Shadow moire profilometry by frequency sweeping

dA frequency-sweeping technique is proposed to measure the shape of objects with discontinuous height steps and/or spatially separated surfaces, which have been impossible to measure with conventional shadow moire topography. By controlling the rotation angle of the grating, spatiotemporal moire pat terns are produced with different contour intervals. The Fourier-transform technique has been applied to analyze these patterns and obtain the tempora l carrier frequency, to which the height distribution of the object is rela ted. Experimental results show the validity of this method. (C) 2001 Societ y of Photo-Optical Instrumentation Engineers.