Super-resolution imaging by high-index microspheres immersed in a liquid

We demonstrate that the super-resolution imaging of a commercial Blu-ray® disk containing a one-dimensional array of 200 nm width stripes separated by 100 nm width grooves can be achieved using high-index microspheres in a liquid environment. By using barium titanate glass microspheres (2-20 μm diameters) with index around 1.9 totally immersed in isopropanol with index 1.37 we demonstrate better than λ/6 far field resolution, where λ= 600 nm is the peak wavelength of the white-light illumination system. The results of this work can be used in biomedical microscopy, microfluidics and nanophotonics applications for imaging individual cells and/or nanoparticles in a liquid environment.