Miniaturized handheld Raman imager based on 2D MEMS scanning for non-destructive analysis of thermally sensitive samples.

High-power-density laser focusing can enhance Raman throughput but often causes thermal degradation in dark or heat-sensitive samples, leading to fluorescence background, peak distortion, or even material combustion. Here, we present a handheld Raman imaging system incorporating a two-dimensional micro-electro-mechanical (2D MEMS) mirror that enables programmable spatial scanning of the excitation beam. By distributing laser energy temporally and spatially, the proposed system effectively suppresses photothermal damage while preserving spectral fidelity. Replacing conventional 2D nano-positioning stages with a MEMS scanning module enables, to the best of our knowledge, the first handheld Raman device capable of performing full-field (i.e., simultaneous imaging of the entire field of view) chemical imaging. Experiments on four dark or thermally sensitive substances, including potassium permanganate and Sudan III, demonstrate significant reductions in localized power density, improved signal-to-noise ratio (SNR), and complete elimination of sample damage. Point array scan imaging of a composite pharmaceutical tablet further visualizes the spatial distribution of its chemical components, confirming the system's practical utility for non-destructive, field-deployable Raman imaging. The integration of MEMS scanning technology addresses long-standing limitations of conventional Raman systems and aligns with the growing demand for miniaturized, portable optical sensors.