Hybrid Beam Shapers - Compound Design and Integrated Fabrication Techniques

Progress in the development of micro machining techniques allows the fabrication of a wide range of surface shapes at highest precision. However, every fabrication approach is restricted either by technological or economical boundary conditions. Thus the realization of complex optical surfaces composed of features from several microns to millimeters demands the combination of different machining modes. In our contribution we present a highly flexible and precise integrated machining of a reflective hybrid freeform beam shaper offering beam deflection, transformation and splitting capabilities. For this purpose we combined ultra-precision micro milling, to realize the reflective basic shape, and direct ps-laser ablation, to produce exactly aligned diffractive structures. In combination with a compound optical design procedure this allows for integrating numerous optical functionalities within fewer surfaces. This means a huge potential for miniaturization and the reduction of alignment sensitivity of optical systems. The suitability of the applied fabrication and design approach is verified by experimental investigations of the optical performance and profilometric measurements.