In wikipedia.org

A laser pointer is a portable, pen-sized laser designed to be held in the hand, and most commonly used to project a point of light to highlight items of interest during a presentation. Most laser pointers have low enough power that the projected beam presents a minimal hazard to eyes for incidental exposure. Consequently, beams from laser pointers are generally not visible from the side in normal clear air, but only visible as a point of light where the beam strikes a diffusely reflective surface. Some higher powered laser pointers are faintly visible via Rayleigh scattering when viewed from the side in moderately to dimly lit conditions.

The early laser pointers were helium-neon (HeNe) gas lasers and generated laser radiation at 633 nanometer (nm). Usually designed to produce a laser beam with an output power no greater than 1 milliwatt (mW). The least expensive laser pointers use a deep red laser diode near the 670/650 nanometers (nm) wavelength. Slightly more expensive ones use a red-orange 635 nm diode, making them more easily visible than their 670 nm counterparts due to the greater sensitivity of the human eye at 635 nm. Other colors are possible too, with the 532 nm green laser being the most common alternative. In the past few years, yellow-orange laser pointers, at 593.5 nm, have been made available. Recently (September 2005), handheld blue laser pointers at 473 nm have also become available.

The apparent brightness of a spot from a laser beam depends not only on the optical power of the laser and the reflectivity of the surface, but also on the color response of the human eye. For the same optical power, the green laser will seem brighter than other colors because the human eye is most sensitive at low light levels in the green region of the spectrum (wavelength 520 - 570 nm. Sensitivity decreases for redder or bluer wavelengths.

The output power of a laser pointer is measured in milliwatts (mW). In the US lasers are classified by the American National Standard[1] and by the Food and Drug Administration (FDA). Visible laser pointers (400-700 nm) operating at less than 1 mW power are Class 2 and visible laser pointers operating with 1-5 mW power are Class 3a. Class 3b lasers emit power between 5 mW and 500 mW (0.5 watt) and are not allowed for laser pointers. Class 3b lasers can present a variety of hazards to personnel through ocular exposure to direct beams.

http://en.wikipedia.org/wiki/Laser_pointer

Copyright © 2017 BeamQ Lasers.