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.