Green Beam Laser Pointer Pen

Laser produce a narrow beam of light in which all of the light waves have very similar wavelengths. The laser's light waves travel together with their peaks all lined up, or in phase. This is why laser beams are very narrow, very bright, and can be focused into a very tiny spot.
As a high-tech alternative to the retractable, metal pointer, the laser pointer beam will produce a small dot of light on a target. Pointer-like devices are also used in laser alignment, construction, industrial manufacturing and automotive repair, and as aiming devices.
As a rule, green laser light at 532nm is the brightest laser color to the human eye at the same power. For example, a 200mW green laser will be 5X brighter than a 200mW of red or blue laser and 7X brighter a 200mW purple laser. The color does not matter for burning ability it is only the mW output power
However, the natural protective mechanisms of the eye – such as the blink reflex – are ineffective against lasers with an output power greater than five milliwatts, and severe retinal damage may occur, even after momentary exposure. Here's what the FDA advises: Never aim or shine a laser pointer at anyone.