Early laser Pointers used a helium-neon (HeNe) gas laser with a wavelength of 633 nanometers (nm), which was typically used to produce laser beams with energies of no more than 1mW. The cheapest laser Pointers use deep red laser diodes with wavelengths approaching 670/650nm. The more expensive ones use a red-orange diode with a wavelength of 635nm, which is easier for the human eye to detect. There are also laser Pointers in other colors, the most common being green light with a wavelength of 532nm.
The nonlinear crystal is excited by 808nm infrared laser, 1064nm infrared light is generated, and 532nm green light is generated by frequency doubling, which belongs to solid laser. Some green laser pointer operate in pulsed or quasi-continuous mode to reduce cooling problems and extend battery life. The announced green-light laser, which does not require frequency doubling, is much more efficient. Even low-power green light can be seen at night due to Rayleigh scattering of atmospheric molecules, and the laser pointer is often used by astronomy enthusiasts to point out stars and constellations. The green laser pointer can have a variety of output powers. 5mW is safest to use and is also visible in dim lighting, so no more power is required for pointing purposes.
The green light diode laser is one of the newest laser diodes, but it has been used in many applications, mainly laser Pointers and projectors. During presentations, business people and teachers use these laser Pointers in class to draw attention to certain aspects of a board or planning presentation. Land surveyors use more powerful laser Pointers to survey land. Laser projectors used to project movies make use of green diodes to create a wider range of colors.
