3D profilometry for turbine blade shape profiling

Abstract

Non contact 3D measurement techniques such as those based on Fringe Projection Profilometry are increasingly popular as they offer a quick and accurate method to obtain the profile of critical components. This technique requires the projection of pre-designed sinusoidal fringe patterns on to the object, where they will appear to be deformed due to the height variation on the object. The fringe patterns captured by a CCD camera are then analyzed with phase shifting method to retrieve the wrapped phase map. This is followed by temporal phase unwrapping to obtain the unwrapped phase map, which is then paired with calibration parameters to obtain the final 3D result. The 3D data of the inspected component are then compared with those of a standard sample to detect any irregularities if any. Fringe Projection Profilometry has been suggested as a feasible method for 3D optical non-destructive testing for industry applications.