Detail of the main component parts of a solid-state ruby laser designed by J K Bradley at Hull University. Standing for 'Light Amplification by Stimulated Emision of Radiation', the laser produces a shaft of intensely coloured (single wavelength) light. The light is also coherent, meaning that all the waves of light are in phase to produce an intense and narrow beam. Laser light in this device is generated using an artificial ruby housed within an elliptical chamber that is shown here with its cover closed.
© Science Museum / Science & Society Picture Library