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In order to improve the safety, lifetime, and energy efficiency of turbomachines, the dynamic behavior of the rotor has to be analyzed. Blade vibrations have to be monitored during operation to optimize the rotor design and to validate numerical models. However, measuring the vibration amplitude and frequency of the blades is a challenging task for metrology, since the blades to be measured are rotating quickly, and noncontact measurements are demanded. To solve this problem, we present a measurement system consisting of four laser Doppler sensors that have been mounted around the circumference of the rotor. These sensors measure simultaneously and contactlessly the in-plane velocity and the out-of-plane position of laterally moving objects. By analyzing the variation of the blade tip velocities, the vibration amplitude and frequency of the blades were estimated. Blade vibration measurements down to amplitudes of only 20 μm in tangential direction have been carried out. We achieved a standard uncertainty of approximately 400 nm for these experiments.

For in-process shape monitoring of rotating objects such as workpieces in a turning machine, contactless and compact sensors with high temporal resolution are necessary. For this challenging task, we developed a miniaturized and robust nonincremental interferometric fiber-optical distance sensor with dimensions of only 30 × 40 × 90 mm 3 , which enables attaching the sensor head directly to the mount of a turning tool bit. We present the results of in-process 3-D shape measurements of turning parts at a metal working lathe. To proof the accuracy of the measurement results, comparative measurements with tactile and optical sensors were performed. A maximal deviation between the different measurement methods of 2.2 μm was achieved for the determination of the mean height of a radial step.

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