Three characteristics of laser pointer
The laser has high monochromaticity, high brightness and high directivity. 1. The high monochromaticity of the high power laser pointer. Commonly used light sources in physical therapy include heat sources (such as incandescent lamps, infrared lamps) and gas discharge light sources (such as ultraviolet lamps). The luminescent material of this kind of light source is more complicated, it produces photons in the form of spontaneous emission, and the emitted light is very impure, and their spectral range is connected or band-shaped.
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2. The high directionality of the laser. The scattering angle of laser light is very small, usually calculated in milli-arc. For example, the scattering angle of the ruby laser is 0.18°, and the helium-neon laser is only 1 milliradian. Therefore, lasers are almost equally collimated beams, which have a high degree of directivity during their propagation. When the flashlight is illuminated, due to the large scattering angle of the light, the light will spread out and form a large and dim optical disk after reaching a distance of several tens of meters. Because of the small scattering angle, the laser can be collimated to a long-distance target. In 1962, the laser was launched to the moon. After a process of more than 400,000 kilometers, the diameter of the scattered light spot was only more than two kilometers. Using the collimation of the laser for distance measurement, the error from the earth to the moon does not exceed 1.5m.
2021-09-22 11:32:52
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