论文标题
通常适用于光学捕获颗粒的全息扭矩测量
Generally applicable holographic torque measurement for optically trapped particles
论文作者
论文摘要
我们提出了一种测量施加到位于光学陷阱中的任意形状颗粒的光学扭矩的方法，这是根据粒子诱导的光动量的变化来推断的。所有扭矩组件都可以从摄像机在高NA冷凝器的后焦平面记录的单个干扰模式中确定，该模式收集了所有正向散射光。我们得出明确的表达式，将该平面中测得的复杂场映射到扭矩成分。所需的阶段是通过迭代算法检索的，使用光学陷阱的已知位置作为约束。与单个颗粒有关的扭矩以及总扭矩的单独旋转或轨道部分。
We present a method to measure the optical torque applied to particles of arbitrary shape held in an optical trap, inferred from the change of angular momentum of light induced by the particle. All torque components can be determined from a single interference pattern recorded by a camera in the back focal plane of a high-NA condenser collecting all forward scattered light. We derive explicit expressions mapping the measured complex field in this plane to the torque components. The required phase is retrieved by an iterative algorithm, using the known position of the optical traps as constraints. The torque pertaining to individual particles is accessible, as well as separate spin or orbital parts of the total torque.
