Observation of microparticle motion under optical tweezers

Abstract

We report measurements of dielectric monodisperse polystyrene microspheres trapped by a collimated laser beam. The experiment relies on the gradient forces and torques generated by electromagnetic fields. By analyzing the amplitudes of periodic oscillations, we determine the trapping spring constants corresponding to various incident laser intensities and establish the relationship between the restoring force and the optical field. The results provide an effective improvement for characterizing the mechanical properties of particles in micrometer dimensions, with hints for precise instrumental control.

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