Optical trapping with enhanced spatial accuracy and stiffness is possible using super-oscillating light beams that have been structured. Scientists from Tel-Aviv University in Israel and the Central University of Rajasthan in India sent a laser beam to a spatial light modulator (SLM) whose phase could be programmed and then focused the beam using a high-numerical-aperture microscope objective. By applying suitable phase profiles to the SLM, they were able to generate super-oscillating beams with Laguerre-Gauss, Hermite-Gauss and Airy profiles that had features that were smaller than half the wavelength of the light used — the first time that subdiffraction structures have been produced in non-Gaussian beams. By performing optical trapping with these structured, super-oscillating beams, the team was able to manipulate polystyrene nanoparticles with enhanced precision and force than when conventional, diffraction-limited Gaussian beams were used.
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