Our paper 'Trapping volume control in optical tweezers using cylindrical vector beams' has been published as S. E. Skelton et al, Optics Letters 30 28-30 (2013).
From the abstract: We present the result of an investigation into the optical trapping of
spherical microparticles using laser beams with a spatially
inhomogeneous polarization direction [cylindrical vector beams (CVBs)].
We perform three-dimensional tracking of the Brownian fluctuations in
the position of a trapped particle and extract the trap spring
constants. We characterize the trap geometry by the aspect ratio of
spring constants in the directions transverse and parallel to the beam
propagation direction and evaluate this figure of merit as a function of
polarization angle. We show that the additional degree of freedom
present in CVBs allows us to control the optical trap strength and
geometry by adjusting only the polarization of the trapping beam.
Experimental results are compared with a theoretical model of optical
trapping using CVBs derived from electromagnetic scattering theory in
the T-matrix framework.