Exploration of the sequence for selecting experimental parameters for moiré deflectometry

The selection of certain key parameters is crucial to the experimental results in moiré deflectometry. This paper begins with the scalar diffraction theory to analyze the relationships between parameters, such as the dependence of moiré fringe spacing, fringe displacement, and relative fringe displacement on factors including grating constant, grating separation, grating line orientation angle, and diffraction order. Subsequently, several sets of experiments are conducted to verify the theoretical analysis results. Finally, based on both theoretical and experimental findings, the sequence for selecting various experimental parameters for four scenarios in moiré deflectometry is proposed. Concretely speaking, the grating constant, appropriate order, and grating line orientation angle should be first chosen based on the fringe spacing, and then, a suitable grating separation could be selected according to the magnitude of the fringe displacement. In summary, this research provides a valuable reference for further expanding the application of moiré deflectometry.