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ArcticMyst Security by Avery

Cheap ebay 532nm laser pen IR leakage

Joined
Nov 1, 2013
Messages
43
Points
8
I have read numerous posts about the cheap laser pens and IR leakage. I bought a couple of the "sets of three" for about 15 bucks from a couple of sellers.

I have an Ophir head that I've connected to a voltage display panel and can get a good idea of output using it. It's not an official LPM yet though. I need a couple more things and then it needs an enclosure.

Also, my other hobby is astronomy. Some of the paraphernalia I've picked up includes an IR cutoff filter for CCD imaging.

I was sitting here and the idea hit me. Why not put the green lasers behind the IR filter and see how much the power drops. Great idea, huh? :)

Well, the first pen measures 30mW to 33mW on the meter. I put the filter on the beam and the output drops to 24mW to 26Mw. Not too bad.

The next one is a solid 40mW on the meter unfiltered. When I put the filter in the path, the power drops to 4mW to 6mW. Yes, that is correct, the filter blocks 32mW to 36mW of power. I did it a couple of times to make sure I wasn't messing something up.

I was amazed. Unfortunately, I do not have pics. I will add some later when I get the meter completed and some clamps/stands for the lasers. At the moment I am holding both the laser and the filter and I don't have an extra hand for the camera.

Anyway, I wonder if my experience is common? Is 90% IR the general rule with these or do I have a "rare" specimen?

-Bob
 





Joined
Jul 4, 2012
Messages
2,834
Points
63
Whoa- that is a crazy big ratio of visible:IR. I have never heard of nor seen and ebay pens that are that bad- my guess is just crappily aligned crystals inside.
 
Joined
Feb 21, 2013
Messages
5,013
Points
0
Not that uncommon. Most of those lasers get the power from IR. Had two lazerer sticks that had 10-15mW of IR each and I was happy with those. I think my LaserBtb has 0mW IR but I havent tested it since i got my IR filter. My filter blocks all visible light and only lets IR through so its similar to yours just opposite from what im getting ;)
 
Joined
Aug 7, 2010
Messages
2,086
Points
0
Get an IR filter, glue it inside, and you will have a real <5mW green laser pen, which is hard to find for cheap.
 




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