Simultaneous micromanipulation in multiple planes using a self-reconstructing light beam
Simultaneous micromanipulation in multiple planes using a self-reconstructing light beam
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DOI：
10.1038/nature01007
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发表时间：
2002-09-12
期刊：
影响因子：
64.8
通讯作者：
Dholakia, K
中科院分区：
文献类型：
--
作者：
Garcés-Chávez, V;McGloin, D;Dholakia, K
光镊(1)通常用于操纵微观粒子，应用于细胞操作(2)、胶体研究（3-5）、微机器操作(6)和光束特性研究(7)。这种镊子的工作原理是将动量从紧密聚焦的激光转移到粒子上，从而使光发生折射和散射，并使光束的轮廓发生扭曲。这个过程产生的力使粒子被困在光束焦点附近。传统的镊子使用高斯光束，由于光束被粒子畸变和随后从焦平面产生的强烈发散，它不能在轴向上相距几微米的多个位置捕获粒子。然而，贝塞尔光束（8,9）不会发散，而且，如果光束的一部分被阻挡或扭曲，光束会在一段特征传播距离（10）后自行重建。在这里，我们展示了如何在光镊中利用这种重构特性来捕获多个空间分离的样品细胞中的粒子。由于贝塞尔光束的无衍射特性，二次捕获的粒子可以驻留在距离第一个细胞很远（类似于3毫米）的第二个样品细胞中。这种镊子可用于同时研究相同制备的胶体和生物物质的集合，并有可能提供对“芯片实验室”和光学驱动微结构的增强控制。
Optical tweezers(1) are commonly used for manipulating microscopic particles, with applications in cell manipulation (2), colloid research(3-5), manipulation of micromachines(6) and studies of the properties of light beams(7). Such tweezers work by the transfer of momentum from a tightly focused laser to the particle, which refracts and scatters the light and distorts the profile of the beam. The forces produced by this process cause the particle to be trapped near the beam focus. Conventional tweezers use gaussian light beams, which cannot trap particles in multiple locations more than a few micrometres apart in the axial direction, because of beam distortion by the particle and subsequent strong divergence from the focal plane. Bessel beams(8,9), however, do not diverge and, furthermore, if part of the beam is obstructed or distorted the beam reconstructs itself after a characteristic propagation distance(10). Here we show how this reconstructive property may be utilized within optical tweezers to trap particles in multiple, spatially separated sample cells with a single beam. Owing to the diffractionless nature of the Bessel beam, secondary trapped particles can reside in a second sample cell far removed (similar to3 mm) from the first cell. Such tweezers could be used for the simultaneous study of identically prepared ensembles of colloids and biological matter, and potentially offer enhanced control of 'lab-on-a-chip' and optically driven microstructures.