Introduction of laser
Laser is the acronym of “light amplification by stimulated emission of radiation”.
The generation principle of laser
When the electron in the atom absorbs energy, it transitions from low energy level to high-energy level, and then drops from high-energy level to low energy level, the energy released is released in the form of photons. The optical properties of the induced (excited) photon beams (lasers) are highly consistent. Therefore, compared with ordinary light source, laser has better monochromatic and directional properties and higher brightness.
Advantages and characteristics of laser
1). Good monochromatic: the wavelength distribution of laser is narrow, so the color is very pure. The monochromatic property of laser is much better than that of other monochromatic light sources.
It is easy to filter and improve the signal-to-noise ratio. In material processing, the absorption spectrum of different materials is different, so the monochromaticity of laser can control the absorption depth and distribution, and the materials can be treated selectively and controlled. Monochromatic light is convenient in optical design, without dispersion difference, and the better monochromatic, the more stable the corresponding wavelength or frequency.
2). Strong directivity: the beam emitted by the laser is only emitted in one direction. Ordinary light source mostly scatters in all directions. If you want to make the light source converge to one part, you need to install auxiliary devices. For example, the headlamp of a car is equipped with a reflector with a concentrating effect to make the light converge and shoot in one direction.
The laser beam emitted by the laser only shoots in one direction, and the divergence of the beam is very small, almost parallel. The distance between the earth and the moon is about 380000 km. If a light beam is emitted to the moon, but the spot of the laser on the surface of the moon is less than two km, the seemingly parallel searchlight column will shoot to the moon and cover the whole moon according to its spot diameter.
3). Good coherence: coherence indicates the degree of light interference. If light is considered as wave, the closer the waveband is, the higher the coherence is. For example, when different waves collide on the water surface, they may enhance or cancel each other. The more random the waves, the weaker the interference.
The phase, wavelength and direction of the laser are consistent, which can maintain a strong wave and realize long-distance transmission. The light with high coherence has the characteristics of long-distance transmission and non diffusion, and has the advantages of focusing small spots through the lens. The generated light can be transmitted to other places and used as high-density light.
