In the past few years we’ve seen an increase in injuries coming from laser pointers. They sometimes involve severe retinal damage and irreversible blindness. These injuries usually come from misleading or improperly-classified lasers that are openly available on the market.
This is an urgent matter: more than 7 cases of people under 18 years old who now have to live with permanent reduced vision (read more about these 7 cases), all in the past 4 years only! The dangers of laser pointers are real and the situation is not improving.
If we go back in time, we could see a few red laser pointers that were used in classes, but these were generally safe. However, I still remember the first teacher that brought up a green laser pointer in class for the novelty effect.
These first laser pointers were meant to be used at night for astronomy. The difference between red and green laser is that you can see the beam at night. They weren’t meant to be used by everyone, and the price was quite high.
Now that manufacturers can purchase low-cost laser diodes from dubious origins, we see them overflowing the market.
How dangerous are laser pointers to human eyes?
If you want to know how dangerous laser pointers can be, take a look at this rave that took place in 2009 near Moscow where at least 12 partygoers were affected by cases of laser blindness because the lasers were mislabelled.
More recently, at least 111 cases were documented of people who got their vision impaired following a laser exposition.
But from these 111 cases, what worried me the most about them was that children were among those affected. We, as a society, need to be informed about the risk from the unrestricted access of these high-performance lasers you can buy on internet.
Lasers, depending on wavelength, power, exposure time, spot size and localization, can make permanent damage to eye and retina, which can lead to blindness. The retina is the part of the eye that is considerably at risk because a laser goes through the transparent crystalline part of the eye and burns the nerve-covered part of the retina.
This area cannot self-regenerate. Usually, the blink reflex or eye-rolling are protective mechanisms protect the eye against laser less than 1 mW. This class of laser can only cause injuries if the exposure time is longer than 0.25 seconds. This is the typical time it takes for you to blink. However, it’s not only ravers or children that will react this quickly, but most people actually.
The good part is that the pupil is not very big and we can usually avoid it, but it doesn’t mean that it’s still safe.
Even if we regulate and test laser pointers to insure they remain under 1 mW, most devices you can purchase from direct resellers who sell them with the best of their knowledge are mistakenly identified as safe, but they do pose a risk.
These laser pointers are usually battery-powered and are more dangerous in the blue or green wavelengths as the output is never precisely the one specified in their documentation.
To achieve different colors, they use a frequency doubler, which means they do not only emit in the color you see but also in the infrared spectrum. This implies they deliver a much higher power than expected, or even specified.
Also, the specs provided are determined at a specific temperature. This means it is possible to have different and unexpected results with the same laser when it is used in different conditions, such as outdoors, in hot environments, etc.
The best way to be sure is to measure the output with a Gentec-EO photodiode laser power meter.
And if you look at the sample from the kid’s injury, what we can see is that the average green laser power they were exposed is at least 45 mW. It’s very wrong to let anyone without proper laser safety training manipulate this. All these lasers could be one purchased with specs under 1mW for what I’ve seen and purchased.
Laser pointer power experiment
To satisfy my personal curiosity I purchased a handheld blue laser pointer from a popular website. It was stated that it would emit 400 mW. I got this for 50 dollars and I tested it with the above Pronto-Si: it delivered less than 400 mW but a whopping 323 mW that could engrave any material at its focal point measured of 110 µm measured with a Beamage-3.0. This is even more dangerous than a 1 kW laser: why? Because it’s not locked in a safe room that only training staff can access.
This is not a toy and it’s not locked. Are people aware about the dangers of laser pointers like these?
I’m not even talking of those who wants to wilfully miss use the laser to attack in a crowd or point a plane in flight such as this kid who pointed his pointer to a CF-18. Transport Canada got 600 similar events listed.
To wrap this up, until we can test all the lasers that are available, please do not trust the output specified unless you tested it with a laser power meter.