Three-dimensional laser ablation for functionalization of non-planar optical surfaces

Efficient laser beam shaping is one of the keys to achieve maximum process performance and to exploit new application fields for lasers. However, with increasingly more complex beam shaping tasks typically the challenges related to system size, weight and reliability scale up as more and more conventional optical components like spherical lenses, gratings, prisms etc. are involved. To overcome this traditional tradeoff several optical functions can be integrated in a single hybrid [1] [2] (reflective/diffractive, refractive/ diffractive [3]) optical freeform component enabling miniaturized [4] and robust beam shaping solutions. For the fabrication of these complex optical surfaces we use integrated fabrication techniques (section 2), which combine micromachining of continuous reflective freeform surfaces [5] and precise laser ablation of high frequency diffractive structures efficiently [6]. In this article we focus on the generation of high quality diffractive structures in copper using 3-dimensional picosecond laser ablation within a five-axis ultraprecision micromachining center (section 3).