Independent polarisation control of multiple optical traps

We present a system which uses a single spatial light modulator to control the spin angular momentum of multiple optical traps. These traps may be independently controlled both in terms of spatial location and in terms of their spin angular momentum content. The system relies on a spatial light modulator used in a "split-screen" configuration to generate beams of orthogonal polarisation states which are subsequently combined at a polarising beam splitter. Defining the phase difference between the beams with the spatial light modulator enables control of the polarisation state of the light. We demonstrate the functionality of the system by controlling the rotation and orientation of birefringent vaterite crystals within holographic optical tweezers

Optically controlled three-dimensional rotation of microscopic objects

An approach of optically controlled three-dimensional rotation of microscopic objects was studied. A spatially light modulator was used to create a pair of closely separated optical traps holding different parts of the same object. The pair of traps can be made revolve around each other in any plane, rotating the trapped object with them. The method has implications in the positioning and control of miniature components within the optically-driven micromachines