Certain types of YAGs are known as fiber lasers. A YAG (Yttrium Aluminium Garnet, a synthetic crystal material) laser tends to be used for marking harder materials. It won’t mark cardboard but is ideal for copper, engineering plastics and other materials that a CO2 laser cannot handle. Indeed, all laser cutting of metals is by a YAG device. Consequently, YAG lasers are commonly used in the aerospace, automotive and direct part marking industries where nothing else will do the job and where the high price (typically over £20,000 per installation) can be justified.

The YAG operates on a different frequency (1.06 microns) and needs an external diode pack to generate the light. It also needs cooling, normally water cooling, because the large units in particular can run very hot. The cooling equipment has to be fully integrated with the laser since operating it without cooling would not be advisable.

Safety guarding of YAG lasers is a serious issue. These are the same type of lasers as those used for eye surgery and so foolproof guards are essential to prevent accidents.