UV question

I picked up some UV pass glass (they just called it cobalt color) and had a question about the wavelength. I cut it down and threw it in my TL. When I shine it on dark objects, I see a really faint reddish purple - not bright at all. When it hits something white or light in color, it reflects REALLY bright purple light. Now, I'm used to UV lights putting out this brighter purple light right from the source, rather than having to hit a light object to reflect it. Am I making sense? Why is the light a really dim dark reddish purple until it hits something that reflects the brighter VU looking light I am used to. Does this mean it has a more pure UV output????

Sorry, thought this qualified as a mod...

It's difficult to categorize, thus the Cafe. But it's an interesting subject. /ubbthreads/images/graemlins/cool.gif

I'm not at all an expert, it seems to me that it is a filter that passes only UV light. And what you're seeing is objects fluorescing from it's output. I would also consider wearing safety glasses while using it until you find out more. I wouldn't think the light is more pure, because you're not describing it as violet.
I assume TL is Tiger light, right? What I wonder, is how much UV does an incandescent bulb emit? Is that a xenon bulb? And I also wonder how it compares to UV only lights. For instance, if you can get a great deal of UV light from an incandescent bulb with a filter, why buy an expensive UV only light?

Where can I find UV protective eyewear? I use an Arc AAA in UV to checks minerals. Thanks.

I am no expert on the subject but I believe shankus is correct in stating that the pass filter is just that; it is allowing the UV bands of light through and either reflecting or absorbing the other wave lengths. In the absence of the visible spectrum, I think you are seeing that portion of your light that is UV, reacting with fluorescent items. The color of light from the source that you are seeing is likely the near UV that is getting through the filter.

- Don

And its UV emission should be no more dangerous that that from an unfiltered TL. I wonder what the wavelength/power distribution curves for "white" Krypton and High pressure Xenon lamps are.

Larry

I suspect that the lensed TL is slightly more hazardous than the original due to the lack of pupil contraction and the likelyhood to use it under subdued illumination.

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2dogs said:
Where can I find UV protective eyewear? I use an Arc AAA in UV to checks minerals. Thanks.

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I think any hardware store or Home Depot or Lowes type establishment could hook you up with some. The Uvex brand claims, even on their clear lenses, to block 99.9% UV <400nm.
I have a pair of Uvex, and they block UV well. I also have a $5 pair I bought in the college bookstore after loosing mine, and they block the same. I think most sunglasses you find today probably absorb or reflect UV, but for your purposes, you might want a pair of clear safety glasses.

Just take your Arc with you to the store, with something you know fluoresces, and shine the UV through the lens at the normally fluorescent item. If you don't see the glow, you're good to go. /ubbthreads/images/graemlins/blush.gif

As a side note, I noticed awhile ago that you can look at very bright lights through a CDR (or any CD with no label), and you can safely see the filament or die. And it seems to block a lot of UV, although not as much as my glasses. /ubbthreads/images/graemlins/thumbsup.gif



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Ferrous said:
I suspect that the lensed TL is slightly more hazardous than the original due to the lack of pupil contraction and the likelyhood to use it under subdued illumination.

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I agree. That is why it is harmful to wear sunglasses that aren't UV blocking. That pupil opens up wide and the eye soaks up everything available to it.

Use caution !!!!!
You might want to test your safety glasses.
I just shined my Inretech UV thru a pair of AOSafety glasses that are marked "Lens absorbs 99.9% UV" and I saw very little attenuation of the objects fluorescing. /ubbthreads/images/graemlins/mad.gif
Nothing even close to 99.9%. /ubbthreads/images/graemlins/thumbsdown.gif

Thanks for the warning snuffy. I saw your other post in the fun things with UV thread. Making the rounds, and "looking out" for our eyes, right on.
That is scary. You will return them, right? Perhaps an email to the manufacturer, as well?

My Uvex glesses seem to work, although I wonder what I'd see using that monster Inretech adaptor you have. /ubbthreads/images/graemlins/eek.gif /ubbthreads/images/graemlins/cool.gif /ubbthreads/images/graemlins/smirk.gif

Thanks for all the info. I did notice my eyes were a little irritated after using it for a while (looking for dog "accidents").

<font color="800080">I just shined my Inretech UV thru a pair of AOSafety glasses that are marked "Lens absorbs 99.9% UV" and I saw very little attenuation of the objects fluorescing.</font>

<font color="000080">As far as I`m aware, it`s not just UV wavelengths that will cause flourescence in suitably coloured objects. Shine a blue LED with a bottom wavelength of around 450nm at a dayglo object and it`ll glow real good. Even shine a turquoise light at some dayglo yellows, pinks and oranges and you`ll see a noticeable flourescence.

I would suspect your glasses are just fine, and the LEDs used in the Inretech device are just emitting a fairly wide range of wavelengths including plenty above 400nm or thereabouts, which will get through your glasses but aren`t as dangerous to your eyes as the shorter wave UV.</font>

/ubbthreads/images/graemlins/eek.gif

Chris M,
Thanks for the insight. /ubbthreads/images/graemlins/thumbsup.gif

You should test it with a Security UV marker pen, or some money, or your credit card.

Thanks shankus. I'll try to find some today and report the results.

Doesn't have to be UV to make some things flouresce, a green laser will drive red and orange GID and Dayglo silly..

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I picked up some UV pass glass (they just called it cobalt color) and had a question about the wavelength

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Cobalt glass is sometimes mistaken for Woods Glass, cobalt glass, using the matal cobalt in the mix, was first used by the Romans and is pretty blue colour and was once used to distiguish bottles containing poison.

Woods Glass is the UV pass filter used on blacklight blue lamps which contains nickel oxide named after Prof Robert Williams Wood:

Prof Robert Williams Wood
'The modern wizard of the laboratory'

http://msp.rmit.edu.au/Article_04/06.html

Thanks to Bart Lederman for this and addiotional info, Woods glass also transmits Infra Red but blocks most of the visible range, the Kodak Wratten 18A filter has a very similar transmittance:

http://msp.rmit.edu.au/Article_01/06.html

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Where can I find UV protective eyewear? I use an Arc AAA in UV to checks minerals. Thanks

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One thing to look out for is some minerals will only fluoresce with shorter wavelength UV B light, below what an LED can generate, for thsi you need fluro lamps of the correct wavelnght and eye protection with these is strongly reccomended.

Yes, there is such a thing as visible light fluoresecence so suitably doped plastics will block below 400nm protecting your eyesight, but some things may still fluoresce even through these plastics.

HTH
Adam

Or just a naked mercury discharge lamp in a quartz glass tube to let out the 296nm (from memory) lines. very UV.

Thinks its nearer 253nM thats the strongest mercury line, the answer will be here somewhere ;-)

http://members.misty.com/don/uvbulb.html#sp

Adam