Quantification of resolution in microspherical nanoscopy with biological objects

Abstract

Microspherical Nanoscopy uses a microsphere as a contact lens which allows for resolving nanometer sized objects using visible light. Nanoplasmonic structures have been used in combination with microspherical nanoscopy to achieve resolutions beyond the classical diffraction limit. The mechanisms of such super-resolution imaging can include the optical near field coupling and the virtual image magnification effects. In this work, we quantify the resolution of microspherical nanoscopy using a basic fluorescence microscope equipped with a standard 40× (NA = 0.6) objective which can be found in most of the labs performing histology or microscopy analyses in a clinical environment. We perform the resolution quantification in three distinct structures: (1) F-Actin proteins on a microscope slide, (2) F-Actin proteins imaged through a high index microsphere on a microscope slide, and (3) F-Actin proteins imaged through a high index microsphere on a nanoplasmonic array. The high index microspheres (n∼2) are embedded in an elastomer slab. Using a microscope we achieve a resolution of (1) ∼λ/0.7, (2) − λ/2.5, and (3) ∼λ/2.8 for each situation.