Multiple dual-beam traps for three-dimensional position control of particles

摘要

We demonstrate an optical micromanipulation system that enables simultaneous trapping of a plurality of particles and interactive control of their trapping positions in three dimensions (3D). This functionality is achieved through the application of phase-only spatial light modulators (SLM) in a highly efficient generation of advanced counterpropagating-beam or dual-beam traps in an extended array. The array of counterpropagating-beam traps is composed of the s and p -polarized components of a dynamically reconfigurable intensity pattern created via the generalized phase contrast method. A power-preserving scheme using a spatial polarization modulator (SPM) allows us to vary the relative strengths of the two orthogonal polarizations thereby controlling the axial trap positions of the particles. Experimental results show the interactive manipulation of polystyrene microspheres in 3D achieving a dynamic range in axial position control as large as 20μm.