Even at very low power, green laser pointers and green LASER Blox™ are significantly more visible than red lasers. That’s because a common green laser emits a monochromatic beam at 532nm, a wavelength that’s very close to 550nm—the wavelength to which the human eye is most sensitive. Put simply, it’s easier to see green light than red.
This fact, combined with lots of press about green lasers “bringing down airplanes,” makes “Are green lasers more dangerous than red lasers?” the most common safety question I hear about lasers in the classroom.
At the classroom-safe power of either a <1mW Class II laser or a <5mW Class IIIa laser, the short answer is no, green lasers are not more dangerous than red lasers. But there is a caveat, and it’s important.
Class II and Class IIIa lasers are considered safe because the eye’s reflexive look-away response time is approximately 0.25s. At <5mW, a laser beam’s energy density (W/cm2 or J/cm2) isn’t sufficient to cause biological damage, and the eye is protected. Once you exceed the 5mW limit, however, the blink reflex no longer offers protection.
Here’s where the caveat comes in. A 532nm green laser is produced by pumping an 808nm infrared (IR) beam through a crystal medium, which doubles its frequency to produce the green beam. At 808nm, an IR beam is not visible to the human eye—and is therefore not subject to the protection of the look-away reflex. So if the IR beam escapes the aperture, it’s capable of doing eye damage. A high quality IR filter prevents such an escape and renders the green laser safe.
Many inexpensive laser pointers do not have an IR filter and therefore can be dangerous. Always buy laser products from reputable companies who explicitly state their compliance with both the FDA and ANSI. All of LASER Classroom’s™ green laser products are equipped with high-quality IR filters to ensure the safety of you and your students.