Abstract: A method for calibrating a system that includes a build chamber to accommodate powder to be melted and an object to be produced and a height-adjustable build plate support in the build chamber to support a build plate. The system also includes a controllable optical unit comprising (1) a laser source, (2) a plurality of lenses, and (3) a mirror arrangement having a plurality of adjustably arranged mirrors. The controllable optical unit is configured to selectively direct a laser beam to a point in the build chamber at which to melt the powder. The method includes placing a scanning field plate on the build plate support, creating a plurality of optical reference points on the scanning field plate, generating a measuring grid on the scanning field plate by adjusting the mirrors using a calibration data set, and determining a relative positioning between the optical reference points and the measuring grid.