Class 1 lasers have an output power that is below the level at which eye injury can occur.
Class 2 lasers emit visible light and are limited to a maximum output power of 1-milliwatt (mW). A person receiving an eye exposure from a Class 2 laser will be protected from injury by their natural blink reflex, an involuntary response which causes the person to blink and turn their head, thereby avoiding eye exposure.
Class 3A lasers may have a maximum output power of 5 mW. This limit restricts the power entering a fully dilated human eye (taken as a 7 mm aperture) to 1 mW. Thus, accidental exposure to a Class 3A laser should be no more hazardous than exposure to a Class 2 laser. However, Class 3A laser pointers are hazardous when viewed with an optical aid such as binoculars and are therefore not suitable for the general consumer.
Class 3B lasers have an output power up to 500 mW, sufficient to cause eye injury. The extent and severity of any eye injury will depend upon several factors including the laser power entering the eye and the duration of the exposure. Class 1, Class 2,
Class 3A and Class 3B lasers do not have sufficient power to cause a skin injury.