SPP tomography: a simple wide-field nanoscope.

We explore the wide-field optical nanoimaging capabilities of the surface plasmon polariton (SPP) tomography technique. We show that nanofeatures with lateral dimensions smaller than λ/20 can be observed in the surface emission (SE) images of plasmonic crystals with a period of 300 nm. Moreover, as a proof-of-concept, we demonstrate that SPP tomography permits to resolve two single objects with a center-to-center separation of 200 nm and edge-to-edge separation as small as λ/7. We present a comprehensive discussion about the nanoimaging capabilities of the SPP tomography technique. In contrast to other optical subwavelength resolution techniques, in our approach for imaging nanosize features, enhanced evanescent waves are coupled to the far-field via leakage radiation associated with SPPs excited by near-field fluorescence; therefore wide-field images, which are not out-of-plane diffraction-limited, are formed directly in the microscope's camera. We also discuss additional imaging processing capabilities associated with the fact that SPP tomography SE images are formed by the microscope lenses through an analog tomography process. © Wiley Periodicals, Inc.