3D-deformation analysis of micro-components using digital holography

Holographic Interferometry is widely used as a contactless method in experimental mechanics and non-destructive testing of materials and engineering components. But measuring the full 3D-deformation of the object's surface requires a complicated optical setup with at least three different illumination directions. Especially if micro-components with lateral extensions less than 10mm have to be examined the simple use of conventional holography becomes more and more a problem. Since high resolution CCD cameras are available for reasonable prices, digital holography can be used as a fast, easy and precise method for holographic interferometry. Compact and simple setups can be achieved by the use of fiber optics. Digital holography replaces the holographic plate by a CCD matrix. No additional magnifying optical components are needed to achieve lateral resolutions of about 5 mu m and deformation resolution of 15nm. Some experiments using four illumination direction in an optimized setup are presented. They show the 3D-deformation fields of small objects under a given load. The results are compared with computer simulations to receive material parameters.