A Compact and Calibration-Free High-Temperature High-Speed Stereo-DIC System for Deformation Measurement Through Confined Viewports

High-speed stereo-digital image correlation (stereo-DIC) using two synchronized high-speed cameras has become a powerful method for quantitatively assessing surface displacement and strain fields of various samples undergoing dynamic loading or high-speed motion. However, in sealed high-temperature environments with confined viewports, stereo-imaging with two synchronized cameras is constrained and calibration within such environments is challenging or even impossible. This study introduces a compact and calibration-free high-temperature high-speed stereo-DIC system that utilizes a single high-speed camera and a bi-prism to achieve full-field 3-D dynamic deformation measurements through confined viewport. The camera is equipped with a bilateral telecentric lens (BTLs) that maintains constant image magnification, simplifying the imaging process to an orthographic projection without requiring calibration. Additionally, the bi-prism creates two distinct optical paths, allowing two views of the specimen to be captured on the camera sensor simultaneously, resulting in a compact setup. Experimental validation including comparisons with strain gauges, thermal deformation and tensile strain tests under electromagnetic induction heating, and vibration measurements in high-temperature environment demonstrates the system’s capability to accurately measure 3-D dynamic deformations at elevated temperatures. These results suggest the potential for monitoring dynamic deformation in sealed high-temperature environments, especially for aerospace and advanced manufacturing, where real-time deformation tracking under extreme conditions is essential for performance evaluation.