ABSTRACT
This chapter focuses on a common phenomenon: the granularity observed whenever a rough surface is illuminated with coherent light. It describes how speckle metrology can be modified and adapted in order to serve investigations in the microscopic world, i.e., for structural dimensions from a few millimeters to several micrometers. The speckle pattern is a unique fingerprint of the object surface under certain illumination and imaging conditions. The speckle pattern in the image plane is a 2-D cut through a 3-D speckle intensity structure. The chapter examines the basic concepts of speckle metrology and provides a brief theoretical background of the methodology. It explores three major fields of application: nondestructive testing, analysis of microelectro-mechanical systems operation, and the determination of mechanical parameters of microsystems. Vibrating components are common in many microsystems; the corresponding natural frequencies are rather high, ranging from a couple of kilohertz up to several megahertz, due to the small structural dimensions.
