# Laser pointers and UV



## gcbryan (Oct 16, 2011)

I've always heard that cheaper laser pointers aren't shielded for UV and that is sometimes used as a reason for one to buy a more expensive laser pointer.

I have two inexpensive laser points both are only 5mw however. I have a red and a green pointer.

I also have some material that is extremely sensitive to UV. They are white plastic beads that change color while outside or inside only under a UV source. I shined both of my lasers at this material and it stayed white. I have a small UV keychain light and when I shine it at the beads they turn bright deep colors almost immediately.

Now this is hardly a scientific test and specifically it only applies to my two laser pointers but I found it interesting and it may indicate that even cheap pointers may not emit the UV that we've been lead to believe that they do.


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## Harold_B (Oct 16, 2011)

I think you might be mistaken. Early red lasers were around the 670-680nM range with a little bit of near IR output, not UV. The lower the wavelength like the green the less IR content there will be. The closest you will get to UV in a visible laser will the 405nM blue lasers used in disc players.

Perhaps your reference was thinking about blue lasers or even UV down converted LEDs?


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## FRITZHID (Oct 17, 2011)

gcbryan said:


> I've always heard that cheaper laser pointers aren't shielded for UV and that is sometimes used as a reason for one to buy a more expensive laser pointer.



actually, the worry in cheap lasers, especially high powered ones, are the green DPSS lasers, they use an Hi power IR laser diode to create the green beam using freq altering xtals, many of the cheap versions of these lasers do NOT have IR filters on the ends (not so much to reduce cost, but when tested with a mW meter, the IR will add to the total power) and this lack of filter can cause alot of harm to the eyes, even in a reflected beam. PLEASE be Cautious when using high power lasers in general, but especially the cheapies.


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## bshanahan14rulz (Oct 17, 2011)

You can search for laser IR filter, there are a few shops that sell little square filters just the perfect size for gluing in the inside of the aperture of your green laser (using 2 part epoxy, NOT superglue or any other out-gassing adhesive).


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## Bigmac_79 (Oct 17, 2011)

Like has been said, the worry is not the ultraviolet, but the infrared. And the problem is that the infrared beam tends to be wider (sometimes much wider) than the visible beam of the laser. Your eyes won't see the IR, but they can be damaged by it if it is powerful enough. So, while you may think you are being careful to not get the beam in your eyes (or your friends eyes), the IR could be damaging you and you wouldn't realize it.

I good test to get a look at the IR in your laser is to look at the dot through some sort of digital camera or webcam or phone camera. Most of these have some sort of IR filter, but will still pick up some IR (much more than your eyes). To test to see if your camera can see IR, point your TV remote at it and press some buttons.


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## xxcat (Oct 19, 2011)

635nm diode laser would not emit UV light. And for green laser, infrared laser light is much danger. If the cheap pointer don't have the IR filter, it would emit 1064nm infrared laser ligth


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## gcbryan (Oct 21, 2011)

I was mistaken regarding the UV danger. I guess it was IR danger that I was thinking of. I do have a digital camera that can detect some IR. I can see the IR emitted from my TV remote control. My green laser (and red for that matter) is 5mw. How likely is that to cause damage from IR (assuming I'm not looking into the laser of course)?

Using the digital camera it's hard to locate IR since it's hard to separate from the green light itself.


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## bshanahan14rulz (Oct 21, 2011)

Probably not feasible, but if you shined the laser through that black-looking plastic window that remotes used to have, the IR will probably leak out. Just, most people don't want to ruin one of their remotes for this.

You could punch a hole exactly the size of the green dot and you'd see some of the IR that doesn't go through the hole.

with a 5mW, IR shouldn't be that much of an issue really. Might be around 50mW or so. Also, it diverges more quickly than the green. at about a foot or so, if your green dot is o, the IR will be O.

If I can find it, I'll post where I saw some IR filters that were already cut down for use in pointers. I can't remember right now where it was...


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## Antony R (Nov 18, 2011)

Make the right selection on UV laser source to point your required distance.... The specific criteria on the lasers could make the difference.... So select your regarding need from perfect electronic shops...!


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## reehasmith (Nov 21, 2011)

I agree with you that a main problem we are facing is just because of cheap laser pointers. thanks for sharing.


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## jspeybro (Nov 21, 2011)

bshanahan14rulz said:


> Probably not feasible, but if you shined the laser through that black-looking plastic window that remotes used to have, the IR will probably leak out. Just, most people don't want to ruin one of their remotes for this.


perspex black 962 is available for cheap and perfect for this test! that's one of the materials used in remotes ;-)


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