<i>In situ</i> scanning testing system based on Raman spectroscopy

Accurate characterization of localized material regions is a fundamental requirement for advancing materials science and nanotechnology. In situ observation techniques are important for gaining mechanistic insights into material behavior and optimizing structural design. However, the reliability of characterization outcomes can be substantially compromised by unstable scanning systems. This study presents a Raman spectroscopy-based in situ scanning system designed to perform non-invasive characterization during mechanical loading. The integrated platform combines a Raman spectroscopic system with an external precision scanning module and a mechanical loading apparatus. The scanning module employs a low-loss optical path-steering mechanism utilizing mirror assemblies coordinated with precision actuators, enabling focused beam positioning beneath the transparent indenter tip during loading cycles. Stress distribution analysis of single-crystal silicon under Vickers indentation revealed localized stress concentrations near the indenter tip and ridge regions, with tensile components observed along inclined surfaces. These stress patterns are hypothesized to initiate collapse mechanisms and crack propagation, warranting further investigation of stress-microplasticity correlations. Spectral deconvolution enabled the precise determination of peak shifts, while lattice dynamics modeling combined with Hookean analysis established quantitative stress-frequency conversion factors. This methodology establishes a versatile platform for microstructural characterization under complex loading conditions. Future implementations could incorporate thermal, electrical, and magnetic field controls, significantly expanding their applicability in advanced materials research. The technical framework presented herein provides critical insights for establishing structure-property relationships at the micro-nano scale, with substantial implications for both theoretical development and practical engineering applications.