Optical microscopy with super-resolution by liquid-immersed high-index microspheres

Abstract

We study super-resolution capability of liquid-immersed high refractive index (n~1.9–2.1) barium titanate glass microspheres with diameters from several microns up to hundreds of microns. Imaging is provided in a conventional upright microscope with the spheres placed in a contact position with various semiconductor and metallic nanostructures. Using a commercial Blu-ray disk, we demonstrate an ability to discern 100 nm feature sizes which cannot be resolved by conventional microscopy. Using silver nanowires with diameter about 100 nm, we demonstrate ~1.7 times improvement in spatial resolution compared to conventional diffraction-limited far field microscopy. Using two-dimensional nanoplasmonic arrays, we demonstrate high resolution imaging by using objectives with surprisingly small numerical apertures. The last property is attractive for high-resolution imaging at long working distances. This imaging technique can be used in biomedical microscopy, microfluidics, and nanophotonics applications.