14 DAY TRIAL // Even the most inexpensive green lasers may be more harmful to the eyes and one's health than initially calculated, say experts who looked at how much infrared light the devices emit.
Generally, a ball point pen-sized green laser device can be bought from anywhere in the United States for about $15.
Manufacturers say that the standard output power for these devices is 10 mW, and that they don't emit too much dangerous infrared radiation.
This was recently proven to be false, in a study conducted by experts at the US National Institutes of Standards and Technology (NIST), who looked into several types of commercially-available green lasers.
Working together with colleagues from the University of Maryland, the experts determined that some of the handheld lasers they investigated emitted as much as 10 times more infrared wavelengths than green light.
These tools generally have a simple operating principle. First, light is produced at a wavelength of 880 nanometers via a standard diode.
Secondly, the photon beams are passed through a neodymium magnet, which changes their wavelength to 1064 nanometers. The third step is using a frequency doubling crystal to modify the wavelength of the beam to 532 nanometers (green light).
The research team, which was led by expert Jemellie Galang, shows in the new work that most green lasers that can be found on the market today have higher-than-advertised infrared light outputs.
“This is a serious hazard, since humans or animals may incur significant eye damage by exposure to invisible light before they become aware of it,” Galang says.
“We have found that this problem is common in low-cost green laser pointers, though its seriousness varies widely,” the expert adds further.
In one of the devices that were investigated, researchers found no IR filter, nor any slot for such a filter.
The experts say that this was most likely a design decision on the part of the company that manufactured the device, and that it was most likely taken to reduce production costs.
The fact remains that green lasers can be very dangerous, and people should take at least some basic precautions when operating them, Technology Review reports. Follow me on Twitter @TudorVieru