Characterization of Bessel beams generated by polymeric microaxicons

We present a quick, simple and accurate digital holographic characterization of the Bessel beams produced by polymeric microaxicons. This technique allows the numerical reconstruction of both intensity and phase of the beam at whichever point starting from a single acquired hologram. From these data, it is possible to go back to the axicon structure, and to gather information about their characteristics. In particular, the focal length and the depth of focus of the axicon lens are experimentally measured, and the full width at half maximum of the beam is obtained too. The depth of focus, very large for a Bessel beam with respect to a Gaussian one, is successfully exploited for optical trapping of micrometric objects.