Method of providing a machine readable marking on a substrate by laser ; Actuator with a part having such a marking

摘要

A method of providing a machine readable marking on a substrate (20) being a part of an actuator (15) is described, in which the marking includes at least first and second marks and the method including repeatedly firing a laser device so that at each of a plurality of row positions of a first area of the substrate (20), substrate material (20) is heated and displaced thus to provide a depression (d) in the surface of the substrate (20) at least martial surrounded by displaced material, the method including providing a plurality of rows of such depressions in the first area to form the first mark, repeatedly firing a laser device so that at each of a plurality of row positions of a second area of the substrate (20), substrate material (20) is heated and displaced thus to provide a depression in the surface of the substrate (20) at least partially surrounded by displaced material, the method including providing a plurality of rows of such depressions in the second area to form the second mark, and wherein each depression of the rows of depressions of the first and second marks has a depth determined from the general surface of the substrate (20) less than 4µm, and the height of the displaced material determined from the general surface of the substrate (20) is not greater than 4µm.