基于视觉原理的三维光阱刚度测量系统

Measuring System of 3D Trapping Stiffness Based on Vision Theory

光阱刚度是表征光镊捕获微小颗粒能力的重要参数。文中搭建了一套基于视觉原理的三维光阱刚度测量系统。测量系统中采用波长1 064 nm的近红外激光光镊捕获直径2μm的聚苯乙烯微球,采用基于视觉原理的光路对微球成像,由高速摄像机记录微球的布朗运动。对高速摄像机采集的相邻图像进行亚像素的位移提取,获取微球的三维位移,采用功率谱法得到相应的光阱刚度。

The trap stiffness is an important characteristic parameter for optical tweezers to manipulate micro-particles. A system based on vision theory was built to achieve the measurement of 3D trap stiffness.In the measuring system, near-infrared laser whose wavelength is 1 064 nm was used to capture polystyrene mierosphere with diameter of 2 μm, optical system based on vision theory was set up to image the microsphere.The Brownian motion of the mierosphere was recorded by a high-speed camera. The adjacent images taken by high-Speed camera were processed to obtain the 3D displacements of microsphere with sub-pixel accuracy, and the corresponding trap stiffness was achieved by power spectrum method.