Paul Urbach and Zheng Xi published paper on resolution with far field optics in Photonics Magazine

It is common knowledge in optics that, when only tar fields are measured, there is a fundamental limit to the resolution given by the wavelength of the light. Yet research continues to beat this fundamental limit.

Even a Nobel Prize was awarded for super-resolution some years ago. In this article we consider the apparent contradiction and explain under what circumstances the classical limit of resolution can be beaten. As will be seen, these circumstances are quite special, but if they can be realised super-resolution is possible.

The whole article can be read here.