Noncontact Young's Modulus Measurement Using a Laser Interferometry–Digital Microscopy System: From Manganese Steel to Polylactic Acid Composites

Abstract

High-precision measurement of Young's modulus is essential for evaluating the mechanical properties of materials, yet traditional methods often exhibit high error rates and system complexity. This study presents a noncontact, fully digital sensor system that integrates Lloyd's mirror interferometry with digital microscopy imaging. The system employs a uniaxial stretching device and a Lloyd's mirror optical path to capture real-time interference fringe images, and utilizes a multi-algorithm fusion framework for accurate fringe centerline positioning. A MATLAB-based GUI enables one-click automated data processing. Experimental results show that the system measures the Young's modulus of manganese steel wire as 2.004 × 100 GPa with a relative uncertainty of 1.36%, outperforming CCD-based methods (relative error > 4%). The Young's modulus measurements for pure aluminum wire, polylactic acid (PLA) composites, and aluminum alloy sheets are 0.776 × 100 GPa (relative uncertainty 2.63%), 3.016 × 100 GPa (relative uncertainty 1.19%), and 0.729 × 100 GPa (relative uncertainty 4.21%), respectively. Overall, the proposed system is a promising solution with broad engineering applicability for high-precision elastic property measurements under complex conditions owing to its applicability to both metallic and non-metallic materials.