Highly accurate distance measurements with a fiber-optical interferometer

Today micro-system technology and the development of new MEMS are emerging rapidly. In order for this development to become a success in the long run, measurement systems have to ensure product quality. Most often, MEMS have to be tested by means of functionality or destructive tests. One reason for this is, that there are no suitable systems or sensing probes available which can be used for the measurement of quasi inaccessible criteria. A possible system configuration, that could help solve this challenge will be presented. This system combines a fiber-optical and miniaturized sensing probe with low-coherent interferometry, so absolute distance measurements with nanometer accuracy are possible. The specially developed sensing probe enables the system to be used for in-hole and in-cavity measurements below 1 mm. We furthermore present results of different test series to prove the system capability for MEMS-testing.