A Simple Approach to Optical Trapping Analysis

Optical tweezers provide a noninvasive approach for detecting pico-newton forces with nanometer level spatial resolutions [1]. We have developed a simplified model of an optically trapped micron-sized particle using a modified version of a numerical approach [2]. The equations of motion associated with the model assume a low Reynolds number and the stochastically simulated bead behavior is carried out in two dimensions. The passive power spectrum analysis and equipartition theorem analysis confirm the agreement between simulated and experimental data. Based on the experimental and simulation analysis this simple approach can be used to gain information about bead's confining environment such as local temperature and viscosity.
[1] A. Ashkin, J. M. Dziedzic, J. E. Bjorkholm, and Steven Chu, Optics Letters Vol. 11, Issue 5, pp. 288-290 (1986) .
[2] G. Volpe and G Volpe, Am. J. Phys. 81 (3), March 2013.