Acousto-Optic Deflectors

With acousto-optic deflectors (AODs) arbitrary dynamical optical landscapes can be created which allow quasi-simulataneous optical tweezing of up to several hundred particles. This is achieved by deflection of a single incident laser beam on the travelling acoustic wave inside a transparent crystal. Upon changing the frequency and amplitude of this wave, the incoming laser beam can be modulated with respect to its angle and intensity with frequencies up to 50 kHz.


AOD systems are employed in experiments where more than just one laser trap is used, i.e. where extended optical landscapes are created. Since every individual trap can be varied independently with time, this allows to realise complex motional patterns of many colloidal particles. Examples for AOD experiments in our group are Stochastic Resonance, Microfluidics, Ratched Cellular Automata and Giant Diffusion. A simple example of the possibilities and the versatility of AODs is demonstrated in our colloidal soccer game.