Application of digital holographic microinterferometer for microelements testing

Competitive trends to miniaturize Micro Electro Mechanical (and Optical) Systems (MEMS, MOEMS), electronic components and assemblies introduce unprecedented requirements concerning their design, manufacturing and testing. The paper presents a concept of digital holographic microinterferometrer (DHMI) for microelement deformation testing. DHMI may provide all components of the displacement vector and work with reflecting and scattering surfaces of object under test. For numerical reconstruction of digitally stored holograms a new method based on the sphere transformation theory is applied. It significantly simplifies the analyses in comparison with a conventional method directly based on the Fresnel approach. The algorithms proposed enable fast and high accuracy measurements. In the paper the practical realisation of DHMI is presented. The measurement methodology is shown on the example of deformation testing of pressure loaded silicon micromembranes. The results were used for verification of micromembrane modeling by FEM.