In this paper, we analyze theoretically the use of correlation statistical properties in the random speckle field, in the non-contact recording of free-response information of vibrating objects, and in terms of time-domain signals collected simultaneously at multiple points, and we use system identification techniques in the frequency and time domains to identify the dynamic parameters. The bending vibration of a miniature cantilever beam and the torsional vibration of a miniature shaft with 3-degrees of freedom are measured. The dynamic property parameters identified are in good agreement with the theoretical values. By the same process, the lower-order natural frequencies and modes of the bending arm of a dental drill are measured and analyzed.

by ASL