'Tractor beam' is possible with lasers, say scientists

A laser can act as a "tractor beam", drawing small objects back toward the laser's source, scientists have said.

It is known that light can provide a "push", for example in solar sails that propel spacecraft on a "wind of light".

Now, in a paper on the Arxiv server, researchers from Hong Kong and China have calculated the conditions required to create a laser-based "pull".

'Tractor beam' is possible with lasers, say scientists _51485493_c0028463-spl.h

'Tractor beam' is possible with lasers, say scientists _51485493_c0028463-spl.h

Rather than a science fiction-style weapon, however, the approach would only work over small distances.

The effect is different from that employed in "optical tweezers" approaches, in which tiny objects can be trapped in the focus of a laser beam and moved around; this new force, the authors propose, would be one continuous pull toward the source.

And it relies on directly impinging on an object, making it distinct from an approach demonstrated in 2010 by Australian researchers whose trapping worked by heating air around a trapped particle.

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'Tractor beam' is possible with lasers, say scientists

'Tractor beam' is possible with lasers, say scientists

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