Focused-Laguerre-Gaussian 3D-Trapping and Spanner at Low Numerical Aperture

Abstract

Abstract. Stable 3D micromanipulation by light requires that gradient force overcome axial scattering force introduced by an objective lens. Although high numerical aperture (NA) objective lenses in conventional optical tweezers could match the requirement, the dramatic limited axial working range and a narrow view field draw back the application seriously. With purpose to improve the application of micromanipulation, we succeed in the three dimensional (3D) trapping of polystyrene microspheres with a low-numerical-aperture (NA=0.40) objective releasing a long working distance (WD=5.89mm) by utilizing the Laguerre-Gaussian beams. A series of rotating manipulation through modulating the asymmetry of Laguerre-Gaussian beams are presented. This work offers an extended axial trapping range for 3D manipulation and a delicate hand-actuated rotating system for optical manipulation.