Grover Swartzlander first began to examine a revolutionary concept in optical physics after studying the flight of a moth. He watched the animal use its wings to create lift, which led to flight. Swartzlander asked a simple question: Could light be used to create the same effect?
This query ultimately led to groundbreaking research that has proven the existence of stable optical lift—the use of a beam of light to move and manipulate particles in the micrometer scale (similar to how the moth uses air to achieve flight).
“Moths, airplanes and automobile spoilers all use the concept of aerodynamic lift to achieve movement,” notes Swartzlander, joint associate professor in RIT’s Department of Physics and the Chester F. Carlson Center for Imaging Science. “Our team has proven that the same basic principle can be used with light to make micro particles ‘fly,’ opening up a host of possibilities for the advancement of microelectronics, biotechnology and astrophysics including the development of better micro machines and improved solar sails for long-distance space travel.”
The results from Swartzlander’s experiments were published in the December issue of Nature Photonic and have led to tremendous publicity for the achievement both in and outside the scientific community. For example, stories on the research have been published in Scientific American and U.S. News &World Report and Swartzlander appeared on the CBC radio program Quirks and Quarks.
“Our computer model predicts and our experiments prove that sustained optical lift is possible and can be used to control particle movement and allow for continued manipulation,” Swartzlander adds.
Swartzlander worked with Timothy Peterson, a master’s student in RIT’s Department of Computer Science, to develop computerized simulations to test the process. He then collaborated with Alan Raisanen, associate director of RIT’s Semiconductor and Microsystems Fabrication Laboratory, and Alexandra Artusio-Glimpse, a doctoral student in the Center for Imaging Science, to create a laboratory experiment using milliwatt-scale laser light and microscopic semi-cylindrical rods.
“When illuminated with the laser light, the rods exhibited both a ‘levitation force’ in the direction of the beam and a ‘lift force’ perpendicular to the beam,” says Artusio-Glimpse, who earned her undergraduate degree in the imaging and photographic technology program. “The rod also rotated into a stable orientation, and subsequently underwent uniform motion.”
Unlike optical tweezers, which is an alternative method to manipulate particles with a focused beam of light, optical lift occurs in uniform illumination, Artusio-Glimpse adds. Numerous rods could be simultaneously lifted and moved in a single uniform beam of light.
Swartzlander says the same force could be used to power micro-motors in biomedical devices or provide a means to steer solar sails designed to send crafts deep into space.
“We are really at the very cutting edge of where this technology could lead in the future,” he continues. “It is our hope that these results will set off a new round of research that could drive even greater discoveries for the specific use of optical lift and optical physics in general.”