We present a method for shape measurements, which is based on sampling the temporal coherence function of the light using a shear interferometer. In contrast to standard White Light Interferometry our method has low demands regarding the spatial coherence of the light and is robust with respect to exterior disturbances. We sample the coherency function of the light with the help of of a test object with steps of a couple of micrometers. Due to its common path principle the system is intrinsically vibration tolerant.
We demonstrate a digital holographic system for the fast inspection of the interior of micro parts, which is capable of working in an industrial environment. We investigate micro objects using Two-Wavelength-Contouring with a synthetic wavelength of approximately 90 μm. Special consideration is given to the mechanical robustness of the system. A compact Michelson-setup in front of the imaging optics increases the robustness for the measurement as the light paths of the object and reference have almost a common path. We also implement the Two-Frame Phase Shifting method for the recording of a complex wavefield. The use of two cameras for different polarized states for the object- and reference wave allows the recording of a complex wavefield in a single exposure per wavelength. The setup allows determining the shape of the interior surface of the object and faults such as scratches with a measurement uncertainty of approximately 5 μm.