In-line quality control using dimensional metrology of 3D metal parts printed by laser beam melting

We present an approach for quality control using dimensional metrology based on structured light applied to laser beam melting. This application serves as a model for in-line monitoring under adverse conditions such as elevated temperatures, stray light and thermal gradients in the process chamber making closed-loop control very ambitious. Nevertheless, we demonstrate the implementation of precise dimensional measurement of printed parts and powder deposition allowing in- or off-line process assessment. As data acquisition and processing must be fast, we investigate the so-called structure function to extract global or local parameters such as roughness or geometrical periodicities like waviness of the powder deposition.