15 May 2014 Dual-laser vibrometry: Elimination or extraction of pseudo vibration
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This paper investigates the principal idea of a method using two identical laser vibrometers to eliminate pseudo vibrations, occurring as structured noise in laser-vibrometer measurements of angular velocity of a rotating object. The two vibrometers monitor the same surface path on the rotating object, but are separated by a well specified angle. Thus, they are aligned in such a way that they observe the same speckle patterns, but with a relatively time lag given by the angular separation of the vibrometers and the angular velocity of the object. However, any physical variations in angular velocity of the object occur simultaneously at the two vibrometers. Knowing the angular separation between the vibrometers, simple trigonometry can be used to eliminate the pseudo vibrations. These vibrometers are based on cameras, therefore the experiments demonstrate the principle of the method only, and no real time measurements are obtained here.
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M. L. Jakobsen, M. L. Jakobsen, M. J. Bækbo, M. J. Bækbo, S. G. Hanson, S. G. Hanson, "Dual-laser vibrometry: Elimination or extraction of pseudo vibration", Proc. SPIE 9141, Optical Sensing and Detection III, 91411G (15 May 2014); doi: 10.1117/12.2052176; https://doi.org/10.1117/12.2052176

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