Play tiny Tetris using a laser beam

Read more: Tricks of the light

Game on, microbeads. This micron-sized game of Tetris, developed by students from VU University Amsterdam, is being played using a light-trapping device called optical tweezers rigged up to a computer game. The microscopic glass spheres are in the clutches of a highly- focused laser beam that keeps the beads in position while moving new Tetris pieces.
"Optical tweezers enable manipulation on the sub-micrometre scale as if you're handling real tweezers," says physicist Joost van Mameren, one of the creators of the video. "The focus of this beam acts as an attraction point for small particles: they get sucked into the focus and cannot escape."
At the end of the clip, the laser is turned off and the Tetris beads quickly drift out of position.
When optical tweezers are not puzzling over Tetris, researchers use the tool to manipulate bacteria, pry open DNA's double helix, and test the mechanics of nature's smallest structures.
For more fun with photons, read our full-length feature covering nine fabulous light spin-offs.
If you enjoyed this video, see how you can manipulate molecules with your iPad or play a game of Pong with a laser gadget.

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