A laser is a device capable of emitting lasers. According to the working medium, lasers can be divided into four categories: gas lasers, solid lasers, semiconductor lasers, and dye lasers. Recently, free electron green laser pointers have been developed. High-power lasers are usually Pulse output.
Except for free electron lasers, the basic working principles of all lasers are the same. The indispensable conditions for generating a laser are that the number of particles is reversed and the gain is greater than the loss, so the essential components of the device are an excitation (or pumping) source and a working medium with a metastable energy level. Excitation is that the working medium excites to an excited state after absorbing external energy, creating conditions for achieving and maintaining the number of particles inversion. Excitation methods include optical excitation, electrical excitation, chemical excitation and nuclear energy excitation.
The working medium has a metastable energy level to make the stimulated radiation dominate, thereby achieving optical amplification. A common component of green laser pointers is a resonant cavity, but a resonant cavity (see Optical Resonant Cavity) is not an indispensable component. A resonant cavity allows photons in the cavity to have a consistent frequency, phase, and running direction, thereby The laser has good directivity and coherence. In addition, it can shorten the length of the working material very well, and it can also adjust the mode of the generated laser (that is, mode selection) by changing the length of the resonant cavity, so the general laser has a resonant cavity.
1. Working substance: The core of the green laser pointer, only the substance that can achieve the energy level transition can be used as the working substance of the laser.
2. Incentive energy: Its role is to give working substance energy to excite atoms from low energy levels to high energy levels of external energy. There can usually be light, thermal, electrical, chemical, etc.
3. Optical resonant cavity: The first effect is to continuously stimulate the stimulated radiation of the working substance; the second is to continuously accelerate the photons; the third is to limit the direction of the green laser pointer output. The simplest optical resonator consists of two parallel mirrors placed at both ends of a helium-neon laser. When some neon atoms transition between the two energy levels where the number of particles is reversed, and radiate photons parallel to the laser direction, these photons will be reflected back and forth between the two mirrors, so they will continue to cause stimulated radiation, Very fast lasers are produced very quickly.