Experimental determination of trapping efficiency of optical tweezers |
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Authors: | H. Cabrera J.J. Suárez-Vargas A. López H. Núñez G. Carvalho G. Coceano |
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Affiliation: | 1. Laboratorio de óptica Aplicada, Instituto Venezolano de Investigaciones Científicas IVIC, Mérida, Venezuela.;2. The Abdus Salam International Centre for Theoretical Physics ICTP, Trieste, Italy.hcabrera@ictp.it;4. The Abdus Salam International Centre for Theoretical Physics ICTP, Trieste, Italy.;5. Laboratorio de dinámica no lineal y sistemas complejos, Instituto Venezolano de Investigaciones Científicas IVIC, Caracas, Venezuela.;6. Laboratorio de dinámica no lineal y sistemas complejos, Instituto Venezolano de Investigaciones Científicas IVIC, Caracas, Venezuela.;7. Fundación Centro Nacional de Desarrollo e Investigación en Telecomunicaciones CENDIT, Caracas, Venezuela.;8. Fundación Centro Nacional de Desarrollo e Investigación en Telecomunicaciones CENDIT, Caracas, Venezuela.;9. Optical Manipulation Lab, Istituto Officina dei Materiali CNR-IOM, Trieste, Italy. |
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Abstract: | We report an experimental determination of trapping efficiency of optical fields acting on spherical particles diluted in viscous fluids. This parameter was derived from experimentally calculated trap stiffness for micron-sized silica beads with particle radii of 1.5 and 4.8 microns, respectively. In order to obtain the trap stiffness, we used the equipartition theorem, and introduced an experimental procedure to calibrate the optical tweezers set-up. The method consists of the calculation of the trapping efficiency by using the curves of the trap stiffness vs. the incident power. Using this approach we measured the efficiency for different values of displacements of the beads in the optical trap, and compared these results with numerical and theoretical calculations reported in the literature, and an excellent agreement was found. We have shown that the ratio of efficiencies is very close to the ratio of the particle radii. |
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Keywords: | lasers biophysics biological applications cellular structures medical applications microscopy |
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