We report using a fast-shuttering CCD camera to determine the transverse stiffness of an optical tweezers trap. By utilizing the relation between the particle position variance and the trap stiffness we are able to circumvent the sampling requirements of the position power spectrum approach. We find that for trap stiffness of order 10-5 N/m exposures shorter than 0.001 sec seem to be required in order to give valid measurements. For longer exposures (~0.01 sec) the trap stiffness can be overestimated by a factor of three or more.
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机译：我们使用快速快门的CCD相机报告以确定光学镊子陷阱的横向刚度。 通过利用粒子位置方差与陷阱刚度之间的关系，我们能够规避位置功率谱方法的采样要求。 我们发现，对于陷阱刚度，10-5 n / m暴露的曝光率短于0.001秒，似乎是需要的，以便提供有效的测量。 对于更长的曝光（〜0.01秒），捕获刚度可以高估了三个或更多的倍数。
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