LASER PROCESSING METHOD FOR ADJUSTING FOCAL SHIFT ACCORDING TO KIND AND LEVEL OF CONTAMINATION IN EXTERNAL OPTICAL SYSTEM BEFORE LASER PROCESSING

摘要

To adjust focal shift according to the kind and the level of contamination in an external optical system before laser processing.SOLUTION: A laser processing method includes steps of: before laser processing, calculating a focus movement amount based on a first measurement value which is an energy amount of a laser beam passing through a small diameter hole S, measured in the state where an external optical system 12 is warmed, and on a first reference value (database D1) determined beforehand corresponding to the kind of contamination in the external optical system 12 relative to the first measurement value; and correcting a focal position at a laser processing time based on the calculated focus movement amount.SELECTED DRAWING: Figure 5