Exact transformation optics by using electrostatics

We present a novel method for designing transformation optical devices based on electrostatics. An arbi-trary transformation of electrostatic field can lead to a new refractive index distribution, where wave-fronts and energy flux lines correspond to equipotential surfaces and electrostatic flux lines, respectively. Owing to scalar wave propagating exactly following an eikonal equation, wave optics and geometric optics share the same solutions in the devices. The method is utilized to design multipole lenses derived from multipoles in electrostatics. The source and drain in optics are considered as corre-sponding to positive charge and negative charge in the static field. By defining winding numbers in vir-tual and physical spaces, we explain the reason for some multipole lenses with illusion effects. Besides, we introduce an equipotential absorber to replace the drain to correspond to a negative charge with a grounded conductor. Therefore, it is a very general platform to design intriguing devices based on the combination of electrostatics and transformation optics. (c) 2021 Science China Press. Published by Elsevier B.V. and Science China Press. All rights reserved.