Scale-insensitive property of the temporal phase unwrapping in fringe profilometry applications

Abstract

Multi-frequency fringe projection profilometers that rely on temporal phase unwrapping require frequency selection that provides minor unwrapping errors with the smaller number of fringe patterns projected. The frequency selection presents a scale-insensitive property for 3D profilometers that is analysed and investigated by analytical, simulation and practical means in this work. This property has been tested in an experimental profilometer with a parallel axis optical configuration. The scale-insensitive performance of the temporal phase unwrapping is analysed over a range of Field of Views (FOVs). It is shown that after typical calibration procedures, the scaling constants of the temporal phase unwrapping remain constant for different scales of FOVs. Additionally, a theoretical relation among fringes period in emitters of Digital Light Processors (DLPs) and camera detectors for the fringe profilometer used is presented and confirmed by experimental results.