A More Powerful Tractor Beam
Tractor beams have become a staple of science-fiction, but their real-world counterparts are a far cry from Star Trek, as you might suspect. Still, physicists have developed a laser that can attract or repel objects.
Dr. Vladlen Shvedov and Dr. Cyril Hnatovsky have demonstrated their tractor laser beam, which is bright around the outside and dark in the middle. The beam can move an object that is 0.2mm a distance of 200mm – 100 times further than previous experiments.
Dr. Hnatovsky explains:
“We have devised a technique that can create unusual states of polarisation in the doughnut shaped laser beam, such as star-shaped (axial) or ring polarised (azimuthal).
“We can move smoothly from one polarisation to another and thereby stop the particle or reverse its direction at will.”
The beam works by heating a portion of the particle, creating a hot spot on the surface. Air molecules hitting the hot spots are accelerated away, producing a tiny amount of thrust. The key is that the direction of thrust can be controlled by altering the beam. (This also means that this technique will not work in a vacuum.)
The researchers hope that this technique will work at distances up to several meters. This could be useful for applications where tiny delicate particles need to be manipulated. This could include removing unwanted pollutants from the air.
This type of tractor beam, however, will not scale up for use moving large objects in space, such as enemy spacecraft attempting to escape.