Miniaturized microsphere-assisted microscopy

Microsphere-assisted microscopy is a sub-diffraction-limited imaging technique, which uses dielectric microspheres to collect the near-field information of an object. In this work, the bulk of the classical microsphere-based system is reduced by the simple introduction of a ball lens. The miniaturized imaging system has been designed and vertically assembled. Performance of the proposed dual-sphere system is quantified through numerical simulations and experiments. A theoretical impulse response with a full width at half maximum smaller than half of the wavelength is reached in air. As a proof of concept, 500-nm-period standard gratings and gold nanoparticles are observed without a classical objective, validating a sub-wavelength resolution with a high imaging quality and low aberrations over the field of view.