The main characteristics of lasers

The main characteristics of lasers

The generation of lasers The theory of “spontaneous and stimulated radiation” proposed by Einstein in 1916 is the physical foundation of modern laser system. The interaction between photons and atoms may cause three types of transition processes: stimulated absorption, spontaneous emission, and stimulated emission.

The main characteristics of lasers are:

1. Good directionality: Since only the light beam propagating along the axis of the resonant cavity can form oscillation and continuous amplification, the laser output from the laser has a particularly small divergence Angle and excellent directionality, making it an ideal parallel light source.

2. High brightness: Due to its excellent directionality, laser energy is highly concentrated in space, thus enabling it to have a very high intensity. The general brightness of sunlight is approximately 100W/cm ². The light intensity of a helium-neon laser with a power of several milliwatts can be hundreds of times higher than that of sunlight. A laser that operates in a pulsed

manner can have a light intensity 107 to 1014 times higher than that of sunlight.

3. Good monochromaticity: Due to the fact that the photons produced by stimulated radiation have the same frequency and are limited by the resonant cavity, only light of a definite wavelength can oscillate and be output. Therefore, lasers have excellent monochromaticity.

4. Good coherence: Ordinary light produced by spontaneous radiation is incoherent light, while the characteristics of light emitted by stimulated radiation make lasers have good coherence. These four major characteristics provide new diagnostic techniques and image recognition technologies for medicine and biology.

The hazards of lasers and safety measures

The potential harm that lasers may cause to the human body can be divided into two categories. One type is direct harm, that is, the light radiation of lasers exceeding the safety threshold causes damage to the eyes, skin, nervous system and internal organs. Another category is the indirect hazards caused by factors such as high voltage electricity, noise, low-temperature refrigerants and power sources. Therefore, corresponding safety measures should be taken: monitoring and management of the laser system and the working environment, as well as personal protection.