Determination of the spring constant of an optical trap by external sinusoidal excitation and lock-in detection

We report a method for determining the spring constant of an optical trap by external sinusoidal excitation and lock-in detection. A polystyrene latex particle trapped in a focused Nd:YAG laser beam is forced to oscillate by another intensity-modulated laser-diode beam. Lock-in detection for measuri...

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Bibliographic Details
Published in:Journal of applied physics 2000-07, Vol.88 (2), p.737-741
Main Authors: Ding, Zhihua, Lai, Guanming, Sakakibara, Teruhiko, Shinohara, Shigenobu
Format: Article
Language:English
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Summary:We report a method for determining the spring constant of an optical trap by external sinusoidal excitation and lock-in detection. A polystyrene latex particle trapped in a focused Nd:YAG laser beam is forced to oscillate by another intensity-modulated laser-diode beam. Lock-in detection for measuring particle oscillations is also implemented to obtain the phase delay and amplitude of the harmonic oscillation that correspond to the excitation frequency. Experimental results of trials to determine the spring constant are given to demonstrate the improved precision and reproducibility of our method.
ISSN:0021-8979
1089-7550
DOI:10.1063/1.373730