Process of treating a workpiece using a liquid jet guided laser beam

A process for shaping a workpiece by ablating material using a liquid jet guided laser beam within a time frame, comprising the following steps:

• a. producing a liquid jet by a nozzle,
• b. impinging the liquid jet on a reference surface allocated to the workpiece, whereby an intersection of the liquid jet with the reference surface defines a liquid jet-footprint,
• c. effecting a displacement between the liquid jet and the reference surface, whereby the liquid jet-footprint evolves to a trace along a trajectory associated with the trace during the time frame, wherein the trace covers a trace-area, and
• d. irradiating the workpiece at least during part of the time frame with a laser beam coupled into the liquid jet to ablate material, and
• e. monitoring the remaining thickness of the workpiece while irradiating the workpiece with the laser beam;
• and
• wherein the trace has in sequence a first advance-segment, a return-segment and a second advance-segment, wherein
• i. the first advance-segment and the return-segment form a first and a second length-section of a first overlap area;
• ii. the return-segment and the second advance-segment form a first and a second length section of a second overlap area;
• iii. a common area of the first and the second overlap area are essentially superimposable with at least one of these two overlap areas;
• and
• iv. the trajectory is shifted in a reference surface coordinate direction, such that center lines of the different segments are displaced with respect with each other in such a way that the common area is part of the first advance-segment, of the return-segment and of the second advance-segment.