Interferometric metrology is a powerful tool and has many applications in research and industry. One technique uses the principle of path-length/phase shifting. The path length of the reference arm of the interferometer is adjusted till maximum fringe contrast is obtained. Interferometric height profilers of this kind can measure heights with a precision of up to 1nm. I am interested in developing interferometric systems for such measurements. For example, in MEMS sensors, where the deflection of a cantilever indicates the presence of a certain material.