Several optical methods have been developed for the measurement of in-plane vibration of microscopic objects. However most of them need a scattering surface or a specific surface structuring. A low cost method which has not these limitations is optical stroboscopic microscopy combined with image processing by optical flow techniques. Previous works have shown that a nanometric sensitivity can be obtained. In this paper, we investigated several subpixel image processing methods for in-plane vibration measurements of MEMS by this technique. Emphasis was put on whole displacement field measurements and on fast algorithms able to process a large sequence of images without the need of a multi-resolution approach to get local vibration amplitudes. It is notably shown that use of spatiotemporal regularity between images is an efficient way to reduce noise and that a resolution in the 0.01 - 0.03 pixel range can be achieved. Results are applied to in-plane vibration local measurements in two perpendicular directions at video rate as well as to full-field mapping of in-plane vibration mode of electrostatically actuated MEMS devices in SOI technology.

Date Published: 3 October 2003
PDF: 11 pages
Proc. SPIE 5145, Microsystems Engineering: Metrology and Inspection III, (3 October 2003); doi: 10.1117/12.500141

Published in SPIE Proceedings Vol. 5145:
Microsystems Engineering: Metrology and Inspection III
Christophe Gorecki, Editor(s)