Drift compensation technique of an area-varying capacitive displacement sensor for nanometer resolution

Since a widely-used gap variation type capacitive displacement sensor has small measurable range, an area-variation type capacitive displacement sensor was proposed for a larger measurable range. The area-variation type sensors, however, may show considerably large drifts in its out signals. The drift is thought to be caused by such parameters as stage alignment errors, thermal effects, external electric waves, etc. In this study, the drift is successfully reduced without loss in SNR (signal to noise ratio) by adopting two sets of electrodes.