Simultaneously measurement of strain field and Poisson's ratio by using an off-axis phase-sensitive optical coherence elastography

Phase-sensitive optical coherence elastography (PhS-OCE) is a novel functional imaging modality capable of mapping strain fields inside semi-transparent materials. In this work, an off-axis PhS-OCE was further developed to measure strain field and Poisson's ratio simultaneously. Based on the intrinsic equations of continuum mechanics, the relationship between the elastic parameters of the measured material and the physical quantity (i.e. optical path difference) of PhS-OCE was first established. For validation, the depth-resolved strain field and Poisson's ratio of a silicone rubber film were quantitatively measured during tensile tests. The experimental results, such as the estimates for Poisson's ratio, agreed with the reference values. Moreover, phase difference maps of bilayer composites were discussed, indicating the effectiveness and potential of the proposed off-axis measurement method.