Warningssign

Laser classes and safety

Description of the new, international laser classes

Class 1

A Class 1 laser is not dangerous even under a longer (100 seconds) exposure time. Either is the laser so week that there is no risk for injuries or is the laser with high output power sealed in a way that radiation is prevented.

Class 1M (magnifyer)

A Class 1M laser is safe with the conditions that the laser beam is not focused but diffused. In this way the exposure time for a human eye cannot be exceeded. The total output power or the pulsed energy can exceed the permitted values under Class 1 (valid for UV, visible and IR). If the beam is refocused the laser class will be changed and the laser can become dangerous.

Class 2

Class 2 laser is safe because the human eye’s blink reflex will reduce the exposure time to 0.25 seconds. This class includes lasers with visible wavelength (between 400 and 700nm). The output power of the laser must not exceed 1mW.

Class 2M (magnifyer)

A Class 2M laser is safe because the human eye’s blink reflex will reduce the exposure time to 0.25 seconds. This class includes lasers with visible wavelength (between 400 and 700nm). A Class 2M laser correspond a Class 2 laser but in this class the laser beam is diffused (e.g. a line laser). If viewed with magnifier or other optical instrument the laser class will be changed and the laser can become dangerous.

Class 3R (restricted)

A Class 3R laser is divided into two groups, visible and invisible (e.g. UV or IR) light. Visible light (wavelength between 400 and 700nm): Class 3R includes lasers with higher than 1mW but lower than 5mW output power. Invisible light: Higher output power than for Class 1 or 5 times the Maximum Exposure Time for a Class 1 laser. A Class 3R laser exceeds the maximum exposure permitted and can potentially cause eye injuries.

Class 3B

A Class 3B laser is divided in two groups, visible and invisible (e.g. UV or IR) light. Visible light (wavelength between 400 and 700nm): Class 3B includes lasers with an output power higher than 5mW but lower than 500mW. Invisible light: 5 times the Maximum Exposure Time for a Class 1 laser but with an output power lower than 500mW. Class 3B lasers may have sufficient power to cause an eye injury, both from the direct beam and from reflections.

Class 4

Class 4 lasers have an output power higher than 500mW.

Class 4 lasers are always dangerous for both the human eye and for the skin. Warning! Even diffuse reflexes can be hazardous under some circumstances. This class has no upper limit.