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Optical Tweezers Inch Us Ever Closer to Tractor Beams

By Norman Chan

Levitating nanodiamonds with a focused laser.

Researchers at the University of Rochester demonstrate the ability of focused lasers to levitate very small objects in a vacuum. In this experiment, assistant professor of optics Nick Vamivakas focused a laser to a very small region of space in a vacuum, and then sprayed that space with an aerosol containing dissolved nanodiamonds--each as small as 100 nanometers (about one-thousandths the diameter of hair). The process, called laser trapping, is described in a paper published this week in the journal Optics Letters. It works because of the ability of light to exert push and pull forces on objects, a trait that we don't normally attribute to light because it doesn't affect us at human scale. Scientists have been able to use light to manipulate microscopic objects in the past using this optical tweezer technique, but this is the first time that nanodiamonds have been trapped by light.

Photo credit: J. Adam Fenster/University of Rochester

The video below explains the process in greater detail: