High Speed and High Precision Fs-laser Writing Using a Scanner with Large Numerical Aperture

Currently available high speed scanning systems based on galvo mirrors are equipped with objectives with small numerical apertures (NA < 0.2) which are not sufficient for most of the involume micro structuring processes. Whereas high precision air bearing translation stages are used with microscope objectives the speed is limited to approximately 100 mm/s. In order to overcome these limitations we integrated a galvo scanner into a system with large maximum scanning velocity (50 -400 mm/s), large numerical aperture (NA = 0.4-1.2), small focus size (0.6 -2.2 m), high precision (100 -400 nm) and computer controlled pre-compensation of spherical aberrations for involume focusing. Furthermore, we combined the scanning system with a computer controlled three axis translation stage to process large flat work pieces such as wafers up to 2 mm in thickness. As application of the scanner high speed direct writing of waveguides, markings, nano structures inside transparent materials as well as the high speed fabrication of 3D micro structures by in-volume selective laser etching are demonstrated.