Rogers W Benjamin, Crocker John C
Department of Chemical and Biomolecular Engineering, University of Pennsylvania, 220 S. 33rd Street, Philadelphia, Pennsylvania 19104-6393, USA.
Rev Sci Instrum. 2014 Apr;85(4):043704. doi: 10.1063/1.4870806.
We describe a simple scanning-line optical tweezers instrument for measuring pair interactions between micrometer-sized colloidal particles. Our instrument combines a resonant scanning mirror and an acousto-optic modulator. The resonant scanning mirror creates a time-averaged line trap whose effective one-dimensional intensity profile, and corresponding trapping potential energy landscape can be programmed using the acousto-optic modulator. We demonstrate control over the confining potential by designing and measuring a family of one-dimensional harmonic traps. By adjusting the spring constant, we balance scattering-induced repulsive forces between a pair of trapped particles, creating a flat potential near contact that facilitates interaction measurements. We also develop a simple method for extracting the out-of-plane motion of trapped particles from their relative brightness, allowing us to resolve their relative separation to roughly 1 nm.
我们描述了一种用于测量微米级胶体颗粒之间成对相互作用的简单扫描线光镊仪器。我们的仪器结合了一个共振扫描镜和一个声光调制器。共振扫描镜创建了一个时间平均线阱，其有效的一维强度分布以及相应的捕获势能景观可以通过声光调制器进行编程。我们通过设计和测量一系列一维谐波阱来展示对限制势的控制。通过调整弹簧常数，我们平衡了一对捕获粒子之间由散射引起的排斥力，在接触附近创建了一个平坦的势，这有利于相互作用测量。我们还开发了一种简单的方法，通过捕获粒子的相对亮度来提取其平面外运动，使我们能够将它们的相对间距解析到大约1纳米。
