Optical Tweezers are useful tools for trapping particles with sizes from nanometer to micrometer. This tool can exert forces in the range of femto to nano Newtons to the trapped object. Optical Tweezers have to be calibrated prior to use. Photo-diode detection scheme is the most common calibration method of optical tweezers. This method suffers from nonlinear response for large displacements of the trapped bead. Video-Microscopy is known as another calibration method in which the image of the trapped particle is used for calibration. The main disadvantage of the current method is the limited temporal resolution of the recording camera. In this paper it is shown that recording only a narrow strip of the particle’s image recorded by a fast camera could significantly overcome this limitation of the current calibration method.

Keywords: Optical Tweezers, Calibration, high speed Camera, Photo-Diode, Video-Microscopy

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