Measurement and control system for compensation of thermal effects in laser material processing

Thermal lensing leads to quality losses or, in extreme cases, to the abortion of the whole laser machining process. Here, we present a device for the inline measurement and compensation of the thermal focus shift. For the measurement, the diffraction pattern visible in the working plane created by an amplitude mask is used. By a readjustment of the position of the focusing element the thermal focal shift is compensated.