Glossary · Processes
CO₂ laser
A laser in which a gas mixture in a tube generates invisible infrared light. It cuts wood and acrylic very cleanly and also engraves glass and clear acrylic.
Explained in more detail
The CO₂ laser works with a gas mixture of carbon dioxide, nitrogen and helium and emits at 10,600 nm (10.6 µm) in the far infrared. In hobby and workshop machines, the gas sits in a glass tube of 40 to 150 W that is water-cooled. More expensive machines use cooled metal tubes (RF tubes), which allow finer engraving. The beam is steered to the head by three mirrors and focused there by a lens, with focal lengths of 1.5 to 4 inches (38.1 to 101.6 mm) being usual. Almost all organic materials and acrylic of any colour absorb 10.6 µm very well, while bare metal largely reflects it.
Where does the term come from?
CO₂ is the chemical formula for carbon dioxide, the active laser medium. The CO₂ laser was developed by Kumar Patel at Bell Labs in 1964.
In practice
- Glass tubes age: depending on quality and use, expect a few thousand operating hours, fewer at high continuous power.
- Keep the cooling water temperature roughly between 15 and 25 °C, otherwise power drops and the tube ages faster.
- The mirrors must be aligned exactly. If the laser loses power at the edge of the work area, the mirror alignment has often shifted.
- A CO₂ laser cuts clear acrylic with a polished edge, which a diode laser cannot do.
Not to be confused
The CO₂ laser is not a fibre laser: its light has ten times the wavelength and is not suitable for marking bare metal without marking spray.
Frequently asked questions
Can a CO₂ laser cut metal?
Not with hobby and workshop devices of 40 to 150 W. Only industrial CO₂ systems with several kilowatts or fibre lasers cut metal.
Why does a CO₂ laser need water cooling?
A large part of the electrical energy turns into heat in the tube. Without cooling, power drops and the tube can crack or age quickly.