Novel System Technology for Trepanning a Laser Beam at Arbitrary Developments of Angle of Incidence and Lateral Focus Position

In laser materials processing, trepanning optics are used to fabricate laser drilled holes of high aspect ratios (> 10) and controllable drill-hole conicity. However, trepanning optics available up to today are limited to circular trepanning geometries. Thus, only circular holes with drill-hole wall angles of rotational symmetry are feasible. Within this paper we will present a novel trepanning optic based on two piezo-actuatoric tip/tilt mirrors, being first of its kind, which allows arbitrary developments of propagation angle and lateral position of the laser beam, both being independent of each other. Consequently, the novel trepanning optic allows arbitrary drill-hole geometries such as circular, elliptical, rectangular etc. At the same time the drill-hole wall angle may be varied freely. Thus, asymmetric drill-hole wall angles are feasible such as tilt of the drill hole or wobbling of the drill-hole wall angle for instance. Demonstrative drill-holes of different shapes produced with an ultrashort pulsed laser prove the flexibility of the trepanning optic presented.