UV lights and eye damage

Leef

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Do the LED UV lights (e.g. from the Shoppe) put out enough damaging light to be really dangerous to the eye, or is the warning not to shine them in the eyes overkill? If they really can be harmful, are there protective glasses that filter out the UV but let most or all of the visible reflected light (e.g. from a scorpion or a mineral) thru?
 

lotsaluck

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The answer really depends on your viewing length and angle. ALL light can damge your eyes, the big problem with the UV's (and for that matter IR's) is that your eye does not have the gag reflex it has for visible light so an over exposure is easy to get by looking at it to long with dialated pupils. Also UV light exposure is a cancer risk, but UVV and UVA risks are minor for cancer as far as is known.

Now of course you will find challenging opinions on this but being a large producer of very high output led UV lights we have had the legal department look pretty hard at the concern. The worse case I have heard of is one guy starring right at one while on, trying to figure out its construction under a magnifying lens. He devolped an eye burn similar to welding burn that corrected itself in a day. Same thing would happen with a white or red LED if you starred at it long enough.
 

David_Campen

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Not true... Many plastics will but most will not unless certain inhibitors are added to the resin during its casting.
The additives are there to absorb the UV instead of the plastic because without the additives it would be the plastic that would absorb the UV and suffer damage.
 

Icebreak

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lotsaluck said:
Snip...being a large producer of very high output led UV lights we have had the legal department look pretty hard at the concern...
What do you guys make? Linky?
 

soffiler

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David_Campen said:
The additives are there to absorb the UV instead of the plastic because without the additives it would be the plastic that would absorb the UV and suffer damage.

First of all, basically ALL safety glasses on the market today are made of polycarbonate because of it's excellent resistance to impact. So in reality we don't need to talk "plastic" generically, because we know exactly which plastic it is. Now, clear polycarbonate has an annoying tendency to turn yellow-ish when exposed to UV; therefore, the majority of clear polycarb materials have UV inhibitors added by the manufacturer. So it boils down to what sounds like an oversimplification but it holds true in the real world: safety glasses will inhibit UV. Taking it one step further, amber safety glasses are often employed to enhance the fluorescence effect. This works because fluorescence is generally a yellowish or greenish which is not blocked by the amber filter, while it does remove purplish and bluish light. So instead of yellow against purple background, you put on the glasses and get the same yellow against a nearly black background. It may not sound like much but in practice it will take a dull glow and make it appear much brighter due to the contrast enhancement. And, at the same time, you're getting protection for your eyes from UV exposure as a fringe benefit.

Steve Offiler
VP of Engineering
Central Tools, Inc.
 

Leef

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Good information. Thanx, all. I'll be sure to get some amber safety glasses to put on the scorpions before I spot them. :naughty:
 

xenopus

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We have found that clear safety glasses with "UV Blocking" stickers on them do not provide protection from most of our flashlights at 380nm and above.

If you don't have a UV power meter, you can do a simple test -- insert and remove the lens between the flashlight and a fluorescent target. If the observed fluorescence is largely unaffected, then UV is penetrating the glasses.

Piers
 

Icebreak

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lotsaluck -

Interesting device. Thanks for the link.

xenopus -

Always good to hear from you in these threads. Thanks for your continued, enlightening posts.

- Jeff
 

xenopus

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Icebreak said:
lotsaluck -

Interesting device. Thanks for the link.

xenopus -

Always good to hear from you in these threads. Thanks for your continued, enlightening posts.

- Jeff

Jeff -- thanx! Just haven't been as active lately, sorry :)

Talking of UV lights, I just took my 5-year old caving (in Airman's Cave, Austin, TX) for 3 hours of crawling with an average 18 inch ceiling!). Had a great time, but didn't think to bring any ultraviolet flashlights. I don't know if limestone caves (either in general, or this one) are indicitive for growth of things that fluoresce, but it would have been interesting to see. Maybe next time. There were a number of slimy salamanders which really made his day, though!

http://www.xenopuselectronix.com/Caving/Airmans/05_21_06_1207.JPG

Piers
 
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Oracle

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The longer wave UV LEDs are less dangerous than short wave UV, but not completely safe. UV exposure will cause cataracts.

Basically don't look directly at the LEDs, but you should be okay looking at what's being lit up by the UV.
 

Icebreak

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xenopus said:
snip...

Talking of UV lights, I just took my 5-year old caving (in Airman's Cave, Austin, TX) for 3 hours of crawling with an average 18 inch ceiling!). Had a great time, but didn't think to bring any ultraviolet flashlights. I don't know if limestone caves (either in general, or this one) are indicitive for growth of things that fluoresce, but it would have been interesting to see. Maybe next time. There were a number of slimy salamanders which really made his day, though!

http://www.xenopuselectronix.com/Caving/Airmans/05_21_06_1207.jpg

Piers

What an excellent adventure. Heh heh. That's one happy caver.:grin2:
 

GCalifornianus

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Most UV consumer lights are probably Class 1M, which is supposed to be safe to the eye "under all reasonably forseeable conditions of operation, provided they are not viewed with magnifying optics of any kind." That quote is taken from an article by Thomas Sovino in the October, 2003 issue of Conformity that I found doing a Google search one time.

http://www.conformity.com/0310optical.pdf

Mine's 375 nm and says it's class 1M explicitly. One time when I used it I did experience some grainy sand-in-the-eyes symptoms, which would be consistent with mild UV over-exposure, but it could also have been almost anything else (dryness from wind and low humidity, contact wear, tiredness, etc). I normally wear thasses with UV-blocking lenses, and when I'm using the light for a long period of time I don goggles that have more protection on the sides. It's probably overly cautious, but UV-blocking safety glasses are much less than $10 at a big-box home improvement store, so over-cautiousness at least doesn't cost much.
 

Canuke

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xenopus said:
We have found that clear safety glasses with "UV Blocking" stickers on them do not provide protection from most of our flashlights at 380nm and above.

This jibes with the results I've seen from my regular polycarbonate eyeglasses -- the Inova X5 UV at 390-400nm shines through them almost without attenuation, but the 365nm from my CFL blacklight stops dead at the lenses... not only do fluorescing things go dark in their shadow, but the "glare"-like effect caused by the fluorescing cornea/lens of my eyes goes away too.
 

David_Campen

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We have found that clear safety glasses with "UV Blocking" stickers on them do not provide protection from most of our flashlights at 380nm and above.
380 nm and above is hardly UV, more like plain violet, you hardly need protection from this.
 

Leef

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Hmmm. I don't know the wavelength of my LED. I bought the assembled light from the SS. Maybe their site shows -- I'll look.
 

David_Campen

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I posted this to my site, but I think it pertains to the discussion in this thread.

Damaged high-intensity light hurts sports-banquet attendees

Granted this was a ceiling-mounted HID and not a LED-based UV light, but it still demonstrates the serious nature of UV radiation.
The UV in the case mentioned above was short wave UV, probably 254 nm. The UV from LEDs is very long wave UV probably around 375-400 nm. These are very different things. Short wave UV photons contain enough energy to break chemical bonds, long wave UV photons do not.
 
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