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Chapter 5:
Carrier Fringe Pattern Demodulation
In Chapters 2 and 3, the WFRn and WFFn are developed for exponential phase fields (T1 fringe patterns). In Chapter 4, wrapped phase maps (T2) are filtered and unwrapped. In this short chapter, demodulation of carrier fringe patterns (T3) is discussed. Due to the presence of a carrier frequency, the demodulation is not difficult. The Fourier transform (FT) is a widely used technique that converts a carrier fringe pattern to an EPF, from which phase can be obtained. The WFRn/WFFn can be used with or without the FT technique—these two options will be compared in Section 5.1. Fringe projection profilometry provides carrier fringe patterns containing profile information. They often come with undesired nonlinear intensities. In Section 5.2, The WFRn/WFFn and FT will again be compared when the nonlinearity occurs. We will focus on 2D fringe patterns and 2D transforms because they can be easily adapted to 1D and higher dimensions.
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