Let there be light! Or, rather, let there be Light Amplification by Stimulated Emission of Radiation. Quite a mouthful - which is why we use its acronym, LASER.

As the name suggests, lasers are devices which energise atomic particles, electrons, and then 'stimulate' them to 'emit' their energy as light particles, photons. This sets off a chain reaction where more and more electrons are stimulated to emit photons, 'amplifying' the light, which is focused with mirrors. When all the photons propagate in step with each other, they form a coherent, potentially very intense and highly directional beam.

Lasers first appeared only recently, in the 1960s. Yet, their impact has been enormous, having become indispensable tools in industry, scientific research, communication, medicine and the arts.

The next time you turn on your CD player, remember that, without lasers, it wouldn't exist.

Laser theory was first described by Albert Einstein in 1917. When it came to credit for turning theory into practice, there was a bit of a tussle - a not unusual occurrence in the halls of academe. The first laser patent application was lodged in 1958 by American physicists Arthur Schawlow and Charles Townes. This was granted - then promptly challenged by another American scientist, Gordon Gould, who was finally granted a patent in 1977.

Lasers are a great example of life imitating art. That year, 1977, also saw the release of the first Star Wars film, which featured fictional laser weapons. Six years later, the United States began work on an anti-missile system involving lasers, dubbed, inevitably, 'Star Wars'. After the fall of the Soviet Union in 1991, it was shelved. However, the project was recently revived, and trials are under way using laser beams as weapons in space.

- Sue McAlister