Normalized Hilbert Huang Transform-NHHT Applied to Phase Extraction in Wavelet Domain

ABSTRACT

The purpose of the present work is the use of the Normalized Hilbert-Huang Transform (NHHT) to generate an exact quadrature fringe pattern. The NHHT has helped to overcome many of the difficulties of the regular Hilbert transform. In the wavelet domain, the phase evaluation method needs a fringe pattern with a spatial carrier. It is possible to provide synthetically a modulated fringe pattern by combining a computer generated grating with the pattern and its quadrature. Then, using continuous wavelet transform decomposition, it is easy to calculate the phase gradient computed from maximums scales and provide by simple integration the phase map coded in the fringe pattern. This method leads directly to phase distribution from a single pattern avoiding the complex step of phase unwrapping.

Keywords:

Normalized Hilbert Huang Transform (NHHT), Empirical Mode Decomposition (EMD), Phase Evaluation Methods, Continuous Wavelet Transform (CWT).