Similarly, when a photon incident on a level system, and work to absorb it, will lead from the low-level atomic transition to the high energy level (so-called stimulated absorption); then, part of the transition to high-level atomic transition to the low level will and release a photon (the so-called stimulated emission). These movements are not isolated, but often simultaneously. The laser protection design of green laster pointer resists the current surge so as to make a long lifetime.When we create a condition, such as the use of appropriate media, cavity, enough external electric field is amplified by stimulated emission of radiation to be more than the stimulated absorption, so overall, there will be photon emission, resulting in the laser. Characteristics of the laser (a) ordinary light source is directional light in all directions. Make the emission of light propagation in one direction, you need to light a certain condenser fitted with devices such as car headlights, and searchlights were installed on the role of the condenser mirror, so that radiation is to bring together in one direction injection. The 100mW laser pointer supports the browsing of all formats of demonstrating files and websites.Laser emission of the laser, born in one direction injection, beam divergence is extremely small, only about 0.001 radians, nearly parallel. In 1962, the first human use of laser irradiation the moon, the moon's distance from the Earth about 38 million km, but the laser spot at the lunar surface less than two kilometers. If condenser works well, seemingly parallel light beam searchlight shooting the moon, according to its spot diameter will cover the entire moon. (B) Before the invention of the laser high brightness, high-voltage pulse in the artificial light source xenon lamp brightness maximum, comparable with the brightness of the sun, while the ruby laser laser light, xenon lamp can exceed several hundred billion times. The 5mW laser pointer is guaranteed for 1 year. Because the laser is extremely bright, ruby laser beam emitted illumination produced on the moon about it to illuminate distant objects. 0.02 lux (light intensity units), the color red, visible laser spot. If the most powerful searchlight with power moon light, the illumination produced only about a trillionth of Lux, the human eye can not detect. The main reason is the high brightness of laser light directed. A large number of photons concentrated in a very small space within the injection, the natural high energy density. (C) a very pure light color from the color of the light wavelength (or frequency) decision.The so-called 2.4GHz of Blue Laser Pointer refers to a working frequency band, which is between 2.405GHz and 2.485GHz (science, medicine, agriculture). A certain wavelength corresponding to the certain color. Wavelength distribution of sunlight in the range of about 0.76 microns to 0.4 microns, the corresponding color from red to purple, 7 colors, so the color of sunlight alone. Single-color light emission as monochromatic light source that emits a single wavelength of light. Such as krypton lights, helium lights, neon, hydrogen lights are monochromatic light sources, only a certain color of light emission. Although monochromatic single wavelength light source, but there is still a certain distribution.Working during the frequency band of 2.4GHz, 200mW Laser Pointer could obtain stronger signal transmittability. If only transmit red neon, color is very good, known as the highest monochromatic wavelength range of the distribution is still 0.00001 nm, so the neon red light, if carefully identified dozens of red still contains . Thus, the optical radiation of wavelength range of the more narrow distribution, the better the color. Output of the laser light, the wavelength distribution is very narrow, so very pure color.