Moire deflectometry based on Fourier-transform analysis

An approach for moire deflectometry based on Fourier-transform analysis is described. Fourier-transform is used for analyzing and evaluating both infinite and finite moire deflectograms. Deflections in two orthogonal directions are integrated to reconstruct the tested surface. A least square fitting is used in finite moire deflectogram to eliminate declination error caused by inclination between two Ronchi grating lines. Results from experiments of aspheric surface measurement based on this approach have proved its effectiveness.