Acousto optic modulated stroboscopic interferometer for comprehensive characterization of microstructure

• Main Author: Pai Screenivasan, Murali Manohar
• Format: Others
• Published: 2008
• Online Access: http://spectrum.library.concordia.ca/975843/1/MR40918.pdf; Pai Screenivasan, Murali Manohar <http://spectrum.library.concordia.ca/view/creators/Pai_Screenivasan=3AMurali_Manohar=3A=3A.html> (2008) Acousto optic modulated stroboscopic interferometer for comprehensive characterization of microstructure. Masters thesis, Concordia University.

Mechanical and electro-mechanical advancements to the nano-scale require comprehensive and systematic testing at the micro-scale in order to understand the underlying influences that define the micro/nano-device both from fabrication and operational points of view. In this regard, surface metrology measurements, as well as static and dynamic characteristics will become very important and need to be experimentally determined to describe the system fully. These integrated tests are difficult to be implemented at dimensions where interaction with the device can seriously impact the results obtained. Hence, a characterization method to obtain valid experimental information without interfering with the functionality of the device needs to be developed. In this work, a simple yet viable Acousto Optic Modulated Stroboscopic Interferometer (AOMSI) was developed using a frequency stabilized Continuous Wave (CW) laser together with an Acousto Optic Modulator for comprehensive mechanical characterization to obtain surface, static and dynamic properties of micro-scale structures. An optimized methodology for measurement was established and sensitivity analysis was conducted. Being a whole-field technique, unlike single point or scanning interferometers, AOMSI can provide details of surface properties as well as displacements due to static/dynamic loads and modal profiles. Experiments for surface profiling were carried out on a micro-mirror, along with 2D and 3D profile measurements. The ability of AOMSI to perform dynamic measurements was tested on Micro-Cantilevers and on AFM (Atomic Force Microscopy) cantilevers. The resolution of AOMSI was identified as 10nms. The results for static deflections, 1 st and 2 nd natural frequencies and mode shapes were found to be in good agreement with results from the developed theoretical model and manufacturers specifications. The approach is a novel approach to investigate the surface, static and dynamic behavior of microstructures using a single interferometer.