Combined 3D-shape and deformation analysis of small objects using coherent optical techniques on the basis of digital holography

Progresses in microsystem technology promise a lot of new applications in industry and research. However, the increased complexity of the microsystems demand sensitive and robust measurement techniques. Fullfield and non invasive methods are desirable to get access to spatially resolved material properties and parameters. This contribution describes a simple and fast interferometric method for the analysis of shape and deformation of small objects by optical means. These quantities together with a well defined loading of the components can be the starting point for a big variety of interesting material characteristics which can be evaluated by the use of physical models of the objects. Holographic interferometry and multiple wavelength contouring as well as multiple source point contouring are precise enough to fulfill the requests for precision and resolution in microsystem technology even on complex shaped structures with steps or gaps. A new adaptive, iterative algorithm is developed and applied to the measured results that allows the numerical evaluation of the phase data to get absolute shape and deformation information in Cartesian coordinates. Surfaces with holes, gaps and steps can be registered without any ambiguities. Digital holography as the underlying holographic recording mechanism is extremely suitable for small objects and lead to simple and compact setups in which the objects' shape as well as their deformation behavior can be recorded. Experiments are described to show the great potential of these fast and robust measurement techniques.