Green laser pointers may emit high levels of invisible and potentially dangerous infrared light, a new study says.

Researchers report that green laser pointers deliver light that is brighter to the eye than red lasers, but the infrared light emitted by some inexpensive models could damage the retina of the eye.

Charles Clark, PhD, of the National Institute of Standards and Technology (NIST), led a research team measuring the output of several green laser pointers. The researchers bought three low-cost green laser pointers that had been advertised to have a power output of 10 milliwatts.

Researchers say one of the units emitted dim green light, but delivered infrared levels of nearly 20 milliwatts.

That’s enough to cause damage to the retina before a person is even aware of the invisible light.

Tests using several other laser pointers found intense infrared emissions in some, but not all, units.

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