Robust data reduction of high spatial resolution optical vibration measurements

In several mechanical engineering applications high spatial resolution measurements are required. Adapted optical measurement instruments such as the laser scanning Doppler vibrometer (SLDV) and the electronic speckle pattern interferometer (ESPI) exist to perform this task. The result of this high spatial resolution measurement is that a large amount of data is available which has to be processed. In addition, care should be taken when processing the measurements, because locations with poor measurement quality typically exist. In this article a method will be developed to reduce the amount of measurements so that further processing is less time consuming. In addition, as a side effect of the data reduction method, poor quality measurements will be filtered and the overall SNR will improve. The method uses an iterative robust two-step spline approximation with an automatic model order determination procedure. The validation of the technique is performed both on scanning laser vibrometer measurements of a car door and a circuit board and on ESPI data.