Typical marking lasers come in three types – carbon dioxide (CO2), YAG or Fibre.
The most basic form of a CO2 laser consists of a gas filled tube discharge tube with a reflector at one end, and an output coupler (a partially reflecting mirror) at the output end. CO2 lasers have a high wavelength (operating in the infrared range) which makes them a poor choice for metal marking applications because the laser radiation is often reflected by the target material.
YAG and fibre lasers have shorter wavelengths which not only provide better marking resolution, but are also easily absorbed by metal.
YAG lasers (also called flash lamp or lamp-pumped lasers) use a bulb lamp as a pumping mechanism and yttrium aluminium garnet (YAG) synthetic crystal as the gain medium. They are becoming less popular because the bulbs have a short life and the lasers are inefficient – they generate a lot of heat and therefore require a liquid coolant.
Solid state fibre lasers have become the industry standard for reliable, high quality marking. The laser source is sealed, preventing dust and particle contamination. This also enables longer distances between the control unit and the marking head, allowing the laser source to be situated remotely from the point of use. Furthermore, it reduces leakage, resulting in greater efficiency.
Overall, the fibre laser is cheaper to run and has fewer replacement parts than the YAG laser. The fibre laser is air-cooled, which makes it more compact and easier to integrate into existing systems and processes.