Determining the degree of fouling of a transmissive element

Abstract

The present disclosure relates to a method of determining a degree of fouling of a transmissive element of a laser processing machine (for example a protective window facing the workpiece). A laser beam is directed through the transmissive element. The method includes illuminating the transmissive element and taking an image, for example by a camera, of the illuminated transmissive element. The image represents pollution of the transmissive element. The image is analyzed for calculating an optical element fouling value that is a quantitative measure of the degree of fouling. In this calculation, the distance of the pollution to an intersection position of the laser beam propagation axis through the transmissive element is taken into account in that the pollution is given a weight by that depends on the distance to the intersection position.

Dependencies are inferred from the claim text.