Method and apparatus for adjusting the focal position of a laser beam directed at a workpiece

A method of adjusting the focal position of a workpiece (19) directed laser beam (18) consisting of a processing head (11) with a therein arranged displaceably focusing optics (12) for the laser beam (18) emerges, in which - the distance (d) between the processing head (11) and the workpiece (19) is kept constant, - inside the Berarbeitungskopfes (11) with at least one radiation detector (22) between the laser beam (18) and the workpiece (19) coming radiation is detected, the proportion of a region of an interaction zone (21) which reflects in the processing head (11), in particular diffusely reflected, and - the focusing optics (12) is moved so that a corresponding one of the detected radiation signal (S) takes a largest value.