Patent DE-102010060958-A1 (DE)
Title: Laser processing apparatus comprises processing laser for generating processing laser beam to structural change, scan laser for generating scan laser beam, light detector, and reference structure for calibrating unit of control device
Inventor: PETSCHIK NORBERT
IPC: B23K26/02
Filed: 2010-12-02
Abstract: The laser processing apparatus comprises: a processing laser (3) for generating a processing laser beam (5) to a structural change modifying a workpiece incorporated into the laser processing apparatus, where the laser beam is movably guided in a laser-coordinate system associated by a processing beam-guiding device; a scan laser for generating a scan laser beam, which is movably guided by a scan beam-guiding device to the laser coordinate system; and a control device (25), which is connected with the processing beam-guiding device and the scan beam-guiding device. The laser processing apparatus comprises: a processing laser (3) for generating a processing laser beam (5) to a structural change modifying a workpiece (27) incorporated into the laser processing apparatus, where the laser beam is movably guided in a laser-coordinate system associated by a processing beam-guiding device; a scan laser for generating a scan laser beam, which is movably guided by a scan beam-guiding device to the laser-coordinate system; a control device (25), which is connected with the processing beam-guiding device and the scan beam-guiding device such that the scan laser beam is feasible by the scan beam-guiding device of the laser-coordinate system assigned to a transverse position over an outer peripheral edge of the workpiece incorporated into the laser processing apparatus; and a light detector (31), which is connected with the control device and arranged and adapted such that a brightness change of a secondary light in form of reflected and/or transmitted scan laser beam light is caused by passing the outer peripheral edge of the workpiece through the scan laser beam, and/or an edge scan-brightness profile encompassing the brightness change is detectable. The control device is further arranged such that it is based on the edge scan-brightness profile, which is detected by the light detector for passing over the position on the outer peripheral edge of the workpiece, where the positioning of the workpiece relative to the laser coordinate system is determinable. The associated position of the outer peripheral edge with respect to the laser coordinate system based on a transition between two constant brightness levels is determined. The control device is further arranged such that: the scan laser beam is guided to the position in both transverse directions passing over the outer peripheral edge of the workpiece and bidirectionally guided over the surface of the workpiece; and the transition between two constant brightness levels is recognized as a structure boundary into a surface scan-brightness profile. The processing laser and the scan laser are identical. The light detector is arranged such that: it forms on a scan laser beam-incident side of the workpiece incorporated into the laser processing apparatus, where the workpiece is turned away by the scan laser beam-incident side of the workpiece; and the brightness change of the secondary light is detected in form of the transmitted scan laser beam light. The light detector comprises a light-diffusing plate that is arranged such that it receives/diffuses the secondary light, and light sensors (35), which are arranged such that it detects an intensity of the secondary light received by the light-diffusing plate. The laser processing apparatus further comprises a reference structure for calibrating a unit of the control device and the positioning of the scan-laser beam achieved by the scan beam-guiding device. The control device is arranged such that a unit of the scan beam-guiding device of the scan laser beam is guided over the reference structure. The light detector is arranged such that the brightness change of the secondary light is reflected in form of the reference structure and/or is transmitted by the reference structure to the scan-laser beam-light, which is generated during the reference structure with the scan-laser beam, and/or a calibration-brightness profile encompassing the brightness change is detectable. The control device is further arranged such that it is calibrated by a unit of the calibration-brightness profile through the control device and the scan beam-guiding device obtaining the positioning of the scan-laser beam. Independent claims are included for: (1) a position-determining device for determining the positioning of a workpiece incorporated into a laser processing apparatus; and (2) a structure determining device for determining the structure of a surface of a workpiece incorporated into the laser processing apparatus.