Laser Safety Levels in Detail
According to the classification of laser hazards to human beings, the MPE (maximum possible effect) to the eye observed within the beam is used as a benchmark and can be categorized into Classes I to IV. Manufacturers of laser products should place Class II, III and IV warning labels on their laser products.Class I: Low output lasers (power less than 0.4mw) will not exceed the MPE value regardless of the conditions on the eyes and skin,
even after focusing through the optical system. This ensures that the design is safe and does not require special management. Typical applications include laser whips, CD players, CD-ROM devices, geological exploration equipment and laboratory analyzers, and short-distance communication transmissions. (Used with exposed light source)
Class II: low output visible laser (power 0.4mw-1mw), the reaction time of human closed eyes is 0.25 seconds, and the exposure calculated with this time can not exceed the MPE value. Usually, lasers below 1mw will cause dizziness and inability to think, with closed eyes to protect, can not be said to be completely safe, do not observe directly within the beam, and do not use Class II lasers to directly irradiate other people's eyes, and avoid observing Class II lasers with telescopic equipment. Typical applications are classroom presentations, laser whips, aiming devices and rangefinders.
Class III: Medium output lasers, whose beams can be harmful if directed into the eyes, are further categorized into Classes IIIA and IIIB for certain safety reasons.
III A is a continuous laser for visible light, the output is a laser beam of 1-5mw, the energy density of the beam should not exceed 25W/m-m, avoid using telescopic equipment to observe the IIIA laser, which may be dangerous.The typical applications of IIIA and Class II have a lot in common, such as laser whips, laser scanners, etc. Class III B is a laser beam with an output of 5-500mw, which can cause injury if directed into the eyes.
III B is a continuous laser of 5-500mW, which is dangerous to observe directly in the beam. However, the minimum irradiation distance is 13cm, and the maximum irradiation time is less than ten seconds, which is safe. Typical applications of Class IIIB lasers are spectral determination and entertainment light shows.
ClassIV: High output continuous lasers (greater than 500mW), higher than Class III, are a fire hazard and diffuse reflection is also hazardous. Typical applications are surgery, research, cutting, welding and micromachining.