ABSTRACT
This chapter provides the analysis of the optical damage of metals to surface melting, vaporisation and plasma ignition. It reviews the main technologies in use for manufacturing laser mirrors. The homogeneity of a surface layer of metal, of sufficient thickness, prior to diamond turning, can be improved in several ways. One method is surface melting under the action of a scanning electron beam, allowing for a significant reduction in the metal porosity. All mirror surfaces, no matter how pure the metal base, and regardless of the sophistication of the manufacturing technology, become dirty in contact with the environment. Specific to multipulse irradiation is the fact that macroscopical damage of the surface is always preceded by microdamage—characterised by the formation and development of microcracks. The vaporisation damage causes the formation of a crater in the zone of action of the laser radiation.
