Are Lasers Dangerous?
Whether or not a laser is dangerous depends upon its output power. Very low power lasers are safe. Moderate to high power lasers can be hazardous to the eyes and, in some cases, the skin.
Countries such as the U.S.A., where many diode laser pointers come from, have laser safety standards with mandatory classification and labeling requirements. In this system, all lasers are classified into one of four classes. The classification number (one to four) and appropriate warning statements must be labeled on the device.
Class 1
This laser does not present a hazard.
Class 2
This laser also does not present a health hazard provided one does not focus the beam directly into one's eyes.
Class 3
These lasers fall into one of two sub-classes: 3a and 3b.
Class 3a
Slightly more powerful than class 2 lasers and one should not focus the laser beam in anyone's eyes. Class 3a lasers, when viewed through a magnifying lens, have the ability to cause harm.
Class 3b
These lasers are dangerous and can damage to one's eyes instantaneously upon exposure. They require a longer exposure time to burn skin.
Class 4
The last class of lasers are dangerous and can damage eyes and skin instantaneously upon exposure. Some can damage eyes even from a diffuse reflection. Class 4 lasers can cause materials to ignite.