Power spectrum analysis for optical tweezers. II: Laser wavelength dependence of parasitic filtering, and how to achieve high bandwidth

Kirstine Berg-Sørensen, Erwin J G Peterman, Tom Weber, Christoph F Schmidt, Henrik Flyvbjerg

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    Abstract

    In a typical optical tweezers detection system, the position of a trapped object is determined from laser light impinging on a quadrant photodiode. When the laser is infrared and the photodiode is of silicon, they can act together as an unintended low-pass filter. This parasicit effect is due to the high transparency of silicon to near-infrared light. A simple model that accounts for this phenomenon is here solved for frequencies up to 100 kHz and for laser wavelengths between 750 and 1064 nm. The solution is applied to experimental data in the same range, and is demonstrated to give this detection system of optical tweezers a bandwidth, accuracy, and precision that are limited only by the data acquisition board's bandwidth and bandpass ripples, here 96.7 kHz and 0.005 dB, respectively. ©2006 American Institute of Physics
    Original languageEnglish
    JournalReview of Scientific Instruments
    Volume77
    Issue number6
    ISSN0034-6748
    DOIs
    Publication statusPublished - 2006

    Bibliographical note

    Copyright (2006) American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics.

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