Controlling soft matter with intermediate-plane holography*

We introduce an approach to phase-only holography that substantially improves the ability of holographic trapping systems to project propagation-invariant modes of light. This technique, which we call intermediate-plane holography, improves the diffraction efficiency of phase-only holograms by up to 400 times, and extends the range of non-diffracting propation by up to a factor of 1000. The resulting holograms are particularly well suited for projecting accelerating modes of light and long-range tractor beams for transporting colloidal particles and aerosols. We present meter-class tractor beams projected with centimeter-scale optical elements.