Roland Gauch

Monitoring of the micro-drilling process by detection of laser-induced shock waves in air

Ablation and drilling utilising short pulsed solid state lasers are becoming increasingly important technologies for micro-machining, micro-structuring and micro-drilling. Ablative drilling using pulses shorter than 10 ps results in a high-precision processes and outstanding quality due to negligible heating of the workpiece and consequently a reduced formation of recast. The advantages of ultra-short pulsed lasers have thus proved to be attractive for industrial applications. Corresponding to this development, process monitoring and control turn out to be an essential requirement. Different aspects of the drilling process such as borehole depth, moment of break through and end of the process have to be monitored.In this paper we present a method that permits the determination of borehole depth as well as the detection of completion of desired channel morphology. The method utilizes the detection of shock waves generated during the interaction between laser beam and irradiated material. The results prove that the proposed method offers a potential for on-site diagnostics of the laser drilling process.Ablation and drilling utilising short pulsed solid state lasers are becoming increasingly important technologies for micro-machining, micro-structuring and micro-drilling. Ablative drilling using pulses shorter than 10 ps results in a high-precision processes and outstanding quality due to negligible heating of the workpiece and consequently a reduced formation of recast. The advantages of ultra-short pulsed lasers have thus proved to be attractive for industrial applications. Corresponding to this development, process monitoring and control turn out to be an essential requirement. Different aspects of the drilling process such as borehole depth, moment of break through and end of the process have to be monitored.In this paper we present a method that permits the determination of borehole depth as well as the detection of completion of desired channel morphology. The method utilizes the detection of shock waves generated during the interaction between laser beam and irradiated material. The results prove ...