During the last years a new laser beam scanning system for heat treatment of metals with high power diode lasers was developed. The new external scanning optics is an optional tool, that can be used with common standard high power diode lasers (focal distance e 300 mm). It works with high power diode lasers in the multi-kilowatt range up to 5 kilowatt laser power. The new system opens the door to a wide field of applications, that were not possible before. Heat treatment of metal surfaces with a track width of more than 50 mm at once is one of the capabilities. Furthermore different approaches were gone to make the handling of the system more easier for the user. Real-time temperature control with cycle times in the range of microseconds ensures a reproducible hardening result even for complex 3D- shaped parts with difficult heat flow conditions. The latest status of the developments and examples are presented.