Since its invention, laser has been widely used in industrial processing, medical beauty, scientific research and other fields with its excellent characteristics. Laser has four main characteristics, including high brightness, good directivity, good monochromaticity and high coherence. These characteristics are interrelated, so that the laser can adapt to different scenes.
What are the characteristics of lasers?
High laser brightness
The laser with high brightness is mainly due to the high concentration of its beam. The high brightness of laser is also the embodiment of its high energy concentration. After focusing through the lens, thousands or even tens of thousands of degrees of high temperature can be formed near the focus, which makes it possible to process almost all materials.
High energy concentration is a very important characteristic of lasers. Because of this advantage, it can be widely used in industrial processing and medical fields.
monochrome
The color of light is determined by the wavelength of light, and light has a certain wavelength range. The narrower the wavelength range, the better the monochromaticity. For ordinary light sources, because the spectral linewidth is relatively large and the frequency range is too wide, the color displayed will be more complex.
Compared with ordinary light source, the linewidth of laser is much narrower. However, the linewidth of laser is limited by many factors, and it is almost impossible to reach the theoretical level. For example, temperature change, slight vibration of the laser, air flow in the volume optics and external pumping will lead to unstable resonant frequency, resulting in reduced performance.
Good directivity
Light from ordinary light sources travels in all directions with large divergence angles. Compared with ordinary light source, the divergence angle of laser is small, and it is almost parallel. The light emitted by the laser is a polarized light with fixed direction. A simple example can express this intuitively: laser does not refract on water.
Among all kinds of lasers, gas lasers are the most prominent in directivity, followed by solid-state lasers. In this regard, the performance of semiconductor lasers is slightly worse.
Good consistency
Light waves consist of innumerable photons. Due to the resonance principle, the light quantum emitted from the laser is consistent in wavelength, frequency and polarization direction, which makes it have very strong interference force. We also usually call laser coherent light. It is precisely because lasers are much more coherent than ordinary light sources.
Using laser as the source of holography is also characterized by good coherence.