Development of efficient and durable sources of white light

This review presents a brief history of the development of light sources over the centuries to provide one of the human race's basic needs - light. Recent moves in Europe to encourage the adoption of compact fluorescent lamps as more energy-efficient replacements for incandescent lights, despite certain drawbacks, are described. Rapid strides are now being made in the development of solid-state 'white' lights which are already sufficiently durable and efficient to warrant adoption for both domestic and public lighting purposes. Their basic construction and comparative performance, properties and uses are fully described, together with the many ideas for improving their brightness and durability still further. Solid-state devices offer additional savings compared with those which should be achieved under the EU's targeted replacement of incandescent lights by 2012, and later one can expect such devices to compete with high-pressure sodium luminaires for street lighting.