Isotropic super-resolution interferometric plasmonic microscopy.

Surface plasmon resonance microscopy (SPRM) is a highly sensitive, label-free optical imaging technique. However, its spatial resolution is limited by the directional propagation of surface plasmon waves (SPWs), resulting in anisotropic imaging. To address this limitation, we propose an isotropic super-resolution interferometric plasmonic microscopy (ISR-IPM) technique. This method combines multi-angle SPWs excitation, system transfer function theory, and frequency-domain reconstruction algorithms to expand spatial frequencies in all directions. The experimental results show that ISR-IPM effectively eliminates the anisotropy of traditional SPRM, fundamentally overcomes the optical diffraction limit, and achieves a spatial resolution of ~150 nm for nanoscale targets. This technology may further provide a powerful platform for nanoscale imaging, quantitative analysis of biomolecular dynamics, and comprehensive characterization of surface plasmon fields.