What are the characteristics of laser and important
???????The laser emission principle and the particularity of the production process determine that the laser has the characteristics that ordinary light does not have: three good (good monochromaticity, good coherence, good directionality) and one high (high brightness).
1 Good monochromaticity: The photons emitted by ordinary light sources are different in frequency, so they contain various colors. The frequency of each photon emitted by the laser is the same, so the laser is the best monochromatic light source.
Because the biological effect of light strongly depends on the wavelength of light, the monochromaticity of laser light has important applications in clinical selective treatment. In addition, the monochromatic characteristics of lasers are also widely used in spectroscopy and optical measurement, and have become an important means of basic medical research and clinical diagnosis.
2 Good coherence: Because the photons of the stimulated radiation are consistent in phase, coupled with the mode selection effect of the resonator, there is a fixed phase relationship between the points on the cross section of the laser beam, so the spatial coherence of the laser is very good (The ordinary light generated by spontaneous radiation is incoherent light). The laser provides us with the best coherent light source. It is precisely because of the advent of lasers that the rapid development of coherent technology and the realization of holographic technology.
3 Good directivity: The divergence angle of the laser beam is very small, almost a parallel light, and the diameter of the spot formed by the laser irradiation on the moon is only about 1 km. The light emitted by the ordinary light source is directed in all directions.In order to concentrate the ordinary light in a certain direction, a condensing device is often used, but even the best searchlight, such as projecting its light on the moon, the spot diameter will be expanded to 1 000 Kilometers above.
The good directivity of the laser beam in medical applications is mainly because the laser energy can be highly concentrated in space, so that the laser beam can be made into a laser scalpel. In addition, from geometric optics, it can be seen that the better the parallelism of the beam, the smaller the focal spot size obtained by focusing, and the laser monochromaticity is better.After focusing, there is no dispersion aberration, which further reduces the spot size, which can reach below the micron level It can even be used as a fine 'scalpel' for cutting cells or molecules.
4 High brightness: The brightness of the laser can be 1012-1019 times higher than that of the ordinary light source. It is the brightest light source at present, and the strong laser can even produce hundreds of millions of degrees of high temperature. The high energy of laser is one of the most valuable basic characteristics to ensure the effectiveness of laser clinical treatment. The high energy of laser can also be used in laser processing industry and national defense.