Bustamante Carlos, Chemla Yann R, Moffitt Jeffrey R
Cold Spring Harb Protoc. 2009 Oct;2009(10):pdb.ip73. doi: 10.1101/pdb.ip73.
Optical traps or "optical tweezers" have become an indispensable tool in understanding fundamental biological processes. In this article, we present the design of a high-resolution optical tweezers, which is designed to minimize sensitivity to environmental noise. When the tether is attached to a stage, resolution is typically limited by drift and fluctuations in the relative position of the stage and trap-forming objective, cued by environmental noise. In a dual-trap design, however, the biological system is decoupled entirely from the stage by utilizing two optical traps to hold both ends of the tether. By holding each end of the molecule in an identical fashion, such dual-trap optical tweezers are less sensitive to drift and fluctuations of mechanical components. In our instrument, we form two traps from two orthogonally polarized beams generated by a single laser. As a result, many optical components and much of the optical path traveled are common to both trapping beams, thus minimizing differential movements of one optical trap relative to the other. Additionally, this economical use of optics creates an instrument that is simple and compact, reducing the number of elements susceptible to environmental fluctuations.
光学阱或“光镊”已成为理解基本生物过程中不可或缺的工具。在本文中，我们展示了一种高分辨率光镊的设计，其旨在将对环境噪声的敏感度降至最低。当系链连接到载物台时，分辨率通常受载物台与形成阱的物镜相对位置的漂移和波动限制，而这些是由环境噪声引起的。然而，在双阱设计中，通过利用两个光阱固定系链的两端，生物系统与载物台完全解耦。通过以相同方式固定分子的两端，这种双阱光镊对机械部件的漂移和波动不太敏感。在我们的仪器中，我们利用由单个激光器产生的两束正交偏振光束形成两个阱。因此，许多光学元件以及两束捕获光束所经过的大部分光路是共用的，从而使一个光阱相对于另一个光阱的差异移动最小化。此外，这种对光学元件的经济利用打造出了一种简单紧凑的仪器，减少了易受环境波动影响的元件数量。
