The vibration analysis using a holographic interferometer is a very useful method for analyzing the dynamic characteristics of machine elements. However, there is the limitation that the method cannot measure large deformation. On the other hand, the method based on the moire topography has been proposed for solving this problem. However, there are also some problems peculiar to optical measurements. Because the moire method is based on the shape measurement, the displacement of an object cannot be directly measured. We should grasp the trajectories of movement of the measuring points in the case of measuring displacement of the vibrating object with large amplitude. Consequently, the nodal lines of the object at each mode can be drawn using the displacement. Then, the modal analysis can be performed against the vibration with large amplitude using the nodal lines. In this paper, a system that can measure the displacement of the vibrating object with large amplitude is proposed using the inverse-transformation for the central projection and estimating geometrically the trajectories of the corresponding points. The experiment results show that this method is useful for the measurement of the object's displacement and the vibration analysis in the case that the object is vibrated with large amplitude.

Date Published: 30 June 1998
PDF: 8 pages
Proc. SPIE 3478, Laser Interferometry IX: Techniques and Analysis, (30 June 1998); doi: 10.1117/12.312957

Published in SPIE Proceedings Vol. 3478:
Laser Interferometry IX: Techniques and Analysis
Malgorzata Kujawinska; Gordon M. Brown; Mitsuo Takeda, Editor(s)