Laser processing machines, such as laser cutting machine (LM), including a work table receiving workpiece (W), and work arm (1) with a laser cutting head (2). Laser cutting head (2) includes nozzle receiving device (7) and nozzle (D). Via nozzle (D) laser beam (11) may be directed onto work piece (W). Machine (LM) includes main drives moving work arm (1) and/or the laser cutting head (2) on X-Y-Z axes to process work piece (W), as well as an alignment unit to adjust laser beam (11). An adjusting station (3) includes receiving unit (31) fixing nozzle (D) and/or the nozzle receiving device (7) during centering of nozzle (D). The alignment unit has head element (5B) in laser cutting head (2). Head element (5B) receives nozzle (D) and/or the nozzle receiving device (7) and is slidable in X-Y directions, via the main drives. Head element (5B) may be fixed in a selected position, within the laser cutting head (2), via clamping device (12) releasable during nozzle centering at adjusting station (3).

The present disclosure relates to a method of determining a degree of fouling of a transmissive element of a laser processing machine (for example a protective window facing the workpiece). A laser beam is directed through the transmissive element. The method includes illuminating the transmissive element and taking an image, for example by a camera, of the illuminated transmissive element. The image represents pollution of the transmissive element. The image is analyzed for calculating an optical element fouling value that is a quantitative measure of the degree of fouling. In this calculation, the distance of the pollution to an intersection position of the laser beam propagation axis through the transmissive element is taken into account in that the pollution is given a weight by that depends on the distance to the intersection position.

A system (40) for processing a workpiece includes a support surface (88) for supporting a workpiece (44). The system (40) includes a processing tool (92) movable with respect to a processing path. The system (40) includes a sensor carriage (408) movable along a scan axis and having a light source (476, 515, 550, 586) located to emit a light beam at an angle to the scan axis onto a target surface of a workpiece (44), and a camera (484, 522, 558, 594) configured to record location data of the light beam on a target surface of a workpiece (44) as the sensor carriage (408) moves along the scan axis. The system (40) includes a control system for generating a three-dimensional point representation of a workpiece surface from the light beam location data, to control movement of the processing tool (92) based on the three-dimensional point representation of a workpiece (44).