Semi-automated measurement of injection nozzles using fiber-optical low-coherence interferometry

The roundness measurement of boreholes with diameters less than 500 microns is a challenge that cannot be addressed with conventional metrology such as tactile measurement. This paper presents a setup for semi-automated positioning and roundness measurement of boreholes with diameters down to 160 microns using fiber-optical probes and low-coherence interferometry. The results contribute to sophisticated nozzle design and testing of final parts such as common-rail diesel injection nozzles.