The determination of material parameters of microcomponents using digital holography

Progresses in microsystem technology promise a lot of new applications in i ndustry and research. However, the increased complexity of the microsystems demand sensitive and robust measurement techniques. Fullfield and non inva sive methods are desirable to get access to spatially resolved material pro perties and parameters. This contribution describes a simple and fast interferometric method for th e analysis of shape and deformation of small objects by optical means. Thes e quantities together with a well defined loading of the components can be the starting point for the determination of material parameters like Poisso n-ratio. Young's modulus or the thermal expansion coefficient. Holographic interferometry and multiple wavelength contouring as well as multiple sourc e 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 measure d results that allows the numerical evaluation of the phase data to get abs olute shape and deformation information in Cartesian coordinates. Surfaces with holes, gaps and steps can be registered without any ambiguities. Digit al holography as the underlying holographic recording mechanism is extremel y 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 using silicon microbeams and an object from fine mechanics are described to show the great potential of these fast and robust measurement techniques with respect to the determination of material parameters. (C) 20 01 Elsevier Science Ltd. All rights reserved.