C2LI: Enhancing Structural Color Sensing and Imaging via Complementary Color Laser Illumination

Abstract Structural color, a phenomenon arising from nanoscale interactions of light with materials, has the potential to unveil biological, chemical, physical, and mechanical characteristics directly to human users with high spatiotemporal resolution. However, its impact is often constrained by challenges in perceptual differentiation of subtle color variations. Laser imaging is one promising approach for addressing these challenges, yet is typically optimized for amplifying physical signals rather than for the psychophysical nature of color perception. Here, we introduce complementary color laser illumination (C 2 LI) as an imaging technique that accesses enhanced psychophysical non‐linearities in chromatic color perception—effectively boosting perceived color differences by maximizing chromatic contrast sensitivity, without reliance on digital processing. We demonstrate C 2 LI enables perceptually enhanced sensing and imaging in tasks such as microfluidic refractometric sensing, phase contrast enhanced microscopy, and semiconductor inspection–allowing users to detect subtle changes in sample properties that could otherwise remain imperceptible. C 2 LI’s ability to harness the interplay of structured light, structural color, and the psychophysics of color perception offers a new pathway for enhancing the fidelity of sample analysis, optimized for color vision. This makes C 2 LI well‐suited for sensing and imaging applications ranging from environmental and biomedical diagnostics to semiconductor metrology and defect inspection.