| Abstract: | There is an increasing demand for new technologies to rapidly measure individual nanoparticles in situ for applications,including early-stage diagnosis of human diseases and environmental monitoring. Here, we demonstrate a label-free wide-field optical microscopy capable of sizing dispersed non-luminescent dielectric nanoparticles(with diameters down to 22 nm) with 10 nm accuracy. This technique utilizes enhanced nanoparticle-perturbed scattering by surface plasmons created on a gold film.In the meantime, an azimuthal rotation illumination module is installed on this microscope and a differential image processing technique is carried out. The relationship between the scattering intensity and the particle size was experimentally measured with good consistency with the theoretical prediction. The capability of precise measurement of the size of dispersed nanoparticles within a larger field of view in a label-free, non-invasive and quantitative manner may find broad applications involving single nanoparticle chemistry and physics. |
