Stable optical lift proved

The existence of stable optical lift, or the use of a beam of light to move and manipulate particles in the micrometer scale, has finally been proved. Applications include astrophysics, biotechnology and microelectronics. Someday it could be used to enable long-distance space travel or to power micromachines.

“Airplanes and automobile spoilers use the concept of aerodynamic lift to achieve movement,” said Grover A. Swartzlander, joint associate professor in the department of physics and the Chester F. Carlson Center for Imaging Science at Rochester Institute of Technology. “Our computer model predicts and our experiments prove that sustained optical lift is possible and can be used to make particles move perpendicular to the direction of the light flow. Combined with the previously known ‘levitation force’ of light, the specially shaped particles can be made to ‘fly.’ ”

Grover A. Swartzlander, left, led a Rochester Institute of Technology (RIT) research team that has proved the existence of stable optical lift. Also pictured are Timothy Peterson, second left, a computer science master’s student; Alan Raisanen, associate director of the Semiconductor and Microsystems Fabrication Laboratory; and Alexandra Artusio-Glimpse, right, a doctoral student in imaging science. Courtesy of William Dube, RIT.

Optical tweezers manipulate particles using a focused light beam, but optical lift occurs in uniform illumination, which means that particles could be lifted and moved simultaneously in a single uniform beam of light.

To test the process, Swartzlander and his colleagues developed computer simulations, then devised an experiment using milliwatt-scale laser light and microscopic semicylindrical rods. The rods, when illuminated by the laser, exhibited a levitation force in the direction of the beam and a lift force that was perpendicular to the beam. They also rotated into a stable orientation and subsequently underwent uniform motion.

The work was published online in December 2010 by Nature Photonics.