| 摘要 |
PURPOSE:To keep the focus beam diameter constantly always irrespective of the position of a work head and to increase the work accuracy by making the cut width of the body to be worked constant by correcting the focus position of a focusing lens with the position signal of the work head. CONSTITUTION:The position of a work head 13 is detected by the linear encoder 25, 27, 29 in the direction X, Y and Z, the position signal thereof is inputted into the correction value setting device 31 at the focus position of a focusing lens 15 and the correction value of the focusing lens corresponding to the optical path length is outputted. By this correction value thereof the step motor of the focus position control device fitted to the inner part of the head 13 is operated, the focusing lens 15 is moved by the prescribed quantity in the prescribed direction and the diameter of the focus beam is controlled so as to make it always constant. |
