摘要： The laser cutting of 60-mm-thick stainless steel using a 6-kW ?ber laser was performed to investigate the e?ect of the geometric nozzle con?guration on the operating tolerance of the stand-o? distance. The stand-o? distance is the distance between the nozzle tip and the top surface of the steel plate. Two types of nozzles—a subsonic nozzle with a convergent geometry and a supersonic nozzle with a convergent-divergent geometry—were used to comparatively evaluate the ?ow behavior through interferometric analysis. A laser cutting experiment was conducted in accordance with the interferometric analysis, focusing on the stand-o? distance variation. The stand-o? distance was varied from 1 to 60 mm in consideration of the melt-removal capability of the applied cutting nozzles. The throat diameters of the nozzles were 2 and 3 mm. According to the results, the supersonic nozzle has a better operating tolerance of the stand-o? distance for the laser cutting of 60-mm-thick stainless steel.