For the realization of a laser-based manufacturing process, a “machine tool” is required which, in addition to the laser beam as the actual “optical tool”, requires a set of integrated components capable of manipulating the laser beam and the workpiece to carry out the desired process. The design of this equipment – the laser unit in Figure 1.1 –, which is also referred to as a “processing station”, “processing system”, or “processing plant”, must be adapted to the requirements of both the laser process and the specific application. For example, a laboratory or prototype operation will have different criteria than the ones relevant for engineering production, and the requirements for applications such as the welding of car bodies differ from those for the production of high-precision bores.