And to the ever-growing list of real-life scientific inventions and breakthroughs that echo the fictional Star Trek universe let’s add... a tractor beam. According to a CNET.com headline that very succinctly puts the news into a comprehensible nutshell, “Physicists have built a tractor beam out of lasers that can both repel and attract objects across distances 100 times farther than previously possible.”
The ensuing article then details how the hollow laser beam -- bright around the edges, but hollow in the middle -- moved particles 0.2 mm in diameter distances up to 20 cm (7.87 in), that being the 100 times farther than in any earlier experiments. "Demonstration of a large scale laser beam like this is a kind of holy grail for laser physicists," CNET writer Michelle Starr quoted Professor Wieslaw Krolikowski as saying. Krolikowski is with the Research School of Physics and Engineering at The Australian National University (ANU).
The ANU team of scientists/researchers relied on heat rather than photon momentum to propel particles on a microscopic level, trapping microscopic gold-coated hollow glass particles in the laser beam’s dark center. “Energy from the laser travels across the surface of the particle, where it is absorbed,” Starr wrote, detailing the process. “This creates hotspots; when air particles collide with these hotspots, they heat up and shoot away from the particle; in turn, the particle then recoils in the opposite direction. In order to then steer the particle, the team carefully controls the polarization of the laser beam to heat up the desired portion of the particle's surface.
Starr concluded by stating that practical applications of the breakthrough “could include controlling atmospheric pollution, or retrieving tiny, delicate or dangerous particles for sampling. It could also be scaled up for larger uses.
Visit http://www.cnet.com/news/physicists-create-reversible-laser-tractor-beam/ to read the full article.