| 摘要 |
PURPOSE:To measure the real focusing position under overall conditions at the time of the actual laser beam machining including the influence of the thermal strain of a lens by measuring the photodetected laser beam energy taken out by a selective taking-out part with the fine width of a chopper disk to grasp its maximum point accurately. CONSTITUTION:The chopper disk 3 provided with a fine slit 4 with the prescribed length (l) and the fine width (w) in the radial direction is prepared. Then, with an inclination by an angle theta from the orthogonal surface to a projecting optical axis of a laser beam, the chopper disk 3 is rotated with the prescribed number of rotations and the laser beam 1 at the time of the actual laser beam machining including the peak power such as the cutting, welding, etc., and the various conditions is projected on the chopper disk 3. The laser beam 1 passed through the slit 4 in the rotating chopper disk 3 is made incident on a sensor 6. Then, the position of a condensing lens 2 is moved vertically and the time when the integral energy of the passed output becomes maximum is the time when the focusing position is on the surface of the chopper disk and the distance between this point and the condensing lens 2 is the real focal distance. |
