Optical tweezing of rod-like particles and hollow spheres in an interference pattern

Summary form only given. We describe and demonstrate for the first time, the alignment and simultaneous manipulation in 2-dimensions of both rod-like particles and hollow spheres, using interference fringes. These fringes were produced by separating a laser beam (Nd:YAG @ 1064 nm, 150 mW) and recombining the resultant beams at the focus of a /spl times/20 microscope objective. The pattern produced consisted of a set of parallel fringes which could be scanned cross the area of the combined spot or moved as a whole around the sample cell. Observations of tweezing were done using a /spl times/100 objective mounted below the sample cell.