There is widespread and strong interest in trying to fabricate a metamaterial in which both the permittivity and permeability are equal to-1 in order to achieve sub-wavelength imaging.Several metamaterial constructs have been proposed with varying degrees of success because of inherent losses,limited bandwidth and scattering from the abstracted circuit elements constituting the artificial material itself.A further limitation is the need to capture evanescent components from the object to be imaged that requires the lens to be located near the object.We have studied the underlying models and constraints that influence the design of a negative index lens and present this analysis as well as reviewing the opportunities.There are inevitable and well-known trade-offs between lens thickness,wavelength,dispersion and absorption.However,these can be characterized both numerically and experimentally,suggesting that a computational imaging approach to the recovery of sub-wavelength features might be effective.Depending on the specific details of the metamaterial employed for imaging,one can consider the data acquired to represent a set of coded apertures.