Abstract: The invention refers to a method for determining the position of an elongated narrow object relative the surface of an obstructing disk-like body in front of said object and oriented at an angle thereto, by means of electromagnetic ionizing radiation, for guidance of the movement of an associated laser welding equipment For providing the carrying out of this method with high speed and greatest precision when manufacturing sandwich elements with conical or double-curved surface it is suggested according to the invention that from the side of the body remote from the object is directed, under approximate movement in the longitudinal direction of the object one precisely collimated radiation beam obliquely to the object under simultaneous scanning motion at right angles thereto, that the radiation back-scattered from the object is collected at the same side of the body and is brought to form a signal which is compared with memory-stored predetermined preference signals for the desired correct position of the obj