In-situ calibration of laser/galvo scanning system using dimensional reference artefacts

Laser powder bed fusion systems use a high-power laser, steered by two galvanometer (galvo) mirrors to scan a pattern on metal powder layers. Part geometric tolerances depend on the positioning accuracy of the laser/galvo system. This paper describes an in-situ calibration technique utilizing a camera coaxially aligned with the laser imaging a dimensional reference artefact. The laser positions are determined from the images captured by the camera while scanning the artefact. The measurement uncertainty is estimated using simulations. The in-situ calibration results are compared with the results obtained from the typical 'mark and measure' galvo calibration method.