Determination of curvature and twist by digital shearography and wavelet transforms

• Main Authors: Tay, Cho Jui, Fu, Yu
• Other Authors: Temasek Laboratories
• Format: Article
• Language: English
• Published: 2010
• Subjects: DRNTU::Science::Physics::Optics and light
• Online Access: https://hdl.handle.net/10356/92036; http://hdl.handle.net/10220/6470
• Institution: Nanyang Technological University

A new technique based on digital shearography for determining the transient curvature and twist of a continuously deforming object from a series of speckle patterns is presented. The intensity variation of each pixel is analyzed along the time axis by using a complex Morlet wavelet transform. The absolute sign of the phase variation is determined by introduction of a temporal carrier when the speckle patterns are captured by a high-speed camera. A high-quality spatial distribution of the deflection derivative is extracted at any instant without the need for temporal or spatial phase unwrapping. The continuous Haar wavelet transform is subsequently processed as a differentiation operator to reconstruct the instantaneous curvature and twist of a continuously deforming object.