In Situ Diagnostic for Multi Pulse Processing of Transparent Materials

Confined energy deposition by focused ultrashort pulses within the bulk of transparent materials enables the usage of glass as engineering material of the 21
^st
century. In this framework multi pulse effects such as incubation or heat accumulation were found as beneficial, e.g. for selective etching or local heating and welding purposes and thus giving rise for versatile applications in the field of microfluidics, medical industry or consumer electronics [1,2]. However, the process-specific overlap implies limited translation speed using the direct writing approach and thus also the throughput cannot be scaled indefinitely. Even more, nowadays lasers come up with continuous increasing average power which in the first instance cannot directly be used for processing. One major issue for that is induced (transient) stress that typically scales with the applied average power leading to crack formation when using the same processing strategy [3]. In addition, local melting by continuous pulse trains can induce disadvantageous stress distribution.