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.

Date Published: 16 September 2014
PDF: 6 pages
Proc. SPIE 9164, Optical Trapping and Optical Micromanipulation XI, 91640A (16 September 2014); doi: 10.1117/12.2061940

Published in SPIE Proceedings Vol. 9164:
Optical Trapping and Optical Micromanipulation XI
Kishan Dholakia; Gabriel C. Spalding, Editor(s)