from the in-a-spin dept.
Both vik and Brian Wang noted the news that Researchers at St. Andrews University in Scotland have developed a technique using specialized lasers to spin microscopic objects, such as chromosomes, without making physical contact. They report that they have used infrared lasers to spin tiny glass spheres, a glass rod and even the chromosome from a hamster. The light pulls the objects around at speeds up to five revolutions a second, but is gentle enough not to damage delicate molecules. The work is a variation of the "optical tweezers" technique: as a beam of light bends around an object, the light exerts a force on it. At the microscopic level, the force of laser light bending around tiny objects is strong enough to trap them. By moving the beam, the trapped objects move as well, allowing optical tweezers to push and pull microscopic objects. In the new research, the researchers combine the light of two lasers to create a spiral interference pattern, a pinwheel-like pattern of bright and dark spots. Changing the optical path length causes this pattern, and thus the trapped objects, to rotate.
Brian Wang also noted "My observation is that this combined with Arryx (http://www.arryx.com/overview.html) Holographic Optical Trap ("HOT") technology for splitting one laser into thousands of manipulated lasers might scale into a massive photonic assembly system at the microscopic level."
The research report appeared in the 4 May 2001 issue of Science. Additional coverage can be found on the New York Times website.