Optical trapping for undergraduates

Appleyard, David; Vandermeulen, K. Y.; Lee, H.; Lang, Matthew J.

doi:10.1119/1.2366734

Cited by 55 publications

(39 citation statements)

References 27 publications

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“…The optical trapping system uses a diode-pumped, solid-state Nd:YVO 4 laser operating at a wavelength of 1064 nm. The optical trap is created by tightly focusing the trapping beam, achieved using a microscope objective with a high numerical aperture of 1.30.…”

Section: (B) Optical Set-upmentioning

confidence: 99%

Pushing, pulling and twisting liquid crystal systems: exploring new directions with laser manipulation

Sanders

Yang

Dickinson

et al. 2013

Phil. Trans. R. Soc. A.

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Optical tweezers are exciting tools with which to explore liquid crystal (LC) systems; the motion of particles held in laser traps through LCs is perhaps the only approach that allows a low Ericksen number regime to be accessed. This offers a new method of studying the microrheology associated with micrometre-sized particles suspended in LC media-and such hybrid systems are of increasing importance as novel soft-matter systems. This paper describes the microrheology experiments that are possible in nematic materials and discusses the sometimes unexpected results that ensue. It also presents observations made in the inverse system; micrometre-sized droplets of LC suspended in an isotropic medium.

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Section: (B) Optical Set-upmentioning

confidence: 99%

Pushing, pulling and twisting liquid crystal systems: exploring new directions with laser manipulation

Sanders

Yang

Dickinson

et al. 2013

Phil. Trans. R. Soc. A.

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“…16 Simulations can also complement the use of optical tweezers in undergraduate laboratories. [17][18][19] The associated MATLAB programs are freely available. 20 These MATLAB programs can be straightforwardly adapted to the freeware SCILAB.…”

Section: Introductionmentioning

confidence: 99%

Simulation of a Brownian particle in an optical trap

Volpe

2013

American Journal of Physics

234

196

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An optically trapped Brownian particle is a sensitive probe of molecular and nanoscopic forces. An understanding of its motion, which is caused by the interplay of random and deterministic contributions, can lead to greater physical insight into the behavior of stochastic phenomena. The modeling of realistic stochastic processes typically requires advanced mathematical tools. We discuss a finite difference algorithm to compute the motion of an optically trapped particle and the numerical treatment of the white noise term. We then treat the transition from the ballistic to the diffusive regime due to the presence of inertial effects on short time scales and examine the effect of an optical trap on the motion of the particle. We also outline how to use simulations of optically trapped Brownian particles to gain understanding of nanoscale force and torque measurements, and of more complex phenomena, such as Kramers transitions, stochastic resonant damping, and stochastic resonance. © 2013 American Association of Physics Teachers

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“…12,15,27,28 However, this configuration also has important limitations: dumbbells have to be individually constructed for each single molecule; they require an apparatus with beam steering optics; and the minimum, measurable extension is limited at small extensions by each bead interacting with the other trapping beam. Surface attachment schemes offer a number of practical advantages: first, a range of methods is available to tether large numbers of micron-sized beads to a glass coverslip, [29][30][31][32][33][34] increasing experimental throughput. Then, once beads are tethered, a relatively simple setup, comprised of a translation stage and a stationary optical trap are the only requirements for optical trapping measurements of the force and extension of single molecules.…”

Section: Introductionmentioning

confidence: 99%

Practical axial optical trapping

Mack

Schlingman

Regan

et al. 2012

Review of Scientific Instruments

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We describe a new method for calibrating optical trapping measurements in which tension is applied in the direction of the laser beam to a molecule tethered between a surface and an optically trapped bead. Specifically, we present a generally-applicable procedure for converting from the measured scattering intensity and the measured stage displacement to applied tension and bead-coverslip separation, using measurements of the light intensity scattered from an untethered, trapped bead. Our calibration accounts for a number of effects, including aberrations and the interference of forwardreflected bead-scattered light with the trapping beam. To demonstrate the accuracy of our method, we show measurements of the DNA force-versus-extension relation using a range of laser intensities, and show that these measurements match the expected extensible wormlike-chain (WLC) behavior. Finally, we also demonstrate a force-clamp, in which the tension in a tether is held fixed while the extension varies as a result of molecular events.

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Optical trapping for undergraduates

Cited by 55 publications

References 27 publications

Pushing, pulling and twisting liquid crystal systems: exploring new directions with laser manipulation

Pushing, pulling and twisting liquid crystal systems: exploring new directions with laser manipulation

Simulation of a Brownian particle in an optical trap

Practical axial optical trapping

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