Comprehensive study of moiré deflectometry based on diffraction order filtering of fringes

This paper presents a detailed investigation of the theory of moiré deflectometry through a comprehensive analysis of the higher-order diffraction of moiré fringes. We demonstrate the possibility of achieving always-high-resolution moiré fringes regardless of Ronchi grating positions and Talbot distance by filtering out the even diffraction orders of moiré fringes. Our theoretical studies lead to a comprehensive formulation of this technique, revealing the high potential of moiré deflectometry towards more precise measurement.