Coherence scanning interferometry with two polarization states

Abstract

Coherence scanning interferometry (CSI) is a precise and versatile method to measure the shape of objects with rough and smooth surface. However, this method requires a large amount of raw data. The demands on increasing measurement speed and camera resolution require to reduce the number of camera frames. We present an evaluation technique that allows a direct reconstruction of the interferograms envelope. An octadical wave plate is inserted into the reference arm of the interferometer. Thus two signals arise, each for one polarization state, that are shifted by 90 degrees to each other. From the two signals, a direct reconstruction of the interferograms envelope is possible.