The basic principles of CO2 laser
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Source: China Network Laser time to add 2007-6-7 8:49:15
 
 
The basic principles of CO2 laser, the agency introduced

CO2 lasers and highly efficient work of the media not to cause damage to launch a 10.6μm wavelength of the laser is not visible, is a more ideal laser. By the work of the gas can be in the form of a closed-cycle and, by way of encouraging incentives at power, chemical inspire, motivate heat, light and nuclear incentives, and other incentives. In the medical use of CO2 laser power is almost 100 percent incentive.

CO2 lasers operating principle: with other elements, like laser, CO2 laser principle of the stimulated emission process more complicated. There are three different elements of the campaign, that is, electronic elements in the movement, the movement has decided to elements of the electronic energy state; Second, the atoms in molecular vibration, that is, the atoms in molecules around the location of the balance of its non-stop for a cyclical vibration - and Determined by the molecular vibration energy state; Third, molecular rotation, that is, molecules in space as a whole is a continuous rotation, the molecule that determines the movement of molecules can rotate state. Campaign elements are very complex energy level is also very complicated.

CO2 molecular asymmetric linear elements, the two oxygen atoms in the carbon atoms on either side, is expressed by the atomic equilibrium position. Elements in the movement of the atom has to balance its position around the non-stop vibration. According to the molecular vibration theory, CO2 there are three different vibration mode: ¢Ù two oxygen atoms along the molecular axis, in the opposite direction to the vibration, the vibration of the two oxygen at the same time achieve the maximum vibration and balanced value, while elements of Stationary carbon atoms, and thus the vibration was called symmetric vibration. ¢Ú two oxygen atoms in the molecule axis perpendicular to the direction of vibration, and vibration in the same direction, and the carbon atoms are in the opposite direction perpendicular to the axis molecular vibration. As the three atoms of the vibration is synchronized, also known as the deformation vibration. ¢Û three atomic vibrations along the axis of symmetry, in which the carbon atoms in the direction of vibration and the two oxygen atoms on the contrary, also known as anti-symmetric to the vibration. In this way three different vibration, different groups have identified the energy level.

CO2 laser to stimulate the process: CO2 laser, the main material from the work of CO2, nitrogen, helium gas of the three components. In which CO2 laser radiation is produced gas, nitrogen and helium for the auxiliary gas. To join the helium, you can speed up the 010-level pre-heat the process of relaxation, it is conducive to the laser energy level 100 and 020 of the time. Adding nitrogen in the main CO2 laser energy transfer in the starting role for CO2 laser energy level on the number of particles and the accumulation of highly efficient high-power laser output has played a strong role.

CO2 laser molecular-level transition plans

CO2 laser excitation conditions: discharge tube, normally enter dozens or hundreds of mA DC mA of current. Discharge, gas discharge tube in a mixture of nitrogen molecules due to the impact of electronic excited to be together. At this time inspired by the CO2 and nitrogen molecules will be a collision between molecules, N2 molecules transfer their energy to the CO2 molecules, CO2 from the low-molecular-level transition to high-energy level to create population inversion issued by the laser.

Structure: ¢Ù laser: laser machine is the most critical components. Often made of hard glass, generally sleeve-layer structure. The innermost layer is a discharge tube, layer 2 casing for water-cooled, the outermost layer of gas to control. Carbon dioxide laser discharge tube diameter than the He-Ne laser tube rough. Generally speaking, the discharge tube thickness of no effect on output power, mainly taking into account the size of the spot caused by diffraction effects, according to a long tube. Possession of a little rough, short of the tube is small. The length of discharge tube and in direct proportion to the output power. To a certain length, per meter length of the discharge tube output power with a total length of the increase. Add water cooling kit is aimed at working gas, so that the output power stability. In the discharge tube with two ends of gas pipes to connect, that is, the gas pipe at one end of the discharge tube with a small heart, and the other side of the spiral back through the trachea connected with the discharge tube, which can make the gas discharge tube with gas pipe in the cycle Flow of the gas discharge tube in the exchange at any time.

CO2 lasers chart

Optical cavity: CO2 laser resonator cavity Pingao common, with K8 optical mirrors or optical quartz glass, processed at National Cheng Kung University radius of curvature of the concave mirror, mirror-plated on a high reflectivity of the metal film - gold-plated membrane, 10.6μm wavelength in the Office of the reflection rate of 98.8 percent, and the nature of the chemical stability. Carbon dioxide issued by the infrared light. Therefore, the application needs of mirrors infrared light through the material, because the infrared optical glass on the impenetrable. Total reflection in the mirror on the request to open a small hole at the center. Re-seal on a 10.6μm through the infrared laser materials, gas to be closed. This makes the laser cavity resonance part of the output from this small cavity, to form a bouquet of laser.

Power and pumping: a closed CO2 laser discharge current of the smaller, cold electrode, the cathode with nickel or molybdenum film made cylinder-shaped piece. 30 ~ 40mA current work, the size of the cathode cylinder 500cm2, the lens will not be polluted in the cathode between the lens and a light bar.

Pump used for DC power to stimulate. Incentive DC power CO2 laser principle, direct current voltage for the city to exchange voltage transformer used to upgrade, the high-voltage and high voltage rectifier filter was added to the high-voltage laser on the tube.