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Proceedings Paper

Dynamic analysis of trapping and escaping in dual beam optical trap
Author(s): Wenqiang Li; Huizhu Hu; Heming Su; Zhenggang Li; Yu Shen
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Paper Abstract

In this paper, we simulate the dynamic movement of a dielectric sphere in optical trap. This dynamic analysis can be used to calibrate optical forces, increase trapping efficiency and measure viscous coefficient of surrounding medium. Since an accurate dynamic analysis is based on a detailed force calculation, we calculate all forces a sphere receives. We get the forces of dual-beam gradient radiation pressure on a micron-sized dielectric sphere in the ray optics regime and utilize Einstein-Ornstein-Uhlenbeck to deal with its Brownian motion forces. Hydrodynamic viscous force also exists when the sphere moves in liquid. Forces from buoyance and gravity are also taken into consideration. Then we simulate trajectory of a sphere when it is subject to all these forces in a dual optical trap. From our dynamic analysis, the sphere can be trapped at an equilibrium point in static water, although it permanently fluctuates around the equilibrium point due to thermal effects. We go a step further to analyze the effects of misalignment of two optical traps. Trapping and escaping phenomena of the sphere in flowing water are also simulated. In flowing water, the sphere is dragged away from the equilibrium point. This dragging distance increases with the decrease of optical power, which results in escaping of the sphere with optical power below a threshold. In both trapping and escaping process we calculate the forces and position of the sphere. Finally, we analyze a trapping region in dual optical tweezers.

Paper Details

Date Published: 19 October 2016
PDF: 9 pages
Proc. SPIE 10154, Advanced Optical Design and Manufacturing Technology and Astronomical Telescopes and Instrumentation, 1015415 (19 October 2016); doi: 10.1117/12.2246670
Show Author Affiliations
Wenqiang Li, Zhejiang Univ. (China)
Huizhu Hu, Zhejiang Univ. (China)
Heming Su, Zhejiang Univ. (China)
Zhenggang Li, Zhejiang Univ. (China)
Yu Shen, Zhejiang Univ. of Science and Technology (China)

Published in SPIE Proceedings Vol. 10154:
Advanced Optical Design and Manufacturing Technology and Astronomical Telescopes and Instrumentation
Min Xu; Ji Yang, Editor(s)

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