Implementation of Coda Wave Interferometry Using Taylor Series Expansion

Coda waves are sensitive to small changes in scattering media, in which multiple scattering and repeatedly sampling occur due to the changes. Coda wave interferometry (CWI) is a technique to monitor the changes in media by comparing the coda waves before and after perturbation. Doublet technique and stretching technique are two commonly used approaches based on cross correlation when CWI analysis is performed. However these two methods are time-consuming due to the involvement of cross correlation calculation. This paper presents a new CWI calculation approach using Taylor series expansion. The computation time is significantly reduced compared to the cross correlation based methods. This method is demonstrated on a numerical example as well as an experimental example. Comparison of the results between the stretch technique and the method proposed is presented, and the influences of different factors on the CWI analysis are discussed.