Extended-area optically induced organization of microparticies on a surface -: art. no. 031106

To extend beyond the limited field of view associated with optical tweezers, we implement a new geometry for lensless optical trapping (LOT). A Ronchi ruling is imaged at a sample interface beyond the critical angle for total internal reflection imposing local structure upon the optical fields. Due to the resulting transverse optical gradients, more than one thousand microparticles spanning 1 mm(2) were organized into microchannels that are entirely optical in origin. A generalized approach is presented, allowing for either guiding or stable trapping, as a function of the relative intensity of the counterpropagating surface waves. (C) 2005 American Institute of Physics. [DOI: 10.1063/1.1843283]