The Laser pointer is a low-cost portable laser that can be carried around. It is designed to point out the area of the slide or picture to be displayed during presentations, instead of holding wooden sticks or retractable metal pointers. It is superior to the old pointer because it can be used hundreds of feet away in dark areas, and it can accurately produce bright spots where users need them. It has also become a universal pointing tool and has become so commonplace that laws restricting its use have been passed.
It is generally believed that the possibility of using a laser pointer to be dangerous is limited to the unprotected eyes of individuals who may be exposed to a direct beam (observation within the beam). Usually there is no skin hazard. For devices that emit Class II levels, the natural aversive reaction of the eye or blinking reflection (t = 0.25 s) usually limits the exposure in the beam to a safe level (ANSI Z136.1 standard "Safe use of lasers" "[1] recommendations Use a 5mW visible diode laser for deliberate intra-beam exposure. For exposures of around 0.25 s, an eye pattern filter with an optical density (OD) of 0.7 may be required. Longer exposures will require higher OD. Viewing conditions do not require Goggles.
However, there are now more powerful laser laser engraver. These devices are usually imported into the United States without proper manufacturer certification or labels. One such indicator (reportedly imported from Russia) emits a green beam from a diode-pumped frequency doubled Nd:YAG laser operating at 532 nm. The beam is the envelope of a series of 40 ns pulses, which emit 0.5 µJ/pulse energy at approximately 1.7 KHz. This corresponds to an average power of approximately 0.85 mW. Each pulse emitted by the pointer is 12 times higher than the MPE limit allowed by the ANSI Z136 standard-therefore, if viewed directly, this type of pointer has a great potential eye hazard!
Technically, the term laser is an acronym that stands for "light amplification by stimulated emission of radiation", but the term has become so common that it is no longer capitalized. Radiation is the light emitted from the laser. The human eye can or cannot see this light. Technically, only some lasers use optical amplification, but the term laser is still used for devices that produce monochromatic (all colors or wavelengths), coherent (light waves are similar enough to move in one direction) radiation.
All lasers have laser medium, energy source and resonator. The laser medium is a material that can be pumped (excited) to a higher energy state by an energy source (such as light or electricity). After pumping, the laser medium can release energy as monochromatic radiation. The resonator is the area that allows the released energy to accumulate before it is released. The basic resonator is a pair of mirrors at both ends of the laser medium. A mirror is completely reflective, so all light reflected to it will be reflected back into the blue laser pointer. The other is partially reflective, so some of the light that hits it will be reflected back into the laser medium, and some of the light will pass through the medium and exit the laser. A pair of mirrors reflects light back and forth in the laser medium and aligns it in one direction, thereby creating light coherence.