• model updating
• vibrometer
• continuous scanning
• misalignemnt
• laser

This thesis has been developed at Imperial College, London. The aim is the definition of a model that evaluates the alignment of the components of a laser Doppler continuous scanning vibrometer in order to assess the tracking errors of the laser spot. A series of measurement tests on the system has been carried out to highlight the effect of misalignment of the system components on the measurement output. A geometrical model of the laser tracking error related to the orientation parameters of the system has been realised: the model has been checked with a CAD simulation and measurement tests on the structure. Moreover a sensitivity analysis has been performed to weight the tolerance limits for the alignment of the system components. The ideal path and the misaligned path are simulated over the finite elements model and compared using the &#8220Modal Assurance Criterion&#8221 in order to state a threshold for the measurement accuracy that considers also the dynamic behaviour of the measured structure.