Temporal Paul wavelet analysis for phase retrieval using shadow moiré technique

Abstract

Temporal Paul wavelet analysis for instantaneous phase extraction using shadow moiré technique is proposed. Unlike the Morlet wavelet, the Paul wavelet has less restriction on the adjustment of wavelet parameters and can provide an optimal time and frequency resolution for a particular application by selecting the proper parameters. The Paul wavelet is a complex wavelet and is suitable for processing the temporal intensity data obtained from the shadow moire technique for the phase retrieval. The proposed method can extract the phase information related to the state of the dynamic object at every instant in temporal domain. The phase information is associated to the displacement, three-dimensional (3D) surface-profile and the instantaneous state of the dynamic object. In addition, the instantaneous frequency of vibrating object can be obtained using the scale of the wavelet ridge by direct integration without temporal and spatial phase unwrapping. Thus the phase unwrapping error can be avoided. An experiment is conducted on the central loaded beam to demonstrate the validity of the proposed technique.