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WHAT IS A CLASS 2 LASER?
Class 2 lasers are considered safe for normal operation. Class 2 lasers' output power is below 1 milliwatt. All class 2 laser pointer emit visible light only. Class 2 is the same as the Roman numeral "Class II" you may see on some lasers' labels.
A Class ii laser is relatively weak. It normally would not harm an eye unless a person deliberately stared into the beam. Laser protective eyewear is normally not necessary. A Class II laser is not a skin or materials burn hazard. However, even a Class 2 laser can be a distraction, glare or flashblindness hazard for pilots and drivers. NEVER aim any laser towards an aircraft or vehicle that is in motion.
SAFE USE GUIDANCE - GENERAL
A Class 2 laser is relatively weak. It normally would not harm an eye unless a person deliberately stared into the beam. Laser protective eyewear is normally not necessary. A Class II laser is not a skin or materials burn hazard. However, even a Class 2 laser can be a distraction, glare or flashblindness hazard for pilots and drivers. NEVER aim any laser towards an aircraft or vehicle that is in motion. This is not a toy. Children can safely use Class 2 lasers only with continuous adult supervision.
CLASS II LASER HAZARDS
The hazard distances listed below are intended only as general guidance. This is because 1) your laser may vary from the parameters (power, divergence) listed below, and 2) information on labels or marketing materials may not always be correct. For example, studies have shown that some laser pointers may be falsely labeled to avoid regulations -- the actual power may be 10 times or more what the label indicates.
EYE INJURY HAZARD
Class 2 visible-light lasers are considered safe for unintentional eye exposure, because a person will normally turn away or blink to avoid the bright light. Do NOT deliberately stare into the beam -- this can cause injury to the retina in the back of the eye.
Be aware of beam reflections off glass and shiny surfaces. Depending on the surface, the reflected beam could be about as strong and as focused as a direct beam.
The Nominal Ocular Hazard Distance (NOHD) for the most powerful Class 2 laser (0.99 mW) with a tight beam (0.5 milliradian divergence) is 46 ft (14 m).
For a 0.99 mW Class 2 laser with a less-tight beam that spreads out faster (1 milliradian), the NOHD is 23 feet (7 m). This divergence is more typical of consumer lasers.
If you are closer than the NOHD distance to the laser, there is a possibility of retinal damage if the direct or reflected beam enters your eye for longer than about ? second. The closer you are to the laser and the longer the beam is in the eye, the greater the chance of injury.
AIRCRAFT AND VEHICLE SAFETY
NEVER aim any laser towards an aircraft or vehicle that is in motion. The bright light can flashblind, cause glare, or distract the pilot or driver.
A 0.99 mW Class 2 laser beam can temporarily flashblind a pilot or driver, causing afterimages, within 240 ft (73 m) of the laser.
It can cause glare, blocking a pilot or driver's vision, within 1050 ft (320 m) of the laser.
It can cause distraction, being brighter than surrounding lights, within 2 miles (3.2 km) of the laser. The above calculations are for a 555 nanometer green laser pointer with a tight beam (0.5 milliradian divergence). These parameters are very conservative and thus result in the longest visual interference distances for a Class ii consumer laser.
The more the beam spreads out, the shorter the hazard distances. For example, for a 0.99 mW 555 nm green laser pointers with a beam spread of 1 milliradian, divide the above numbers by 2 to find the visual interference distances.
Green is the most visible color to the human eye. It will appear brighter and more distracting than other colors of equal power. For red, divide the above numbers by about 5 to get an approximation of the visual interference distances. For blue, divide the above numbers by about 20.