Light fantastic

Fifty years ago yesterday, Theodore Maiman demonstrated the first working laser. At the time, there didn’t seem an obvious use for the technology (although several newspapers ran fanciful stories about ‘death rays’) and it was dubbed ‘a solution looking for a problem‘. Five decades on, lasers are so widespread that we barely notice our everyday encounters with them at the office printer, the supermarket barcode scanner, or the DVD player at home.

DVDs are written and read by laser. (Science Museum)

The basic principle of a laser is pumping energy into a medium to excite its atoms so that they emit photons of light, then amplifying and aligning this emission. The first lasers used ruby rods as the medium – here‘s an explanation of how a ruby laser works.

The chamber of this early laser is opened so that you can see the ruby rod. (Science Museum)

Since then a huge variety of materials has been used in lasers including gold, organic dyes, semiconductors, and gases like helium-neon (the common red laser) and carbon dioxide, widely used for industrial cutting and welding. Or, more weirdly, lasers have even been made from jelly!

The world's first Transversely Excited Atmospheric laser, built at Baldock in 1974, uses a cylinder of carbon dioxide as the medium. (Science Museum)

As well as the now-familiar everyday uses, lasers are increasingly used in medicine. Laser guide stars have helped sharpen the view of major telescopes. Laser weaponry is moving out of the world of James Bond and into reality. One day, lasers might even be used for fusion, providing us with plentiful clean energy. For a more detailed take on the laser’s fascinating history and promising future, check out the special anniversary edition of Physics World. Here’s to the next fifty years.

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