Laser pointers are widely used in daily life, such as the scene of a ball game, the scene of a singer's concert, and so on. There is the light of a laser pointer. So, what is the principle of the laser pointer? Laser pointer, also known as laser pointer, pointing star pointer, etc., is a processed transmitter. The common laser pointers have red light, blue light, green light, blue-violet light and so on. The principle of the laser pointer for each color light is different. Common laser pointers have red light (λ=650～660nm, 635nm) , Green light (λ=515-520nm, 532nm), blue light (λ=445～450nm) and blue-violet light (λ=405nm), etc.
The three conditions for laser generation are: to achieve population inversion, to meet threshold conditions and resonance conditions. The primary condition for generating stimulated emission of light is population inversion. In semiconductors, electrons in the valence band are pumped to the conduction band.
In order to obtain ion number inversion, heavily doped P-type and N-type materials are usually used to form a PN junction. In this way, under the action of an applied voltage, ion number inversion occurs near the junction area—at high Fermi level EFC Electrons are stored in the conduction band below, and holes are stored in the valence band above the low Fermi level EFV.
Achieving population inversion is a necessary condition for green laser pointer generation, but it is not a sufficient condition. To generate laser light, a resonant cavity with extremely low loss is also necessary. The main part of the resonant cavity is two parallel mirrors. The stimulated radiation emitted by the active material is reflected back and forth between the two mirrors, constantly causing new The stimulated radiation makes it constantly amplified. When the stimulated radiation meets the threshold condition and resonance condition, light oscillation can be formed, and stable laser can be output.
Finally, advise friends not to irradiate the eyes directly when using the laser pointer. It may cause severe damage to the retina and macula, and even permanent blindness. It is not suitable for children. Want to know more about laser pointer safety.