Abstract: The invention relates to a method and an apparatus for regulating an automatic treatment process. In order to ensure the desired quality of the treatment result and to improve it as compared with conventional methods, provision is made for a line of light (15) to be projected, by means of a light source (12) and first optics (13) arranged between the light source (12) and a workpiece (10) to be treated, onto a region of the workpiece (10) treated by means of a treatment head (24), for the line of light (15) to be projected onto a receiver arrangement (18) by second optics (17), and, by means of an evaluation circuit (22), for at least one treatment parameter of a treatment machine (23) to be regulated as a function of the comparison of an actual value of a parameter determined from the course of a profile with its desired value.