Evaluation of the usage of a fiber optic low-coherence interferometer for surface profile measurements using Speckles analysis

The low-coherence interferometry is already an established technique for the high-resolution characterization of surface profiles. Its application in many industrial areas is however partially limited due to undesired effects in the interference pattern caused by different surface's roughness and form properties. The appearance of speckles in rough surfaces or the batwing-effect in high-precision topographies are examples of undesired influences. Another important limiting factor is the size and robustness of the metrological set-ups. The measurement of small cavities or the integration in production machines are therefore still a challenge. In this work the application of a fiber-optical low-coherence interferometer for the characterization of different surface profiles, as well as miniaturized and / or hard accessible features is presented. Focus will be given on the measurement of optical "uncooperative" surfaces, as rough and / or curved surfaces, for example in small cavities, using the analysis of the speckle phenomena.