Parasitic reflection elimination based on adaptive fringes via multi-scale parallel single-pixel imaging in phase measuring deflectometry

We introduce a method of adaptively modifying the screen display to eliminate the ghost fringes observed in deflectometry optical testing. First, the reflection areas on the screen for both front and rear surfaces are labeled by multi-scale Fourier parallel single-pixel imaging (MS-PSI). Then, high-quality front surface information will be obtained by casting the fringe patterns only on the labeled region rather than the whole screen with the traditional phase shift method. Finally, the remaining mixed signals, which are located in the center part, will be filtered out by classic spatial filtering. A plano-convex lens and a plano-concave lens are used to verify the experimental results of the method, and the final reconstruction accuracy reaches sub-microns.