Frequency-multiplex Fourier transform profilometry: a single-shot three-dimensional shape measurement of objects with large height discontinuities and/or surface isolations

The performance of Fourier-transform profilometry is enhanced by a new technique that is based on spatial frequency multiplexing combined with the Gushov-Solodkin phase unwrapping algorithm. The technique permits the three-dimensional shape measurement of objects that have discontinuous height steps and/or spatially isolated surfaces, which has not been possible by conventional Fourier-transform profilometry. An important feature of the technique is that it requires only a single fringe pattern; the single-shot recording makes possible the instantaneous three-dimensional shape measurement of discontinuous objects in fast motion. Experimental results are presented that demonstrate the validity of the principle. Key words: Phase unwrapping, profilometry, fringe analysis, optical metrology, heterodyne interferometry, Fourier transform.