| Abstrakt: |
Abstract: The stiffness of a single optical trap is a basic parameter of optical manipulators and detecting the displacement of trapped object belongs to fundamental measuremets [1]. The trap stiffness can be determined by position measurements of oscillating (with high frequency) dielectric microsphere. Usually the signal is captured by simple detector like quadrant photodiode [2]. However, this method is hard to apply when working in multitrap mode, especially in case of holographic otical tweezers. In multitrap mode, widely used method is video image processing focused on determining the center of mass of an object [3]. In this contribution we present the method for position measurement based on video sequence analysis from fast camera. The position is obtained by corelating the video frame with templates of known positions of that object. This algorithm can work on several object, finding thei positions independently. It has also scalable accuracy up to sub-pixel level. |
