Shack-Hartmann multiple-beam optical tweezers.

We introduce a new method for generating an array of programmable optical tweezers based on the principle of the Shack-Hartmann wave front sensor. In this approach, a lenslet array divides a laser beam into multiple point sources that are subsequently imaged onto the sample plane of an inverted microscope. This results in a matrix of tightly focused beams used for local confinement and manipulation of micron-sized dielectric particles in an aqueous solution. Using a spatial light-modulating device, the phase profile of the laser beam is computer-encoded providing for controlled spatial deflections of the trapping beams.