A closer look at dynamic speckles and the use of their fine-structure for object measurements

The possibility to “dress up” the speckles and thereby providing them with a fine structure will be discussed. As these speckles arise from scattering off solid targets, the dynamics of the speckles and their inherent fine structure might vary, providing information on different aspects of the surface displacement. This is achieved by illuminating the object with structured light, and observing the speckle field as it passes an optical system. In this way, simultaneous measurement of displacement (e.g. 2-D) and rotation can be performed. The application of this concept with a system based on spatial filtering velocimetry and ordinary speckle correlation will be discussed.