Views:3 Author:Site Editor Publish Time: 2019-01-25 Origin:Site
It is a very efficient laser, with a conversion efficiency of 10% as a commercial model, so co2 lasers are widely used for laser cutting, welding, drilling and surface treatment. For commercial use, lasers can reach several kilowatts, which is currently the most powerful material treated laser.
In 1964, the wavelength of 10.6m was used. Because it is a very efficient laser, with a conversion efficiency of 10% as a commercial model, co2 lasers are widely used for laser cutting, welding, drilling and surface treatment. For commercial use, lasers can reach several kilowatts, which is currently the most powerful material treated laser.
1. Operation principle
The main substance is CO2 laser tube. As the maxwell - boltzmann law of distribution says, in plasma, molecules take on many states of excitation. Some will have a high energy state (00o1) that behaves as an asymmetric oscillating state. Such molecules can also accidentally lose energy when they collide with a hollow wall or naturally emit it. This high-energy state is naturally emitted down to a symmetrical oscillating state (10o0) and emits photons that can travel in any direction (a beam of 10.6 m wavelength). Incidentally, one of these photons will travel down the cavity of the optical axis and will also oscillate in the resonant mirror.
Figure 1 shows a simple diagram of the molecular energy levels of carbon dioxide
In principle, the co2 laser works on a mixture of carbon dioxide, helium and nitrogen. Nitrogen ACTS as a buffer gas and its molecules resonate to deliver stimulus energy to carbon dioxide molecules. Because relaxation levels are bottlenecks, helium's job is to transfer energy to helium atoms as a thermal trap.
2, the type of carbon dioxide laser
The way waste heat is rejected has great influence on the design of laser system. The first method is based on the automatic processing of naturally diffused hot gas into the pipe wall, which operates by sealing and slow axial flow laser. The second, based on forced convection of gases, operates by means of a fast-axis laser. In general, there are five main types of co2 lasers:
Sealed or non-flow
Slow axial flow
Fast axial flow
Fast transverse flow
Lateral excited atmosphere (TEA)
Sealed or flowless carbon dioxide lasers are commonly used for beam deflection laser marking. 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 a new one that can be reinflated so it is easy to maintain. This eliminates the need for a separate gas supply system. Only a few connections need to be made on the laser head. So it's compact and lightweight. But its energy output is low (usually less than 200 watts).
The TEA carbon dioxide laser is commonly used in shield making. Can only operate in pulse mode. The air flow is low and the pressure is high. The excitation voltage is about 10,000 volts. The energy distribution of the laser beam is uniform over a relatively large area. It has a maximum energy of 1012 watts and a very small pulse width. However, this form of laser is difficult to focus on small points because of the multi-state operation.
3. Power supply of the pump
For CW co2 laser, generally speaking, there are three main ways to power the pump. For example: direct current (DC), high frequency (HF), radio frequency (RF). Dc power supply design is the simplest. In high frequency power supply the electrons alternate between 20 and 50 kilohertz. Compared with direct current, high frequency power supply is compact in size and high in efficiency. In rf power supply, electrons alternate between frequencies of 2 and 100 MHZ. Compared with direct current, its voltage and efficiency are lower.