better bulbs do last longer. 

[/ QUOTE ]

What Draco said. /ubbthreads/images/graemlins/thumbsup.gif /ubbthreads/images/graemlins/grin.gif


----------



## The_LED_Museum (Jul 17, 2004)

[ QUOTE ]
*PhotonWrangler said:*
They used to use these in bowling alleys to disinfect bowling shoes after they were returned. The shoe counter always had an aroma of ozone...
/ubbthreads/images/graemlins/icon15.gif 

[/ QUOTE ]
I don't remember smelling ozone at the shoe counter at Channel Bowl in Juneau AK. in the 1970s and 1980s; they sprayed something into the shoes with an aerosol bomb.
Maybe they realised UVC was bad before other bowling alleys did.


----------



## PhotonWrangler (Jul 17, 2004)

[ QUOTE ]
*The_LED_Museum said:*
[ QUOTE ]
*PhotonWrangler said:*
They used to use these in bowling alleys to disinfect bowling shoes after they were returned. The shoe counter always had an aroma of ozone...
/ubbthreads/images/graemlins/icon15.gif 

[/ QUOTE ]
I don't remember smelling ozone at the shoe counter at Channel Bowl in Juneau AK. in the 1970s and 1980s; they sprayed something into the shoes with an aerosol bomb.
Maybe they realised UVC was bad before other bowling alleys did. 

[/ QUOTE ]

In the bowling alleys where I saw the UVC lamp in operation, it was close enough to the front counter that it was obvious what it was, both by appearance and odor. This was back in the days when they used to use those little "Ozone bulbs" in hand dryers in public restrooms.


----------



## Aloft (Jul 26, 2004)

I'm curious about the "filter" for these flourescent tubes. Does it filter out visible light, so it's difficult to see if the light is operating unless something in front of it is flourescing?

I'm interested in invisible inks and steganography. If the filter works by filtering out visible light but letting UV through, would it be possible to flouresce invisible ink using sunlight and a filter, dispensing with the artificial UV source altogether? Or am I describing a perpetual "free lunch" machine? Any opinions are welcome, I'd like to experiment. . .


----------



## PhotonWrangler (Jul 26, 2004)

[ QUOTE ]
*Aloft said:*
I'm curious about the "filter" for these flourescent tubes. Does it filter out visible light, so it's difficult to see if the light is operating unless something in front of it is flourescing?

I'm interested in invisible inks and steganography. If the filter works by filtering out visible light but letting UV through, would it be possible to flouresce invisible ink using sunlight and a filter, dispensing with the artificial UV source altogether? Or am I describing a perpetual "free lunch" machine? Any opinions are welcome, I'd like to experiment. . . 

[/ QUOTE ]

Good questions, Aloft. Even though it's UVC, there's still a faint deep purple glow that is emitted from a filtered lamp. It's considerably dimmer than an equivalent wattage UVA blacklight, but it's still noticeable. I think that part of this is because a UV filter isn't perfect and allows some visible light through, and partly because UV light flouresces the eyeballs. Go into a bathroom with a black light and turn out the visible lights while you turn on the blacklight. Your eyes will glow! /ubbthreads/images/graemlins/ooo.gif

As far as the sunlight experiment, it would work. This is why those "whiter-than-white" fluorescent dyes work for clothes - and that fluorescent dye is why modern detergents and your socks glow under black light.


----------



## Aloft (Jul 26, 2004)

[ QUOTE ]

As far as the sunlight experiment, it would work. This is why those "whiter-than-white" fluorescent dyes work for clothes - and that fluorescent dye is why modern detergents and your socks glow under black light. 

[/ QUOTE ]

Great, now I will have to try to find one. I noticed that a lot of rock and gem shops sell these as accessories to the tube type UV lights (one of which I should have anyway). But are any available anywhere else, or in a more convenient form factor?


----------



## PhotonWrangler (Jul 26, 2004)

[ QUOTE ]
*Aloft said:*
[ QUOTE ]

As far as the sunlight experiment, it would work. This is why those "whiter-than-white" fluorescent dyes work for clothes - and that fluorescent dye is why modern detergents and your socks glow under black light. 

[/ QUOTE ]

Great, now I will have to try to find one. I noticed that a lot of rock and gem shops sell these as accessories to the tube type UV lights (one of which I should have anyway). But are any available anywhere else, or in a more convenient form factor? 

[/ QUOTE ]

All of the shortwave UV lamps are tube-type. They all employ mercury-vapor as the UV-generating medium. They have yet to develop a shortwave UV LED; I think that's still a ways off for a number of reasons.


----------

