Optical micromanipulation using a Bessel light beam

We demonstrate a technique for optical manipulation of micron-sized particles, including biological samples, using a zeroth-order Bessel light beam. The central maximum of such a beam offers a "non-diffracting" focal line of light. This line focus is well suited to rotationally align rod-like particles along the beam direction and to build stacks of particles. We have stacked up to nine 5 mum spheres above one another and manipulated this particle chain as a whole, Furthermore, we have observed laser guiding (transport) of 1 mum particles along the Bessel beam axis over 1 mm, which is over 10 times the Rayleigh range for a comparable Gaussian beam. (C) 2001 Elsevier Science B.V. All rights reserved.