Beam delivery of femtosecond laser radiation by diffractive optical elements

A novel beam-forming and delivery technique for high-power laser beams for the generation of well-defined intensity distributions based on diffractive optical elements is reported. It will be shown that nonlinear beam distortions can be minimized by applying this technique in the field of femtosecond-laser-basedmicro-machining. As a concrete example, the production of high-quality holes in metallic workpieces at atmospheric pressure will be discussed.