Three-dimensional force measurements in optical tweezers formed with high-NA micromirrors

摘要

The three-dimensional trap stiffness of optical tweezers formed with high-NA micromirrors is investigated by back-focal-plane interferometry and power spectrum analysis. Normalized stiffness values of (kappa)_(xy)/P_(trap)velence1.2((mu)N/m)/mW and (kappa)_(z)/P_(trap)velence0.52((mu)N/m)/mW in the transverse and axial directions, respectively, have been measured for polystyrene spheres with a radius of 1.03 (mu)m. Compared with high-NA microscope objectives, micromirrors achieve much better trapping performances, particularly in the axial direction.