title: Calibration of the optical torque wrench.
abstract: The optical torque wrench is a laser trapping technique that expands the capability of standard optical tweezers to torque manipulation and measurement, using the laser linear polarization to orient tailored microscopic birefringent particles. The ability to measure torque of the order of kBT (∼4 pN nm) is especially important in the study of biophysical systems at the molecular and cellular level. Quantitative torque measurements rely on an accurate calibration of the instrument. Here we describe and implement a set of calibration approaches for the optical torque wrench, including methods that have direct analogs in linear optical tweezers as well as introducing others that are specifically developed for the angular variables. We compare the different methods, analyze their differences, and make recommendations regarding their implementations.
authors.affiliation: Department of Bionanoscience, Kavli Institute of Nanoscience, Faculty of Applied Sciences, Delft University of Technology, Lorentzweg 1, 2628 CJ Delft, The Netherlands.
authors.forename: Francesco
authors.initials: F
authors.lastname: Pedaci
authors.forename: Zhuangxiong
authors.initials: Z
authors.lastname: Huang
authors.forename: Maarten
authors.initials: M
authors.lastname: van Oene
authors.forename: Nynke H
authors.initials: NH
authors.lastname: Dekker
mesh_terms: D001718:Birefringence; D002138:Calibration; D004058:Diffusion; D052898:Optical Tweezers; D019415:Torque