laser

laser

Coherent radiation based on the principle of optical amplification of stimulated radiation. Laser has the following characteristics: ① Good directivity. The divergence solid angle of laser is extremely small, generally within the sphere of 10-5 ~ 10-8. The high directivity of laser means that the laser energy is concentrated in a very narrow beam. ② High brightness. The brightness of ordinary light source is very low, the brightness of the sun is about 103W/(cm2 sphericity), while the brightness of high-power laser is as high as101017w/(cm2 sphericity). ③ Good monochromaticity. The monochromaticity of laser is usually characterized by V/Δ V, where V is the frequency of the laser line center and Δ V is the line width. The better laser V/δV can reach10/kloc-0 ~1013. Good monochromaticity means good temporal coherence. ④ Good spatial coherence. The spatial coherence of ordinary light sources is very poor. When the optical path difference is several thousand times the wavelength, there is no interference. The laser is coherent in almost the whole wave field space.

The laser emitted by the laser device

Laser is widely used in ranging, radar, optical fiber communication, medicine and machining (welding, cutting, drilling, etc.). ), missile guidance and nuclear fusion test. High intensity laser has made a breakthrough in spectroscopy and opened up a new research field. The nonlinear effect caused by laser has created a new field of nonlinear optics. The excellent monochromaticity of laser provides a very favorable light source for accurate length measurement. The beat frequency technology of light wave can be developed by using good monochromaticity, and extremely slow speed (about 1 micron/second) and angular speed (about 10- 1 radian/second) can be measured. After the appearance of laser with good coherence, holography can enter the practical stage and be quickly applied to various fields. In the field of coherent information processing, laser has become an indispensable light source.