Scientists have made a tremendous step towards creating one of the first functional tractor beams. Previous attempts have successfully pushed on particles using photons and were capable of moving particles around in two dimensions, but none have had the ability to pull particles toward the source of the beam. David Ruffner and David Grier from New York University have recently used two Bessel beams projected side by side to move microscopic silica spheres a miniscule distance of about 30 micrometers.
The Bessel beams, types of lasers which create light projected in concentric rings, are used with a lens to make two projected beams overlap one another. As a result, overlapping of the beams allows the scientists to “pull” on particles through tuning of photons. The tuning of the photons causes the photons in the bright areas to move towards the dark areas closer to the source, moving in a reverse motion. Additionally, if a particle is present in the area, then the particle gets pushed backwards from the motion of the photons.
Ruffner has stated that the beams could possibly be used to collect samples from asteroids, comets, or even atmospheres. The major advantage of this technology is that it would be able to operate in the vacuum of space, where as many previous attempts for a tractor beam were dependent upon temperature variations, stripping them of their ability to operate in space. Furthermore, due to its use of photons to “pull” particles it has a very wide range of use compared to past tractor beam technologies. Ruffner says it is still in its infancy. As expected, NASA is already immensely interested in putting it to use.