The lens is one of the most basic tools of optics but the resolution achieved is limited, as if the wavelength of light defined the width of a pencil is used to draw the images. This limit intrudes in all kinds of ways: it defines the storage capacity of DVDs where the laser can only 'see' details of the order of the wavelength; the lithographic processes by which integrated circuits are prepared suffers from a similar limitation. In fact electronics in general has fast run ahead of optics in the race to miniaturization: electrons can be controlled at the level of nanometers, whereas the length scale of optical devices is scarcely sub-micron.

There are two types of light associated with a luminous object: the near field and the far field. True to its name the far field escapes from the object and is easily captured and manipulated by a lens. Unfortunately high resolution details are hidden in the near field and remain localized near the source and cannot be captured by a conventional lens. To control the near field we have developed a new class of materials with properties not found in nature. These new materials derive their properties not from the atomic and molecular constituents of the solid, but from microstructures which can be designed to give a wide range of novel electromagnetic properties.

The lecture will describe the new materials and the principles behind them and show how they may be used to control and manipulate the near field. Finally a prescription will be given for a lens whose resolution is unlimited by wavelength provided that the ideal prescription for the constituent materials is met.

John Pendry is a condensed matter theorist. He has worked at the Blackett Laboratory, Imperial College London, since 1981. He began his career in the Cavendish Laboratory, Cambridge, followed by six years at the Daresbury Laboratory where he headed the theoretical group. He has worked extensively on electronic and structural properties of surfaces developing the theory of low energy diffraction and of electronic surface states. Another interest is transport in disordered systems where he produced a complete theory of the statistics of transport in one-dimensional systems.

In 1992, he turned his attention to photonics materials and developed some of the first computer codes capable of handling these novel materials. This interest led to his present research, the subject of his lecture, which concerns the remarkable electromagnetic properties of materials where the normal response to electromagnetic fields is reversed leading to negative values for the refractive index. This innocent description hides a wealth of fascinating complications. In collaboration with scientists at The Marconi Company, he designed a series of 'metamaterials' whose properties owed more to their micro-structure than to the constituent materials. These made accessible completely novel materials with properties not found in nature. Successively, metamaterials with negative electrical permittivity, then with negative magnetic permeability were designed and constructed. These designs were subsequently the basis for the first materials with a negative refractive index, a property predicted 40 years ago by a Russian scientist, but unrealized because of the absence of suitable materials. He went on to explore the surface excitations of the new negative materials and showed that these were part of the surface plasmon excitations familiar in metals. This project culminated in the proposal for a 'perfect lens' whose resolution is unlimited by wavelength. These concepts have stimulated further theoretical investigations and many experiments which have confirmed the predicted properties. The simplicity of the new concepts together with their radical consequences have caught the imagination of the world's media generating much positive publicity for science in general.