Ring focus lens for the circumferential welding of rotationally symmetrical workpieces

A ring focus optics for machining rotationally symmetrical or nearly rotationally symmetrical workpieces by an annular laser beam includes a conical mirror configured to deflect the annular laser beam radially inward or outward onto a circumference of at least one workpiece, a rotational axis of which is aligned collinear to an optical axis of the ring focus optics. The ring focus optics further includes a holding/centering device surrounded by the annular laser beam and fastened on the housing of the ring focus optics. The holding/centering device is configured to axially fix the at least one workpiece and/or to radially center the at least one workpiece with respect to the optical axis.