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.
A new method is presented for synthesizing arbitrary grey level intensity patterns based on phase contrast imaging. The concept is grounded on an extension of the Zemike phase contrast method into the domain of full range [O;2ic] phase modulation. By controlling the average value of the input phase function and by choosing appropriate phase retardation at the phase contrast filter, a pure phase to intensity imaging is accomplished.The method presented is also directly applicable in dark field image synthesis [1].Preliminary experimental results are demonstrated for binary-only phase modulation.
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