Increasing Trap Stiffness with Position Clamping in Holographic Optical Tweezers

Darryl Preece, Richard Bowman, Anna Linnenberger, Graham Gibson, Steven Serati, and Miles Padgett

Published by the Optical Society of America Optics Express Vol. 17, Issue 25, pp. 22718-22725 (2009)


We present a holographic optical tweezers system capable of position clamping multiple particles. Moving an optical trap in response to the trapped object’s motion is a powerful technique for optical control and force measurement. We have now realised this experimentally using a Boulder Nonlinear Systems Spatial Light Modulator (SLM) with a refresh rate of 203Hz. We obtain a reduction of 44% in the variance of the bead’s position, corresponding to an increase in effective trap stiffness of 77%. This reduction relies on the generation of holograms at high speed. We present software capable of calculating holograms in under 1ms using a graphics processor unit.

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