Laser cleaning doesn’t hurt your hands, it’s just a gimmick.
Talking about human injury without talking about power density/energy is a hooligan.
The laser cleaning machine made by the 100W pulsed laser will indeed directly hit the hand in the defocus range in a short time, and white cleaning lines will appear without hurting the hand (the power density at this time is actually not large, because the light spot after defocusing becomes larger, and the power per unit area becomes much lower).
But you will burn (energy buildup) if you keep him still. Note that this is just a burn, that is, the carbonization of biological tissue on the surface of the skin, similar to the effect of focused sunlight, and there will be no breakdown.
Due to the focusing effect of the focusing mirror in laser processing, the energy density at the focal point is extremely high. Even with a 100W laser cleaning machine, I dare not test the position of the focal point with my hands.
Once due to operation problems, a colleague’s finger was wiped by a long pulse of 300W*0.5S near the focus, and there was a black carbonized line on the finger, and the pain that followed was simply touching.
Therefore, whether the laser does harm to human tissue depends on the power density first. With a 1000W laser, if you stand a few meters away from the processing head (150mm focal length), your face or hands will just feel hot, like sunbathing.
If you focus on it, even objects like copper and aluminum that have an ultra-low absorption rate of 1064nm wavelength infrared lasers will have a molten pool, not to mention tender flesh.
The state has clear regulations on laser grades. The power starting point of the fourth-level laser is 0.5W laser power. Class 4 laser: Class 4 lasers are harmful to eyes and skin, and direct reflection, secondary reflection and diffuse reflection can cause damage. All Class 4 laser systems carry a “Danger” sign.
Class 4 lasers can also damage materials in or near the laser area, igniting flammable substances. It is recommended to wear eye protection when using this series of lasers.
Improper use, so that the eyes and skin are exposed to direct or scattered light beams, can damage the eyes and skin, and cause a fire. Example: Near-infrared fiber lasers for marking and cutting weld bars.
Therefore, all industrial products involving lasers should be used for safety protection. Operators must undergo professional training and understand the corresponding hazards before they can work.