Advanced Concepts of using diode lasers in materials processing

In the last few years impressive advances in the development of high-power diode lasers (HPDL ́s) and their production technology have been achieved /1/. Output powers in the range up to 120 W out of one 10 mm diode laser bar have been reported /2,8/ as well as rapidly declining prices. In the past most activities concerning application of HPDL ́s have been focused on the pumping of solid-state lasers, where the diodes are used as a substitute for flashlamps or arc-lamps in order to increase efficiency, beam quality, lifetime and reliability. Apart from these ”indirect” industrial applications the emission of HPDL ́s may be used directly for materials processing. In most cases of direct use of HPDL, techniques for beam shaping and combination have to be applied in order to match both the highly asymmetric beam and the output power of the diode laser bars to the requirements of the application. At present the most straightforward way to do this is based on incoherent superposition of diode laser beams. The principle as well as technical set-ups will be illustrated in chapter 2 along with a discussion of the physical limits of this technology with respect to output power and beam quality. Chapter 3 gives some examples of current industrial applications of such systems.