4 April 1994 Studies of Fourier transform profilometry
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Abstract
This paper presents a comparison between two different optical geometries used in Fourier Transform Profilometry (FTP); crossed- optical-axes geometry and parallel-optical-axes geometry. A mathematical proof is presented to demonstrate that parallel- optical-axes geometry can provide a wider range of measurement than crossed-optical-axes geometry. The FTP method decodes the 3- D shape information from the phase information stored in a 2-D image of the object onto which Ronchi grating is projected. The phase information can be separated from the image signal by two methods; the phase subtraction method and the spectrum shift method. An experimental comparison between two phase extraction methods is presented. The results show that the phase subtraction method is less susceptible to nonlinearity of recording media and systematic optical geometry error. On the other hand, the spectrum shift method is faster in terms of computing time and noise immune. The experimental comparison also demonstrates a noise immune phase unwrapping strategy, based on a minimum spanning tree approach, to form a contiguous map of the object surface.
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Ping-Hai Chan, Ping-Hai Chan, Peter John Bryanston-Cross, Peter John Bryanston-Cross, John T. Judge, John T. Judge, } "Studies of Fourier transform profilometry", Proc. SPIE 2178, Visual Data Exploration and Analysis, (4 April 1994); doi: 10.1117/12.172067; https://doi.org/10.1117/12.172067
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