Springer Science and Business Media LLC

A mechanically resonant torsional spring scanner was previously designed for light dispersion application. However, the effects of mountings and pressure variation on the damping characteristic of the scanner were not well studied. In this study, the damping characteristics of the linear optical scanner with torsional spring mechanism are investigated with a mathematical model and various experiments. To examine the scanner’s free response profile when the resonance frequency and damping ratio were varied, a damping model was established based on experimental results. Several experiments were performed to investigate the damping characteristics when environmental pressure and scanner mounting are changed. The scanner mountings consist of rigid mounting, spring demounting, and the use of various dampers. In general, the scanner damping was shown to be greater at higher atmospheric pressures when the scanner was mounted on a foam damper.

To acquire quantitative material stiffnesses from the highly dispersive flexural plate mode, it is extremely important to accurately measure both velocity and frequency. Since the frequency content of the signal is highly dependent on the response of the transducer, one cannot simply assume that the frequency of the electrical input drive pulse is the same as the frequency of the transmitted and received signals. As has been shown, making this assumption can result in significant errors in the stiffness. A simple method to estimate the actual frequency content of the received signal from an inversion of the period was demonstrated. By using this method, the stiffness results have been shown to be very accurate as well as independent of the type of transducer used.