Refractive microlens structures with high-damage thresholds enable flexible beam shaping of high-power lasers

Abstract

High power and high energy laser sources are used in a large variety of industrial and scientific applications for material processing. The most common are welding, soldering, cutting, drilling, laser thermal annealing, micro-machining, ablation and micro-lithography. For optimised processes the most important laser sources today are: CO₂-lasers, Nd- YAG lasers, high-power diode lasers, excimer lasers or fiber lasers. Beside the right choice of the suitable laser source the right choice of high performance optics for generating the appropriate beam profile is of high importance for the applications. In many cases homogenous top-hat square or rectangular light fields as well as light lines are indispensable or add strong advantages to the application. This takes into account that gaussian shaped laser foci are not the ideal solution. Refractive micro-lenses and micro-lens arrays based on damage resistant materials are an efficient, compact and flexible solution to achieve adequate intensity distributions on the work piece. LIMO has a unique production technology based on computer-aided design that enables the manufacture of high-precision microlens arrays with free programmable surfaces. Thus, specific beam profiles with superior uniformity and efficiency can be generated. Compact beam shaper modules with prealigned optics have been developed. These modules simply have to be placed into the collimated input beam and the required intensity profile is generated at the target without any complicated alignment.