What is a CO2 Laser?

The carbon dioxide laser (CO2 laser) was one of the earliest gas lasers to be developed. Carbon dioxide lasers are the highest-power continuous wave lasers that are currently available. They are also quite efficient: the ratio of output power to pump power can be as large as 20%. The CO2 laser produces a beam of infrared light with the principal wavelength bands centering on 9.6 and 10.6 micrometers (μm).

Because CO2 lasers operate in the infrared, special materials are necessary for their construction. Typically, the mirrors are silvered, while  lenses are made of either germanium or zinc selenide. For high power applications, gold mirrors and zinc selenide lenses are preferred.

CO2 Laser Applications:

What can a CO2 laser do ? Because of the high power levels available (combined with reasonable cost for the laser), CO2 lasers are frequently used in industrial applications for cutting and welding, while lower power level lasers are used for engraving.

Types of CO2 Laser Source Tubes

Glass CO2 Laser Tube

Advantages of Glass Tubes:

Glass tubes are often an enticing option due to their low cost. This is due to the glass tubes being low cost themselves and the CO2 laser is powered by direct current(DC) which is inexpensive in itself.

Disadvantages of Glass Tubes:

Glass is a poor thermal conductor, which means there is a need for a water cooling system. This is needed to assist in the removal of heat. Without the water cooling system, a glass tube would easily overheat and become inoperable. This cooling system may also introduce more points of failure needed to be maintained. This increases the glass tube rate of failure. Gives it a short life.

Other disadvantages:

  • Large Volume
  • Poor Beam Mode (the cutting line is thick)
  • Slow Response Speed
  • The power-adjustability is poor, and the same power laser has different effects on different materials.

(picture of metal laser tube)

CO2 Ceramic Tube Laser or Ceramic Core CO2 Laser Technology

Metal lasers have reliability issues due to the oxidation caused by the exposure of metal to oxygen in the gas mixture of CO2 lasers. Ceramic CO2 laser tube technology solves these problems by moving all the reactive components to the outside of the laser tube leaving only pure clean Alumina (Al2O3) ceramic in contact with reactive gasses. Due to its chemical makeup, Alumina does not react with the gas. Alumina can also be fired at very high temperatures as part of the cleaning process. This further assures there are no organic contaminants from laser tube manufacturing, that remains inside the laser tube to react with the gas.

The ceramic CO2 laser tube is also the optical backbone that holds the resonator optics. The CTE (coefficient of thermal expansion) of alumina is 1/3 the CTE of aluminum. Since laser tube thermal variations have a direct impact on laser stability, Iradion's Ceramic CO2 laser tube has significantly better stability performance when compared with metal-based CO2 lasers. Ceramic CO2 laser tubes also enables gas mixtures of comparatively high pressure to be used. Ceramic CO2 laser tubes allow for high pressure gas mixes and provide for faster rise and fall speed as well as much better power stability.

(picture of glass laser tube)

Metal CO2 Laser Tube

Advantages of Metal Tube:

Metal CO2 laser tubes or RF(radio frequency) meta tubes are air-cooled and the gas is excited by radiofrequency alternating current (RF). Thus, properly regulating the temperature of the metal tube only requires the help of directly built-in fans. This reduces the overall space needed for the laser machine and the need for external equipment like a water cooling system.

Other Advantages Are:

  • small size
  • fully-sealed off
  • compact design
  • maintenance-free
  • excellent modulation
  • high-quality laser beam
  • high injection power density
  • excellent power stability
  • high operational reliability
  • long service life
  • low cost (However, more expensive than glass tubes)

Problem with Metal Tubes:

Metal is highly reactive to the gas mixture produced by CO2 lasers. This occurs over time as the internal components wear out leaving fresh aluminium exposed. This aluminium then reacts to the oxygen in the laser's gas causing oxidation, changing the composition of the original gas mixture.

The video bellow will go into more detail on ceramic core