Nanospeckle illumination microscopy via randomly localized near-field speckle by nanocomposite islands

Abstract

Beyond structured illumination microscopy (SIM) which uses diffraction-limited light illumination, specially designed nanostructures such as metallic nanoantenna arrays generating localized surface plasmon have been developed to expand the frequency information without increasing photon energy. In this study, disordered temperature-annealed nanocomposite islands were used to create random distribution of nanospeckles because nanoisland substrates can be mass-produced in a large observation area by thin film deposition and annealing process. In our nanospeckle illumination microscopy (NanoSIM) system, azimuthal scanning illumination (ASI) on nanoislands creates a randomly localized nearfield distribution that induces an arbitrary number of fluorescence images. By the difficulty of obtaining structured illumination patterns of random nanostructures, images were reconstructed using a modified blind-SIM algorithm which fits well with the ASI system. A 100 nm fluorescent nanobead experiment confirms that NanoSIM provides resolution enhancement of spatial information in good agreement with the results obtained from AFM images. We emphasize that using random nanospeckles of disordered nanocomposite islands can provide highly accessible super-resolution. The results can be applied to imaging and sensing techniques, such as switching-based multi-channel microscopy.