Laser drilling is the oldest production technique using lasers. Nevertheless, the number of industrial applications is lying far behind of those of marking, cutting and welding. In cases when high accuracy is required, like for instance fuel injection nozzles, laser drilling could not fulfil the requirements, up to now.
The major problem is the relatively large amount of molten material produced when using common drilling lasers with pulse duration in the order of one millisecond. Shortening the pulse length down to the femtosecond range is widely proposed as a recipe to avoid melt, now. With shorter pulse length, however, complexity and price of laser systems increase significantly. From this the question arises, how short the pulses have to be to fulfil the requirements of a given application.
The paper summarizes drilling results obtained in the pulse regime from milliseconds to several hundreds of femtoseconds with fundamental and higher harmonic wavelengths. The investigated materials are steel and ceramics. With a new drilling procedure, the so called helical drilling, an unprecedented level of accuracy could be achieved in the nanosecond range.