... Manipulation of micrometer scale objects in three dimensions is possible because gradients in the intensity, phase and polarization of computer-generated holograms give rise to forces that can trap and move microscopic matter. These holographic optical tweezers are useful for assembling photonic devices to the possibility of true tractor beams that pull objects back to their source. Holographic optical trapping provides unprecedented control over the microscopic world. Holographic micromanipulation is complemented by holographic video microscopy, which creates volumetric images of three-dimensional systems in real time. ...