Design and validation of a demand-oriented single-camera stereo-DIC system with a four-mirror adapter

Four-mirror-assisted single-camera stereo-digital image correlation (stereo-DIC) system overperforms conventional two-camera stereo-DIC system in terms of system compactness, cost investment and easy implementation. However, how to design a suitable four-mirror adaptor orienting a specific demand has not been clearly described in previous researches. To address this issue and satisfy practical requirements encountered in real applications, we proposed a design strategy for determining the optimal structure of a four-mirror adaptor. Specifically, to optimize the structural parameters of a four-mirror adaptor, the proposed design strategy comprehensively considers various factors, including the desired field of view (FOV), working distance, measurement accuracy, system compactness as well as the parameters of available devices (camera and lens). After implementing the algorithm based on the degrees of freedom (DOF) of the imaging system, an optimal solution can be determined from all the solutions that can satisfy the identical requirements. The designed four-mirror adapter is then printed by a 3D printer, and can be directly attached to the lens for single-camera pseudo-stereo imaging. Further, two specific design paradigms demonstrated the correctness and effectiveness of the proposed design strategy. It is expected that the proposed method can help the researchers to construct a demand-satisfied yet compact four-mirror-assisted single-camera stereo-DIC system.