A team of researchers from RIT has proven the existence of stable optical lift-the use of a beam of light to move and manipulate particles at the micrometer scale. This method, similar to air movement over airplane wings generating lift, is used to achieve particle movement using light.
The technique has significant applications in many fields, including biotechnology, astrophysics, and microelectronics, and could eventually be used to power micro-machines or enable solar sails for long-distance space travel.
"Airplanes and automobile spoilers use the concept of aerodynamic lift to achieve movement," notes Grover Swartzlander, joint associate professor in RIT's department of physics and the Chester F. Carlson Center for Imaging Science. "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.'"
Swartzlander's team first developed computerized simulations to test the process and then created a laboratory experiment using milliwatt-scale laser light and microscopic semi-cylindrical rods. As expected, 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.
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. Numerous rods could be simultaneously lifted and moved in a single uniform beam of light.
The research team included Alan Raisanen, associate director of RIT's Semiconductor and Microsystems Fabrication Laboratory, Timothy Peterson, a master's degree student in RIT's department of computer science, and Alexandra Artusio-Glimpse, a graduate of the RIT photographic technology program and a current doctoral student in the Center for Imaging Science.