Optimized Temperature Distribution for Laser Hardening with Freeform Mirrors

Laser beam shaping by the usage of freeform mirrors for laser hardening is a known technology which has been used for CO2-Lasers. Nevertheless, due to developments in manufacturing technologies and computer simulation the industrial relevance has increased recently. By now, it is possible to manufacture freeform mirrors precise enough for the diode laser wavelength. With these mirrors, complex intensity distributions can be generated. Combined with a solution of the Inverse Heat Conduction Problem, the temperature distribution in the process zone can be designed according to the process necessities. This study will compare the results of three different profiles which were designed to optimize the process. The first optic generates a rectangular isothermal profile. The second is a rectangle with a reduction of temperature in the direction of the movement to avoid grain growth. The third is optimized to increase the desired compressive residual stresses.