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Laser Classifications and Laser Welding Dynamics

Classification Chart

Lasers are classified by the measurement of their power out-up, with a rating ranging from 1 to 4; 1 being the lowest and least hazardous, and 4 being the highest and most dangerous.

Laser Classifications

Classification #1

This category covers all lasers in the lowest power range, which represent no immediate hazard.

Classification #2

This category covers low powered lasers that may emit a visible beam, but do not pose an immediate hazard for superficial burns to the skin, or damage to the eye, unless exposed for a prolonged period of time. Lasers in this category, in terms of hazards, could be compared to your average electric light, i.e. if you were to look directly at a light such as a typical 60 watt light bulb, or hold your arm too close to a light bulb for an extended period of time, damage to your eyes, or burns to your skin will result.

Classification #3A

This class of laser may cause immediate eye damage in the event of a direct exposure, and should be operated with care. Skin damage is unlikely unless subject to prolonged exposure, and this class of laser is generally not considered hazardous.

Classification #3B

This class of laser may cause immediate eye damage in the event of a direct view or a reflected view. Skin damage is not likely unless subject to prolonged exposure, and is only considered slightly more hazardous than lasers in the 3A classification.

Classification #4

This category refers to all lasers in the highest power range. Lasers in this class have the potential to cause eye damage, via direct and reflected views, and skin damage immediately upon exposure. Laser in this class are also considered a fire hazard, i.e. they can ignite any flammable materials they come in contact with.

Laser Welding Dynamics

The power, performance and output of laser welding equipment are measured using the following dynamic components:

Laser Energy

Peak laser energy is measure in watt/seconds or joules. Average laser energy is simply measured in watts.


Measured in hertz, frequency refers to the rate the laser pulse or blast repeats in a given time period.


A laser beam can be focused onto a specific spot that’s no more than a thousands of an inch—literally the size of pinpoint.



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