Study of robustness of 2D fringe processing in coherence scanning interferometry for the characterization of a transparent polymer film

A robust characterization technique is required in the study of transparent polymer films which are complex and contain low contrast buried structures which are not easily observable using classical optical techniques. In coherence scanning interferometry (CSI), advanced signal processing has been developed in order to obtain higher quality cross sectional images as well as surface extraction and positional measurement of buried structures and interfaces. In this paper, we report a performance study of an improved XZ-scan technique in CSI using a 2D Teager Kaiser Energy Operator (2DTKEO) and the classical 2D Hilbert Transform (2DHT) in order to extract cross sectional tomographic scans within a transparent Mylar polymer film. Through simulation with a synthetic fringe signal, we demonstrate that the XZ-scan technique using a 2DTKEO and a 2DHT is more robust than the Z-scan technique using the well-known Five Sample Adaptive algorithm (FSA).