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Optics Express

Optics Express

  • Editor: C. Martijn de Sterke
  • Vol. 16, Iss. 7 — Mar. 31, 2008
  • pp: 4420–4425

An adaptive system identification approach to optical trap calibration

Kurt D. Wulff, Daniel G. Cole, and Robert L. Clark  »View Author Affiliations

Optics Express, Vol. 16, Issue 7, pp. 4420-4425 (2008)

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A method of adaptive system identification for the modeling of an optical trap’s system dynamics is presented. The system dynamics can be used to locate the corner frequency for trapping stiffness calibration using the power spectral method. The method is based on an adaptive least-mean-square (LMS) algorithm, which adjusts weights of a tapped delay line filter using a gradient descent method. The identified model is the inverse of the high order finite impulse response (FIR) filter. The model order is reduced using balanced model reduction, giving the corner frequency which can be used to calibrate the trapping stiffness. This method has an advantage over other techniques in that it is quick, does not explicitly require operator interaction, and can be acquired in real time. It is also a necessary step for an adaptive controller that can automatically update the controller for changes in the trap (e.g., power fluctuations) and for particles of different sizes and refractive indices.

© 2008 Optical Society of America

OCIS Codes
(140.7010) Lasers and laser optics : Laser trapping
(180.0180) Microscopy : Microscopy

ToC Category:
Optical Trapping and Manipulation

Original Manuscript: July 18, 2007
Revised Manuscript: December 11, 2007
Manuscript Accepted: December 14, 2007
Published: March 17, 2008

Virtual Issues
Vol. 3, Iss. 4 Virtual Journal for Biomedical Optics

Kurt D. Wulff, Daniel G. Cole, and Robert L. Clark, "An adaptive system identification approach to optical trap calibration," Opt. Express 16, 4420-4425 (2008)

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