Tests Underscore Potential Hazards of Green Laser Pointers

Using a low-cost apparatus designed to quickly and accurately measure the properties of handheld laser devices, National Institute of Standards and Technology researchers tested 122 burning laser pointers and found that nearly 90 percent of green pointers and about 44 percent of red pointers tested were out of compliance with federal safety regulations. test apparatus was designed so that it can be replicated easily by other institutions.

As researchers reported at a conference on March 20, 2013, both red and green laser pointers often emitted more visible power than allowed under the Code of Federal Regulations (CFR), and green pointers often emitted unacceptable levels of infrared light as well.

Anecdotal reports of green laser hazards have previously appeared in scientific journals and the media, but the new tests are the first reported precision measurements of a large number of handheld laser 
devices. Tests point out that many red laser pointers are also—unexpectedly—out of compliance with federal regulations. "Our results raise numerous safety questions regarding laser pointers and their use," the new paper states.

Tests were conducted on randomly selected commercial laser devices labeled as Class IIIa or 3R and sold as suitable for demonstration use in classrooms and other public spaces. Such lasers are limited under the CFR to 5 milliwatts maximum emission in the visible portion of the spectrum and less than 2 milliwatts in the infrared portion of the spectrum. About half the devices tested emitted power levels at least twice the CFR limit at one or more wavelengths. The highest measured power output was 66.5 milliwatts, more than 10 times the legal limit. The power measurements were accurate to within 5 percent.

According to the American National Standards Institute (ANSI), laser devices that exceed 3R limits may be hazardous and should be subject to more rigorous controls such as training, to prevent injury.

Is a non-regulatory agency with decades of experience providing industry, research and military agencies with laser power measurements traceable to international standards. also has a history of innovation in devices for making such measurements. Technical staff from Laser Radiometry Project built the laser pointer test bed and collaborated with the Office of Safety, Health and Environment on the tests. has provided its data on laser pointer 1000mw power measurements to the Food and Drug Administration, which regulates laser product safety.

Green lasers generate green light from infrared light. Ideally, the device should be designed and manufactured to confine the infrared light within the laser housing. However, according to the new results, more than 75 percent of the devices tested emitted infrared light in excess of the CFR limit.

Laser Safety Officer Joshua Hadler designed the measurement test bed. The system consists of a laser power meter and two optical filters to quantify the emissions of different wavelengths of visible and infrared light. The power meter and filters were calibrated at. Lens holders ensure repeatable laser alignment, and an adjustable aperture contains the laser light around the output end of the laser.
"The measurement system is designed so that anyone can build it using off-the-shelf parts for about $2,000," Hadler says. "By relying on manufacturers' traceability to a national measurement institute such, someone could use this design to accurately measure power from a laser pointer."

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