Laser processing head for processing a workpiece using a laser beam, comprises optics for focusing the laser beam emerging from an optical fiber on the workpiece, and a back-reflection sensor device with a radiation detector

摘要

The laser processing head for processing a workpiece (16) using a laser beam (18), comprises an optics (22, 28) for focusing the laser beam emerging from an optical fiber (14) on the workpiece, a back-reflection sensor device (12) with a radiation detector that is formed to determine the intensity of the laser beam back reflected from the workpiece, where the laser beam returns in the direction of the beam exit region of the optical fiber, and a control device, which is connected with the back-reflection sensor device and receives an intensity signal from the back-reflection sensor device. The laser processing head for processing a workpiece (16) using a laser beam (18), comprises an optics (22, 28) for focusing the laser beam emerging from an optical fiber (14) on the workpiece, a back-reflection sensor device (12) with a radiation detector that is formed to determine the intensity of the laser beam back reflected from the workpiece, where the laser beam returns in the direction of the beam exit region of the optical fiber, and a control device, which is connected with the back-reflection sensor device and receives an intensity signal from the back-reflection sensor device, where the control device formed to switchover the laser beam when the intensity exceeds a threshold value by the back reflection sensor device. The optics has collimator optics for collimating the laser beam emerging from the optical fiber, and focusing optics for focusing the collimated laser beam on the workpiece. A beam deflector or a beam splitter is arranged in the optical path of the laser beam between the collimator optics and the focusing optics in order to transmit a part from the laser beam to the workpiece in the direction of the beam exit region of the optical fiber back reflected and decoupled in the back reflection sensor device. The back-reflection sensor device has an optical filter, which is arranged before the radiation detector and is aligned on the wavelength of the laser beam, and a sensor device, which is arranged before the radiation detector so that a surface of the workpiece is projected on the beam exit region of the laser beam or on the sensor surface of the radiation detector. The optical filter is optical band pass filter, where the emission wavelength of the laser beam lies within the wave lengths passage area, whose half value width is 10 nm. An independent claim is included for a method for preventing damage of a fiber end of an optical fiber.