Fluorescent digital image correlation applied for macroscale deformation measurement


Fluorescent digital image correlation (DIC) has been implemented on monocular and binocular fluorescence microscopes for shape and deformation measurements at the microscale and even the nanoscale by tracking fluorescent particles. This technique, however, has not been used with regular optical imaging systems for DIC measurements at the macroscale so far. In this Letter, by combining the photoluminescence nature of fluorescent materials and bandpass filtering imaging, we discover that fluorescent DIC also features some distinct advantages in macroscale characterizations, e.g., specular reflection elimination, high speckle contrast, and the capability to simultaneously observe superficial/internal surfaces of transparent structures. To show these advantages and reveal the potential applications of fluorescent DIC, comparative experiments, including shape, displacement, and deformation measurements, were carried out. Furthermore, some issues accompanied by employing fluorescent imaging in DIC were discussed. This study indicates that upgrading classic DIC to fluorescent DIC can significantly improve its performance, enhance its functions, and expand its applications without introducing additional problems.

Applied Physics Letters