Calibration method for strain measurement using multiple cameras in digital holography

Abstract

Phase-shifting digital holography is a convenient method to measure displacement and strain distributions on the surface of an object. Development of compact and conventional strain distribution measurement equipment for practical use is required for inspection of health monitoring and life lengthening of infrastructures such as steel bridges. Device miniaturization is effective to improve portability, reduce its price and resist vibration. Reducing a number of object beams simplifies the optical setup. Therefore, authors proposed a deformation and strain measurement method to use multiple imaging sensors with an object wave. It is necessary to find corresponding points between the reconstructed images obtained from multiple digital holograms taken by the multiple imaging sensors. In this paper, a calibration method for strain measurement using multiple imaging sensors is proposed. The principle and the experimental results to apply to the strain measurement of a deformed cantilever are shown.