  Recently, imaging by microspheres and dielectric particle-lenses emerged as a
simple solution to obtaining super-resolution images of nanoscale devices and
structures. Calibrated resolution of ~{\lambda}/6 - {\lambda}/8 has been
demonstrated, making it possible to directly visualize 15-50 nm scale objects
under a white light illumination. The technique has undergone rapid
developments in recent years, and major advances such as the development of
surface scanning functionalities, higher resolution metamaterial superlens,
biological superlens and integrated bio-chips as well as new applications in
interferometry, endoscopy and others, have been reported. This paper aims to
provide an overall review of the technique including its background,
fundamentals and key progresses. The outlook of the technique is finally
discussed.
