Class 3R (IIIa) laser safety information

Class 3R lasers are considered safe when handled carefully. There is only a small hazard potential for accidental exposure. For visible-light lasers, Class 3R lasers' output power is between 1 and 4.99 milliwatts.

In the United States, both Class 2 and 3R lasers can be sold as "pointers" or for pointing purposes. (In Australia, the U.K., and many other countries, laser pointers are restricted to Class 2 only.)

Class 3R is essentially the same as the Roman numeral "Class IIIa" you may see on some lasers' labels. At this website, we primarily use the Arabic numerals, for convenience.
A Class 3R laser is low powered. It normally would not harm eyes during a momentary exposure of less than ¼ second. This is within the aversion response, where a person turns away and/or blinks to avoid bright light.

Do not deliberately look or stare into the laser beam. Laser protective eyewear is normally not necessary. A Class 3R laser is not a skin or materials burn hazard.

However, a Class 3R 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 unsafe and is illegal -- you could be arrested and jailed.
This is not a toy. Children can safely use Class 3R lasers only with continuous adult supervision.
SAFETY NOTICE: This website is intended for the educational, instructional and informational purposes of the user and is not to be considered a substitute for a knowledgeable and trained Laser Safety Officer (LSO) with the duties and responsibilities as defined in the ANSI Z136 standard published by the American National Standard Institute.

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.

Always err on the side of safety. If your laser has not been measured by a knowledgeable and trained Laser Safety Officer, assume it is more hazardous than the label or marketing materials would indicate.
Class 3R 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 look into or 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 3R visible-beam laser (4.99 mW) with a tight beam (0.5 milliradian divergence) is 104 ft (32 m).

Color indicates the relative hazard: Red = potential injury, green = unlikely injury. Beyond the Nominal Ocular Hazard Distance, the chance of injury is “vanishingly small” according to safety experts.

For a 4.99 mW Class 3R laser with a less-tight beam that spreads out faster (1 milliradian), the NOHD is 52 feet (16 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 longer than about ¼ second. The closer you are to the laser and the longer the beam is in the eye, the greater the chance of injury.
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. This is why aiming any laser towards an aircraft is illegal.
  • A 4.99 mW Class 3R laser beam can temporarily flashblind a pilot or driver, causing afterimages, within 530 ft (160 m) of the laser.
  • It can cause glare, blocking a pilot or driver's vision, within 2400 ft (730 m) of the laser.
  • It can cause distraction, being brighter than surrounding lights, within 4.5 miles (7.3 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 3R consumer laser.
  • The more the beam spreads out, the shorter the hazard distances. For example, for a 4.99 mW 555 nm green laser pointer 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.
Visual interference distances for other Class 3R lasers are listed in the Laser hazard distance chart.

Never aim a laser at or near aircraft or vehicles, no matter what its color or power.
In the U.S., aiming a laser at or near the flight path of an aircraft is a federal felony, punishable by up to 5 years in jail and a fine of up to $250,000. Other countries, and U.S. states have similar laws for interfering with safety; such laws may be used to arrest, fine or imprison a person for aiming at aircraft and vehicles.

The power of the laser does not matter. Even if a laser's power is relatively weak, aiming ANY laser beam at an aircraft or vehicle is illegal.

Persons aiming higher-powered beams are especially likely to be caught, because the beam is very visible from the air. It is easy for police helicopters to trace the beam back to the perpetrator's location.

See this page for a selected list of the many persons who have been jailed and/or fined for aiming lasers at aircraft.
  • General information about laser hazards and classes (Classes 1, 1M, 2, 2M, 3R, 3B and 4)
  • A page with additional links and resources on consumer laser safety, what to do if you are injured, lasers and aviation safety, a laser pointer safety website, and laser industry groups.