Metal slab superlens-negative refractive index versus inclined illumination: Discussion

I describe experiments using a combination of an optical microscope and a plasmonic ultrathin condenser (UTC). The UTC's structure is similar to the original proposal of a silver slab superlens. I show that the observed improvement in image resolution is determined by the well-known equation describing the resolution obtainable when a condenser is included in the microscope setup. I argue that the described experiments indicate that the so-called metal slab superlens is better described as a novel ultrathin microscope condenser, and the observed improvement in resolution is due to the illumination of the object under observation with inclined light produced by the plasmonic UTC. Implications of this opinion for the development of an optical nanoscope based on plasmonic UTCs are presented.