Design and Validation of a Compact Bi-Prism- Based Single-Bilateral-Telecentric-Camera Stereo-DIC System

Bi-prism-based single-bilateral-telecentric-camera stereo-digital image correlation (SBTC stereo-DIC) is a recently developed variant of single-camera stereo-DIC technique, featuring attractive advantages of easy implementation, calibration-free imaging model, and high accuracy. However, the effects of key structural parameters (e.g., the prism angle and the location of the bi-prism) on the metrological performance of the system, e.g., field of view (FOV), system compactness, working distance and measurement precision, and how to design a compact bi-prism-based SBTC stereo-DIC system, remain unclear. To address these problems, we first investigated the influence of the key geometric parameter, the horizontal distance between the bi-prism and the bilateral telecentric lens (BTL), on the metrological performance of bi-prism-based SBTC stereo-DIC in terms of system compactness, FOV, and measurement precision. Based on these findings, a bi-prism adapter was designed and printed by a 3-D printer that can be directly attached to the BTL as a spectroscope for single-camera pseudo-stereo imaging. The metrological performance of the established bi-prism-based single-BTL stereo-DIC systems was experimentally examined by the FOV validation test, cylinder translation, and low-carbon steel tensile tests. The results of this work provide practical guidance on constructing a compact bi-prism-based single-BTL stereo-DIC system.