Today, solid-state lasers commercially are available in the power range upto 3 - 4 kW. This permits to perform surface treatment with high efficiency. The main advantages in transformation hardening with Nd:YAG-lasers are the elevated absorptivity of 1.06 μm radiation for steel and the high transmission in glass, enabling to make use of the beneficial properties of glass (in comparison with material suitable for CO2-lasers) for beam guiding and shaping. As the intensity distribution in the laser spot at the workpiece surface determines the temperature cycle of the treated material, the beam shaping of laser radiation has an important influence on the processing result.

In this paper different beam shaping systems for Nd:YAG-lasers will be presented. The proposed systems use multi-reflexions (step-index-fiber, kaleidoscope), splitting and joining of beam parts (axicon, facet integrator), beam combining and imaging (telescope) to create intensity profiles at the workpiece adapted to the processing task. A special optic for hardening the inner sides of narrow bores will be demonstrated as well. This optical system includes pyrometric control of the temperature in the irradiated area allowing the quality of the process to be ensured by a closed loop control.

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© 1995 Laser Institute of America.
1995
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