British boffins have now built the world's first tractor beam!
The tractor beam has become a staple part of any sci-fi story, in which baddies or goodies are captured - normally when they think they have just escaped. It is also used for less exciting duties like guiding in transmitters, ships with no lifeforms on board and such like.
What we have now is not quite as exciting but is a step in the right direction. Rather than pulling in spaceships, it works on a slightly smaller scale. Well, a molecular scale. It's a tiny beam of twisted laser light that acts like a corkscrew. This can fix on molecules and move them about - rotate them and pull/push them.
What good's that, you cry. Well, it can be used for precise positioning and movement of tiny particles. Hence biologists, chemists and other sorts of micro-scientists can work on a tiny scale without having to touch particles physically or separate them chemically.
But what's more, if it works for small things, there's a good chance that it can be expanded in scale in the future, allowing you to beam your kids off the electricity pylons into a babypen or pull your pint of beer across the table rather than to reach out for it. Think of the possibilities!
The boffins come from St Andrews University in Scotland and reckon the beam can be used for driving motors or small rotating parts of machinery. Something that will become more useful as we make use of micro-technology (have you seen the pic of the tiny propeller submarine inside a human vein?). It may also increase efficiency of machines as there won't be frictional effects of brushes, commutators etc on the motor itself.
The system works by using two laser beams and setting up an interference pattern. The beams refract on hitting an object, causing that object to move into the brightest part of the beam. By adjusting the interference pattern, the object can be pushed/pulled and rotated.
bron:
http://www.theregister.co.uk/content/2/18728.html
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