Optically excited lasers – solid state lasers
They drill, cut, solder and weld, they engrave, clean and harden. We are talking about optically excited lasers – solid state lasers – where the active laser medium is crystalline.
In addition to gas lasers, which are the most prevalent carbon dioxide lasers, they are the most powerful laser types which are commercially available. These lasers can be used on materials such as glass, metal and plastic.
The solid state lasers – the optically excited lasers – are driven or "pumped" by light or infrared radiation. "Optically excited" actually means: to excite through radiation.
Optically excited lasers require a resonator, unless they are fibre lasers. As in other laser types, this consists of two mirrors between which the laser medium is placed. One mirror is a 100 per cent mirror, letting nothing through, while the other mirror is partially transparent.