Tractor Beam Pulls Tiny Particles Backward

Professor Pavel Zemanek and his colleagues at the Institute of Scientific Instruments (ISI) of the ASCR built a laser that moves tiny spheres of polystyrene floating in water. While in science fiction programs such as “Star Trek,” tractor beams are used to move massive objects, the unique research published in Nature Photonics (2013, 7, 123–127) is limited to moving microscopic particles. Changing the way the light is polarized changes the direction the spheres move. The ISI scientists also found that at certain sizes, the spheres arrange themselves into neat rows as they move, bound by the light itself.
The practical applications could be diverse. The tractor beam is very selective in the properties of the particles it acts upon, so one could pick up specific particles in a mixture. For example, this laser could be used to separate white blood cells.