The invention relates to an arrangement (1) for the on-line monitoring of the quality of a laser process exerted on a workpiece (3), comprising a laser source transmitting a laser beam (4) to the workpiece (3), the thermal process of the laser beam (4) causing emission of electromagnetical radiation (7) from the process zone on the workpiece (3); a heat detection camera (8) for detecting the electromagnetical radiation emitted from the process zone of the workpiece (3), wherein the arrangement (1) is provided with a tilted non-focussing mirror (5) such that the laser beam (4) which is transmitted by the laser source is let through the tilted non-focussing mirror (5) towards the working piece (3), and the electromagnetical radiation (7) emitted from the process zone on the workpiece (3) is reflected by the tilted non-focussing mirror (5) towards the heat detection camera (8). The invention further relates to a method using such an arrangement (1).