Momentum measurements with holographic optical tweezers for exploring force detection capabilities on irregular samples

Abstract

We show how measurements of forces through the analysis of light momentum changes can be combined with holographic optical tweezers (HOTs) to leverage the potential of this force detection method. As the magnitude is not derived from the sample displacement, no in situ calibration is required, and measurements are not restricted to specific conditions. In particular, we show that forces on irregular particles and beams can also be measured with optical traps by simultaneously applying a force in the same direction to multiple holographically-trapped particles through a constant flow. Finally, we measure forces exerted on micro-cylinders in order to assess their transversal and longitudinal drag coefficients.