Laser, is a kind of light that nature does not exist, and is stimulated and has the characteristics of good directivity, high brightness, good monochromaticity and good coherence.

The mechanism of laser generation can be traced back to the hypothesis put forward by Einstein in explaining the law of blackbody radiation in 1917 that the absorption and emission of light can undergo three basic processes: stimulated absorption, stimulated emission and spontaneous emission. It is well known that the luminescence of any kind of light source is related to the movement of particles inside its material. When a particle (atom, molecule or ion) at a low level absorbs an appropriate frequency and external energy (light) is excited to transition to a corresponding high level (excited absorption), it always tries to transition to a lower level Go, and release excess energy in the form of photons.

If the light is emitted spontaneously without spontaneous photons (spontaneous emission), then the released light is normal light (such as electric lights, neon lights, etc.), which is characterized by the frequency of light size, direction and pace are Very inconsistent.

However, if the excess energy is released as a photon (stimulated emission) when the transition from a high energy level to a low energy level is made by the direct action of external photons, the released photons are aligned with the incoming photons in terms of frequency, phase, propagation direction It means that the external light is strengthened, which we call light amplification.

The laser generation needs to meet three conditions: the number of particles reversed, resonant cavity feedback and meet the threshold conditions. By stimulated absorption, the number of particles at high energy level is higher (the number of particles is reversed) at a lower energy level, and parallel reflection surfaces capable of reflecting photons are formed at both ends of the active region to form a resonant cavity The gain is greater than the loss, that is, the new photons generated at the same time is greater than the number of photons absorbed by the scattering. Only meet these three conditions, it is possible to produce laser.

Laser characteristics

The reason why the laser is known as the magic of light, because it has four common features do not have the light.

1.Good directivity - Ordinary light sources (sun, incandescent or fluorescent) shine in all directions and the laser's light direction can be limited to less than a few milliradians in the solid angle, which increases the illuminance in the direction of illumination by 10 million Times The laser diffuses to less than 1 meter in diameter every 200 kilometers. If it reaches the moon of 3.8 × 105 km from the earth, the light beam will not spread more than 2 kilometers. However, the general searchlight will spread to several tens of meters only a few kilometers away.

Laser collimation, guidance and ranging is the use of good directional characteristics.

2.Brightness - the laser is the brightest light source of the moment, only an instant flash of hydrogen bomb explosion can be compared with it. Sunlight brightness is about 1.865 × 109cd / m2, and a high-power laser output brightness can be higher than the brightness of sunlight 7 to 14 orders of magnitude.

3.Although the total energy of the laser is not necessarily large, high energy and tens of thousands of degrees Celsius or even millions of degrees Celsius are easily generated at a tiny spot due to the high concentration of energy. Practical applications such as laser drilling, cutting, welding, and laser surgery take advantage of this feature.

3.Monochromatic good - light is an electromagnetic wave. The color of light depends on its wavelength. Ordinary light source emits light usually contains a variety of wavelengths, is a mixture of various colors of light. Sunlight contains red, yellow, green, green, blue, purple seven kinds of visible light and infrared light, ultraviolet light and other invisible light.

4.Coherence is good - interference is a property of volatility. Based on the laser's high directivity and high monochromatic properties, it is bound to be extremely coherent light. This feature of laser makes holography a reality.

Application range

It can used on lots production lines, like Food medicine metal  wood car garments ans so on.