Implementing laser beams possessing desired spatial structure can provide a potential to control optical forces of
optical tweezers in the trapping of micro and nanoparticles. Cylindrical vector beams, in particular, are good candidates due to
their exotic optical features. For instance, a radially polarized beam generates a focus volume about 30 percent smaller than
that of a Gaussian beam. Here, we experimentally study the optical trapping stiffness for both cases of micro- and nanometer
particles. The results for 2.1-micron polystyrene beads show that the trapping force in the axial direction is ~3 times stronger
for the radial polarization than that of a linear polarized beam. Finally, we show that such improvement in trapping depends on
the size of the trapped particle.