Study of a Small-sized Ultrasonic Probe

This paper presents the design and testing of a small-sized ultrasonic probe that is able to measure non destructively a micro-part surface form with sub micro Newton measuring force. A force sensor installed in the probe has a Ni-Cr stylus of 3 mm length that is axially vibrated by a bulk-PZT at longitudinal resonant frequency. At the end of the stylus a glass tip ball of 30 μm diameter is mounted. The stylus aspect ratio of 100 is around the highest level available. An algorithm for autonomous profiling measurement using output-signal of the ultrasonic probe is presented as well as measurement results of a micrometer sized hole and gear surface form. So far measurement uncertainty is in the micrometer region but it is expected that this can be reduced.