Waveguide evanescent waves based structured illumination microscopy with compact structure and flexible design

Abstract

We propose a waveguide-based structured illumination microscopy (SIM) method for super-resolution surface imaging, which can exceed the 2-fold diffraction-limit improvement in traditional linear SIM by employing surface evanescent waves interference patterns. The planar waveguide structure is illuminated by grating coupled focused beams, which avoid a large adiabatic taper area and ensures a small footprint. Moreover, Blind-SIM algorithm is adopted in image reconstruction to avoid sophisticated control for the illumination field. In this designed waveguide structure, the resolution of sparse fluorescent beads improved from 246 nm to 64 nm (3.8-fold improvement) in a 5 × 5 μm2 field of view (FOV). Two beads with an 80 nm gap were resolved with a 45% dip and the resolution of diffraction-limited image of dense object was also enhanced. This method exploits a more compact waveguide structure that is easier and cheaper to fabricate, and the flexibility in design helps to improve the structure with wider FOV and higher imaging resolution.