Abstract: A material-working device with working beams of a beam generator and with in-situ measurement of a working distance between the beam generator and a workpiece, the material-working device including a working laser; a laser scanner for the working laser, the laser scanner including a two-dimensional deflecting device with scanner mirrors and a variable refocusing device at varying working distances; and a sensor device including a spectrometer and at least one sensor light source, wherein measuring beams together scan a working area of the workpiece by the laser scanner and an objective lens while gathering the working distance, and the measuring beams of at least two of the light sources of the sensor device being linearly polarised and being coupled into a working beam path of the laser scanner of the material-working device by an optical coupling element in a collimated state with crossed polarisation directions.