Patent DE-102008060384-B3 (DE)
Title: Sensor system for monitoring laser machining process carried out on workpiece, comprises holding device, in which imaging optics is arranged, receiving device adjustable relative to imaging optics, light source module, and sensor module
Inventor: SPOERL GEORG
IPC: B23K26/08
Filed: 2008-12-03
Granted: 2010-04-01
Abstract: The sensor system (12) comprises a holding device (30), in which imaging optics (32) is arranged, a receiving device adjustable relative to the imaging optics, and a light source module, which is insertable in the receiving device at a predetermined position relative to the receiving device and comprises a light source with a first spatial-filter aperture that is represented through the imaging optics at a region in an area of an interaction zone between a laser beam (16) and a workpiece (14) to select a determined observation field in the interaction zone by adjusting the receiving device. The sensor system (12) comprises a holding device (30), in which imaging optics (32) is arranged, a receiving device, which is adjustable relative to the imaging optics, a light source module, which is insertable in the receiving device at a predetermined position relative to the receiving device and comprises a light source with a first spatial-filter aperture that is represented through the imaging optics at a region in an area of an interaction zone between a laser beam (16) and a workpiece (14) to select a determined observation field in the interaction zone by adjusting the receiving device, and a sensor module, which is insertable in the receiving device at a predetermined position relative to the receiving device and comprises a radiation-sensitive receiver with a second spatial-filter aperture, at which the selected determined observation field of the interaction zone between the laser beam and workpiece is represented through the imaging optics after insertion of the sensor module into the receiving device. The second spatial-filter aperture is fixedly arranged in the sensor module, so that the second spatial-filter aperture is arranged to the receiving device at a predetermined position after the insertion of the sensor module into the receiving device. The first spatial-filter aperture is fixedly arranged in the light module, so that a focal plane offset of the imaging optics is compensated based on the wavelength difference between the emitted light of the light source and the detected radiation by the radiation-sensitive receiver using a correspondingly different arrangement of the first spatial-filter aperture and the second spatial-filter aperture in an inserted state of the associated module. The first spatial-filter aperture of the light source module and the second spatial-filter aperture of the sensor module are a pinhole aperture or an inverse aperture for covering a central area. The radiation-sensitive receiver is a sensitive temperature sensor for infra-red radiation, and is a sensitive receiver for plasma radiation and for processing laser radiation. The sensor module has a further radiation-sensitive sensor, which is provided for the detection of radiation from the area of the interaction zone between the laser beam and the workpiece that lies in another wavelength region as the radiation detected by the radiation-sensitive receiver. The sensor module has a beam splitter in the observation beam path in direction to a further associated radiation sensor for coupling the radiation. An additional radiation sensor is a temperature sensor, or a sensitive sensor for plasma radiation and for processing laser radiation. The light source of the light source module is a laser light source, a light emitting diode, and cold light source with a fiber bundle. The receiving device and the imaging optics are adjustable to each other in direction to the optical axis to adjust an optical distance between the imaging optics and corresponding spatial-filter apertures of the light source module or the sensor module. The receiving device is relocatable vertical to the optical axis of the imaging optics in two directions linearly independent of each other to select the determined observation field in the interaction zone. The receiving device is designed, so that the sensor module and the light source module are clipped in the receiving device, where the sensor module and the light source module have a determined position relative to the receiving device in an engaged state. Independent claims are included for: (1) a sensor module; and (2) a method for selecting a determined observation field in an area of an interaction zone between a laser beam and a workpiece during a laser machining process.