title: Spatial light modulator-controlled alignment and spinning of birefringent particles optically trapped in an array.
abstract: We demonstrate the use of a phase-only liquid-crystal spatial light modulator (SLM) for polarization-controlled rotation and alignment of an array of optically trapped birefringent particles. A collimated beam incident upon a two-dimensional lenslet array yields multiple foci, scaled to produce optical gradient traps with efficient three-dimensional trapping potentials. The state of polarization of each trapping beam is encoded by the SLM, which acts as a matrix of wave plates with computer-controlled phase retardations. Control of the rotation frequency and alignment direction of the particles is achieved by the transfer of tunable photon spin angular momentum.
authors.affiliation: Optics and Fluid Dynamics Department, Risø National Laboratory, P.O. Box 49, DK-4000 Roskilde, Denmark.
authors.forename: René L
authors.initials: RL
authors.lastname: Eriksen
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Rodrigo
authors.forename: Vincent R
authors.initials: VR
authors.lastname: Daria
authors.forename: Jesper
authors.initials: J
authors.lastname: Glückstad
mesh_terms: D001718:Birefringence; D004867:Equipment Design; D007834:Lasers; D007909:Lenses; D008859:Microscopy, Polarization / Q000295:instrumentation; D055095:Optics and Photonics; D010316:Particle Size