Improved accuracy in slope measurement and defect detection using Fourier fringe analysis

Abstract

This communication reports investigation undertaken towards measurement of slope and defect detection of bent plates (rectangular and circular) using moiré deflectometry in conjunction with Fourier transform technique. For slope mapping, specimen is illuminated by collimated light from a laser. The back reflected light from the front surface of the specimen is incident on a set of two gratings placed in tandem, resulting in the formation of laterally sheared interferograms. The interferograms are recorded using a CCD (charge coupled device) camera. Direct phase measurement using Fourier transform method has been used for measurement of slope and detection of defects. The experimental setup is simple and the slope measurement and detection of defects are undertaken successfully in each case. Experimental results conclusively establish the viability of the technique. Good accuracy and precision in measurement have been achieved. © 2017 Elsevier GmbH