Moiré deflectometry with pure sinusoidal gratings

The effect of using a sinusoidal grating instead of a Ronchi ruling as the object grating in moiré deflectometry is discussed and demonstrated. The method reduces the diffraction blur, which hinders the use of the conventional moiré deflectometer for objects of locally varying focal lengths. The technique combines most of the advantages of moiré deflectometry and shearing interferometry.