Testing for IR filter?

[acritzer]

Ended up with an e-bay 30mW laser from as a groomsman gift. I've done a bit of reading and probably know that there isn't an IR (hoping there is though) filter on this thing, but of course the seller claims there is.
I think it was from HDE (Hottest Deals Ever).

Wondering if there is an easy way to test for the filter? I've read things about using cola as a filter for the green and viewing with a DV on night mode. Tried that but there was still visable green through the cola. What about using color filters that come with TV calibration discs? Red, Green, Blue?

Follow-up, assuming there isn't already a filter in place, how difficult/advisable is it to add one? Obviosly I have no experience taking these things apart.

Thanks.

 

[GooeyGus]

Dont worry about it. the IR poses virtually no safety risk when compared to the green coming out. Worry about the green, not the IR, and you'll be fine.

 

[acritzer]

Why are there so many people that caution against the IR? Even the FAQ on this forum say it's pretty dangerous.

 

[dr-ebert]

The IR output may be dozens of times greater than the green light output, so from close up, it can be enough to damage your eyes. Since it's invisible, there is no warning for you. However, the IR generally isn't as well collimated as the green, so it doesn't stay in a thin beam but spreads. On one hand, that's good, as it will be harmless after a couple of meters or so. On the other hand, this may mean that IR is hitting your eye when you think you're aiming the laser past your head.

One good way to check for spreading IR should be this: take a piece of cardboard and cut a small (5mm dia) hole into it. Aim the laserbeam through the hole from a few meters away, then check with your DV in night mode whether there's a bright halo around the hole that isn't there in visible light.

If you stay out of the visible beam, AND don't look at the aperture from close up while the laser is running either, you should be safe from IR.

 

[acritzer]

Thanks, I'll give that a try. Any advice on installing a filter myself? Is it hard to do? Is it worth it? Any reasonable way to open up the laser without hacking it up?

 

[GooeyGus]

again, dont worry about it. Optically, the 808 and 1064nm light basically has to go through walls to get out. The only IR you'll get out the end is Ir that has reflected against the inside of the case and then made it out, and a tiny tiny bit that makes it through the reflective coating on the crystals. I would be really really really surprised if you even get 5mW of IR coming out the end.

Infrared lasers are very dangerous on their own. If you have collimated 1W 808nm laser then it is a very dangerous thing, because all your light is invisible and the laser is designed to get all of it out the end of the laser in the most efficient way possible. In a green laser, the green light will be many times more powerful than any infrared light that makes it out the end.

The whole reason people were worried about IR leakage to begin with is because people wanted accurate power measurements of their lasers, to find out exactly how much green you are getting. If you have IR leaking out, that will effect the power reading so you wont really know how much green you really have. Somewhere along the need for an IR filter for accurate power measurement turned into some crazy paranoid safety issue. YES IR laser light is dangerous, as is ALL laser light. But in the case of a green pointer, dont worry about the IR coming out, the green will do damage to your eyes WAAAAAY before the IR ever will.

 

[DrSined]

One says no, other says yes.... So I ask directly! I plan to buy the 532nm laser with 5000 mW:
http://i.imgsafe.org/1a6086e.png

So IR is needed or not???

Thank you.

 

[diachi]

One says no, other says yes.... So I ask directly! I plan to buy the 532nm laser with 5000 mW:
http://i.imgsafe.org/1a6086e.png

So IR is needed or not???

Thank you.

This thread was last updated in 2009 - you should avoid bringing back such old posts.

You should ask the manufacturer to be sure - you'll be spending big money on that thing. That said, no, you shouldn't need to add one, that laser should have one built in. Wether it's a result of the cavity design or perhaps it has an IR filter external to the cavity, either way it's hard to say without seeing the insides which it is. Wouldn't worry about IR from that though.

What are you planning on using 5W of 532nm for anyway? That's a stupidly bright laser.

Edit: You could have asked this in your other thread.

 

[Pi R Squared]

One says no, other says yes.... So I ask directly! I plan to buy the 532nm laser with 5000 mW:
http://i.imgsafe.org/1a6086e.png

So IR is needed or not???

Thank you.

Yes an expensive high quality and very powerful lab laser like that should always have an IR filter, I expect it does.

The 30mW mentioned above is no big deal.

Alan

 

[DrSined]

This thread was last updated in 2009 - you should avoid bringing back such old posts.

You should ask the manufacturer to be sure - you'll be spending big money on that thing. That said, no, you shouldn't need to add one, that laser should have one built in. Wether it's a result of the cavity design or perhaps it has an IR filter external to the cavity, either way it's hard to say without seeing the insides which it is. Wouldn't worry about IR from that though.

What are you planning on using 5W of 532nm for anyway? That's a stupidly bright laser.

Edit: You could have asked this in your other thread.

I just want it for outdoor parties to mark the venue, the laser will be directed into the distance! that's why I want to make beam visible over long distances And then for fun of course!

I have read already dozens of threads here about IR and still I have not found convincing answers!
In my opinion, for such a huge power of 532nm light is IR filter needed, because output power of IR will be also very high and it is dangerous and risky if you cant see it. Or you think it is safe? Unless flash up directly into the eyes or if you are going to look into the opening of the laser from a short distance?
I had read here that divergence of IR can be very high and may hit and damage eyesight even if you just look at beam from the side.. Is that true?

 

[Laser Chick]

It is true that IR flares to the sides of the green beam but you would still have to be dangerously close to the beam for a direct shot to the eyes.
Reflective issues are mode likely if you point the green beam to just pass a surface as the IR could be reflecting off of that surface.

Dang, you really dragged this thread out of the dusty back corner of the closet!!