Despite all the bad press about green laser pointers, including the numerous lawsuits against people shining them into airplane cockpits (http://www.laserfocusworld.com/articles/2011/03/house-criminalizes.html) and the recent news from NIST that 90% of the green laser pointers out there don't meet US federal regulations, I must admit I've always wanted to have one. And not just because my red laser pointer is a bit weak when it comes to illuminating presentation slides, but because green is a great color, very bright, state-of-the-art, and oh so great at making my dogs dance around trying to catch the beam!
On my recent visit to Shanghai, China for the 2013 Laser World of Photonics (http://www.laserfocusworld.com/blogs/photon-focus/2013/03/nlia-and-clusters-advance-china-s-domestic-laser-industry.html) conference (see my conference review at http://www.laserfocusworld.com/articles/2013/04/Laser-China-2013-review.html), I learned from a Laser Institute of America (LIA) colleague that there might be a guy walking around the exhibits flashing a green laser pointer for sale. "Don't pay more than 150 RMB, though" he cautioned, as the price typically starts out much higher and that was the typical price as of the 2012 conference. With 150 RMB (Chinese Yuan Renminbi) equating to around only $24 US dollars, I was ready to buy. Sadly, I didn't see the guy during the whole three-day conference.
So imagine my delight when, on the last afternoon of my visit where I was fortunate enough to be invited shopping at the Yuyuan Garden in Shanghai, that I came across a man flashing a multi-pointed, dazzling projection that could only be a green laser pointer! I wasn't quite sure what my colleague meant when he said that the pointers were typically equipped with an optic at the front that produced a sort of kaleidoscope image -- but now I knew what he meant (see photo below).
The "salesman" demonstrated the power of the pointer by shining it on a building almost 200 feet away. I was hooked. And when he said 150 RMB as the first price, I nearly said OK. But then the haggler in me (living so close to Mexico) decided to bargain. The end result, 120 RMB or two for 100 RMB each (way less expensive than the fake Rolex I bought in a dark hallway later that day--but that's another story). Fortunately, one of my shopping companions jumped in to buy one at 100 RMB, so I got my pointer!
Now if I were better prepared for my trip to China, I would have checked in advance what green laser pointers cost, but I figured I couldn't go wrong at less than $20. But when I returned home, I decided to check prices. On Amazon.com, I was surprised to find out that most of the pointers were 5 mW at less than $10, with 50 mW pointers at about $40, and even more powerful "stargazing" pointers for up to $80 (although power levels weren't pointed out). I even found a Laserglow Technologies 20-225 mW pointer starting at $229 on a simple web search.
So just how powerful was my pointer, was it a good buy, and was it safe (as if I cared)? I checked out the safety label on the pointer (http://www.laserfocusworld.com/articles/print/volume-48/issue-04/features/retinal-injury-research-impacts-future-laser-safety-standards.html) and the words "DANG ER" should have been my first clue regarding safety. Not "DANGER", but "DANG ER" with a space between DANG and ER--an obvious printing error on the poorly applied label.
The label revealed that my Class III 532 nm +/- 10 nm laser pointer had a power rating of < 200 mW. It even says it complies with 21 CFR. Perhaps NIST could check it for me and find out just how powerful it really is?
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