Old microscopy data reveals optical superresolution in line with information theory

This article reexamines a twenty-year-old experiment showing superresolved intensity variations in the far field using visible light, achieved by nanoscale modifications of the diffraction slit spacing. This study was motivated by earlier unexplained far-field microscopy images that achieved λ/10 resolution without near-field operation. Our hypothesis, backed by 2D finite element analysis, proposes that the local illumination of the scanning tip disturbs the intensity transmitted through the diffraction mask, creating super-resolved images through far-field collection of diffracted energy variations. A review of the historical scientific contributions supports this interpretation. We explore the relationship between information theory, space-bandwidth product concepts, and these observations. These findings demonstrate the possibility of achieving far-field optical super-resolution without requiring near-field proximity of the scanning element, potentially enabling new applications across various wavelengths and imaging scenarios.