Three-dimensional trapping with a focused Bessel beam

A Bessel beam generated with an axicon lens is focused through a low numerical aperture objective lens to create an optical levitation trap. This configuration allows a full three dimensional trapping of solid glass spheres of few microns in diameter immerse in water. We establish a comparison with an optical levitation trap generated with a Gaussian beam under the same focusing conditions. In both cases the particles are lifted up in an axial position above the focal region that depends on the incident power. The spatial stability is investigated in both cases as a function of axial position, which in turn depends on the input optical power.