We experimentally demonstrate a wide field surface plasmon (SP) assisted super-resolution imaging technique, plasmonic structured illumination microscopy (PSIM), by combining tunable SP interference (SPI) with structured illumination microscopy (SIM). By replacing the laser interference fringes in conventional SIM with SPI patterns, PSIM exhibits greatly enhanced resolving power thanks to the unique properties of SP waves. This PSIM technique is a wide field, surface super-resolution imaging technique with potential applications in the field of high-speed biomedical imaging.

Super-resolution imaging methods such as structured illumination microscopy and others have offered various compromises between resolution, imaging speed, and biocompatibility. Here we experimentally demonstrate a physical mechanism for super-resolution that offers advantages over existing technologies. Using finely structured, resonant, and controllable near-field excitation from localized surface plasmons in a planar nanoantenna array, we achieve wide-field surface imaging with resolution down to 75 nm while maintaining reasonable speed and compatibility with biological specimens.

A new super resolution imaging method, i.e. Localized Plasmon assisted Structured Illumination Microscopy (LPSIM), is proposed. LPSIM uses an array of localized plasmonic antennas to provide dynamically tunable near-field excitations resulting in finely structured illumination patterns, independent of any propagating surface plasmon dispersion limitations. The illumination pattern feature sizes are limited only by the antenna geometry, and a far-field image resolved far beyond the diffraction limit is obtained. This approach maintains a wide field of view and the capacity for a high frame-rate. The recovered images for various classes of objects are presented, demonstrating a significant resolution improvement over existing methods.

Localized plasmonic structured illumination microscopy (LPSIM) is a recently developed super resolution technique that demonstrates immense potential via arrays of localized plasmonic antennas. Microlens microscopy represents another distinct approach for improving resolution by introducing a spherical lens with a large refractive index to boost the effective numerical aperture of the imaging system. In this paper, we bridge together the LPSIM and optically trapped spherical microlenses, for the first time, to demonstrate a new super resolution technique for surface imaging. By trapping and moving polystyrene and TiO microspheres with optical tweezers on top of a LPSIM substrate, the new imaging system has achieved a higher NA and improved resolution.