Optical nanoscopy with contact Mie-particles: Resolution analysis

摘要

The theoretical limits of resolution available in microspherical nanoscopy are explored using incoherent point emitters in the air. The images are calculated using a two-dimensional model and solving the Maxwell equations which account for the wave effects on the sub-wavelength scale of the emitter-microsphere interaction. Based on our results, we propose to use small dielectric particles with diameters λ≤D≤2λ made of a high-refractive-index material n ~ 2 for imaging sub-wavelength objects. It is shown that such particles form virtual images below and real images above them. At wavelengths of the Mie resonances, these images have slightly better than ~λ/4 resolution that can be attributed to the image magnification in close proximity to the object and contributions of its near field. The resonant super-resolution imaging of various point-like objects, such as dye molecules, fluorophores, or nanoplasmonic particles, can be realized by using narrow bandpass optical filters spectrally aligned with the Mie resonances.