Brief Introduction to CO2 Laser Working Principle and Classification

The carbon dioxide laser was first used in 1964 with a wavelength of 10.6 μm. Because this is a very efficient laser, as a commercial model for its conversion efficiency of 10%, so carbon dioxide laser widely used in laser cutting, welding, drilling and surface treatment. As a commercial application of laser up to several kilowatts, which is currently the strongest material handling laser.

1.The operating principle

Carbon dioxide laser is a molecular laser. The main substance is carbon dioxide molecules. It can express a variety of energy state which depends on its vibration and rotation of the form may be. The mixed gas in the carbon dioxide is a plasma (plasma) formed by low-pressure gas (usually 30-50 torr) due to electron release. As in the Maxwell-Boltzmann distribution law, in the plasma, the molecules exhibit a variety of excited states. Some will exhibit a high energy state (00o1) which behaves as an asymmetrical swing state. When the collision with the hollow wall or natural distribution, this molecule will accidentally lose energy. This high-energy state will naturally descend to a symmetrical wobble (10o0) and radiate a photon (a 10.6μm light beam) that may propagate in any direction. Occasionally, a kind of photon that will travel down the cavity of the optical axis will also swing in the resonance mirror.

In general, carbon dioxide laser working material is composed of carbon dioxide, helium, nitrogen mixture. Nitrogen acts as a buffer gas as well as its molecules resonate to deliver energy to the carbon dioxide molecules. Because the level of relaxation is the bottleneck, the helium acts as a heat sink to deliver energy to the helium atoms.

2.The type of carbon dioxide laser

Waste heat rejection of the way the laser system design has a great impact. In principle, there are two possible ways. The first way is based on automatic processing of natural diffusion of hot air to the pipe wall, the operating principle is sealed and slow axial laser. The second is based on gas forced convection, its operating principle is fast axial laser. In general, there are five main types of carbon dioxide laser:

Sealed or no flow

Slow axial flow

Fast axial flow

Fast horizontal flow

Horizontal excited atmosphere (TEA)

Sealed or flowless carbon dioxide lasers are usually marked with a laser for beam deflection. Its discharge tube is completely sealed. The quality of this laser beam is very good. And in most cases the entire discharge tube can be replaced with old and new can be re-filling so easy to maintain. This eliminates the need for a separate gas supply system. Only need to do less in the laser head connection. So it is both compact and lightweight. But its energy output is low (usually less than 200 watts).

TEA carbon dioxide laser is usually used in the manufacture of protective cover. Can only operate in the pulse situation. Low air flow and high pressure. Its excitation voltage is about ten thousand volts. The distribution of the laser beam energy in the relatively large area is uniform. Its maximum energy can reach 1012 watts and its pulse width is very small. However, this type of laser is difficult to concentrate at a small point due to the multi-state operation.

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