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The CO2 Laser typically uses a mix of neon, nitrogen and carbon dioxide as the lasing medium. Like other discharge pumped lasers, it consists of a gas filled lasing chamber between a normal mirror and a mirror that is partially transparent to the lasers wavelength. The chamber also has discharge electrodes. To fire the laser a high voltage supply(typically 10kV-20kV) is connected to the electrodes and a starting pulse(25kV+) is administred. This starts an electron flow through the 'helping' gasses(neon and nitrogen). Some these electrons collide with the CO2 molecules. This creates a state of high vibration energy in in the molecule. When the vibration decays back to normal, an pulse of EM energy is released. This light has a typical wavelength of between 9um and 12um(normal peak wavelengt is around 10.6um). This energy is reflected between the mirrors, and when it escapes thrugh the semitransparent mirror, it forms the laser beam. Since the high energies caused by the lasing process breakes down the CO2, the lasers often have a circulation system, that pumps new gas in and used out.

       new gas
     from pumping
       _| |__________________________
     !#                              #|
     !:               Chamber        :;--------------
     !:                              :;--------------
     !#__________________________   _#|   Beam
      #                          | | #
      #                          ||| #


: IR transparent material
# electrodes
! mirror
; semi transparent mirror

These lasers have high effects and easily comes up over 50W. Due to the high wavelength(mid IR) special optics are needed. The end of the chamber has a pane of germanium, natrium chloride (salt) or zinc selenide, since normal glass isn't very transparent at these frequencies. The CO2 lasers are used in industry for welding and cutting. It is also used as a surgical tool.
CO2 Lasers have their own website: www.synrad.com, where one can learn about all their applications. Synrad (An Excel Technology Company) advertises in NASA's Tech Briefs with infomercials touting:

Drilling Ceramic with CO2 Lasers

The cutting and drilling process involves more care on ceramics than it does with other substances, and the electronics industry has taken advantage of the speed and micro adaptablities. The danger is overheating the brittle material. Now, 75 micron holes can be drilled into Alumina .015"ceramic without leaving dross if one uses a pulse mode at 240 watts.

The other critical element in the products' outcome, is the assist gas pressure. This procedure prevents the formation of dross by the exit hole by stemming over expansion of spewed ceramic material. The gas protects the focusing optic from this splatter.

The gas type used makes a difference in chemical quality.

Laser Cutting 75Cr-1 Steel

This 75Cr-1 steel is the extra durable variety used in power machinery cutting blades.
CO2 lasers at 240 watts will leave only a small amount of dross at the lower end of the work.

.1" thick steel can be cut with a 240 watt Synrad laser at 25" per minute.

Laser Marking Brake Pads

Both sides of the part can be engraved with a mark.
The contact side of the brake pad can have an indented engraving, while the reverse painted side can have a larger contrasting imprint. This application can be done with 15 watts of power at 65" per second.

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