A Class 4 laser beam can cause materials to smolder or burn, especially at close range. Keep the beam moving to avoid burning materials at close range. Dark materials which absorb heat, and lightweight materials such as paper and fabric, are most easily burned by visible laser beams.
Laser glasses or goggles should be used when working with Class IV lasers, especially at close range (within a few yards or meters). They should be selected to protect against the laser's power and wavelength.
The eyewear should not block out all of the laser's light. This is because it is necessary to see where the laser "dot" is, to safely work with the laser. Because the eyewear is blocking some or perhaps all of the laser's light (for example, a hazardous reflection) you still should use caution even when using laser protective eyewear.
As you are using the laser, any other persons in the area should also have the same type of laser protective eyewear as you.
1.Classe 1: Output power can not cause eye damage.
2.Classe 2: The output power is less than 1 mW. If exposed, natural reflex to blink and turn his head enough to protect from the risk of injury.
3.Classe 3A: The output power is less than 5 mW, which limits the power reaching the retina to 1 mW when the pupil is dilated at maximum (estimated opening 7 mm).Therefore, the accidental exposure to a laser class 3A should not be more dangerous than exposure to a class 2 laser.
4.Classe 3B: The output power is less than 500 mW, sufficient to cause eye injuries that are described from a capacity of 150 MW
5.Classe 4: The output power exceeds 500 mW. These High Powered Laser Pointer can cause eye and skin damage and even cause inflammation of the objects on which they are directed.