Cheap ebay 532nm laser pen IR leakage

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

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.

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

Get an IR filter, glue it inside, and you will have a real <5mW green laser pen, which is hard to find for cheap.