SUMMARY

Laser Doppler Vibrometry (LDV) is a non-contact technique for sensing surface vibrations. Traditionally, LDV uses one or more fixed beams to measure the vibrational velocity of specific points and orientations. In order to measure an ang ular velocity at least two laser beams are required. Instead, this research proposes to develop a Continuous Scanning Laser Doppler Vibrometer technique (CSLDV), based on a single laser beam continuously sweeping the area of interest using a scanning mirror. Previous studies of the CSLDV technique were done with a slow scanning frequency (a few Hertz) to measure sinusoidally excited surface vibration of a structure at high frequency (> 100 Hz). Instead, this thesis develops new measurement methodology, while using a high scanning frequency (up to 200 Hz) to measure low frequency broadband vibrations (< 100 Hz).The idea of selecting the measurement of low frequency broadband vibration is that the natural vibration of human body is < 100 Hz. The second part investigates the CSLDV technique for longer scans (> 3 cm). These long scans will be used to act as an array of virtual transducers at multiple points along the scanning path of the single laser beam; thus yielding similar information obtained using an array of several real LDVs. Such systems will be used to monitor multiple degrees of freedom (MDOF) of human skeletal muscle vibrations. Either the natural or forced vibration of human muscles will be analyzed using these CSLDV techniques. Overall contributions of this work include: (1) the development of CSLDV sensing technique for broadband low frequency angular velocity measurements; (2) replacement of an array of vibration sensors by a single long scan of CSLDV; (3) application to sensing of human body vibrations (e.g. muscles and tendons).