Investigation of super-resolution in microsphere-assisted microscopy with the Poynting vector of the dipole model

In this paper, the Fourier spectrum of image in microsphere-assisted microscopy(MAM) and wave number decomposition of Poynting vector of dipole model are compared for the first time to study the super-resolution performance within several wavelengths in MAM. Firstly, an experiment using microsphere-assisted microscopy is performed, and the Fast Fourier Transformation(FFT) spectra of the images along the distance are studied. Then Poynting vector in the point dipole field is theoretically investigated based on the spectral decomposition of Dyadic Green's Function. Our study finds that the result of decomposition of Poynting vector corresponds with propagation results of components with different transverse wave numbers in experiment. This discovery can be used to explain the physical origin of super-resolution performance at the distance larger than one wavelength. Our work is the first effort (to our knowledge) to associate the Fourier spectrum and decomposition of Poynting vector together and it may contribute the quantitative exploration of super-resolution performance in MAM in the future.