Simultaneous optical trapping and imaging in the axial plane: a review of current progress

Yansheng Liang, Shaohui Yan, Zhaojun Wang, Runze Li, Yanan Cai, Minru He, Baoli Yao and Ming Lei

Optical trapping has become a powerful tool in numerous fields such as biology, physics, chemistry, etc. In standard optical trapping systems, trapping and imaging shares the same objective lens, confining the region of observation to the focal plane. To capture optical trapping processes occurring in other plane, especially the axial plane, many methods have been proposed to achieve this goal. Here, we review the methods of acquiring the axial-plane information from which axial plane trapping is observed and discuss their advantages and limitations. To overcome the limitations existing in these methods, we developed an optical tweezer system that allows for simultaneous optical trapping and imaging technique. The versatility and usefulness of the system in axial-plane trapping and imaging is demonstrated by investigating its trapping performance with various optical fields, including Bessel, Airy and snake-like beams. The potential applications of the proposed technique are suggested to several fields, including optical pulling, longitudinal optical binding, tomographic phase microscopy and superresolution microscopy.

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