Optical trap stiffness in the presence and absence of spherical aberrations

Vermeulen, K.; Wuite, Gijs J. L.; Stienen, G. J. M.; Schmidt, Christoph F.

doi:10.1364/ao.45.001812

Cited by 93 publications

(77 citation statements)

References 32 publications

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“…This is because the fluid friction close to a surface decreases strongly with increasing bead-coverslip separation, which overwhelms the effect of a decreasing axial stiffness. 46,48,53 Beyond 2 μm, the corner frequency starts to decrease with increasing bead-coverslip separation, because in this region the friction becomes a weaker function of beadcoverslip separation, while the axial trapping stiffness continues to decrease. The behavior of the fluid friction near a surface has been explored in detail in Refs.…”

Section: Calibrationmentioning

confidence: 99%

See 1 more Smart Citation

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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Section: Calibrationmentioning

confidence: 99%

“…Such a calibration of axial forces and displacements must take into account a number of effects, including aberrations 45,46 and the interference between the trapping beam and forward-reflected bead-scattered light. 40,47,48 References 41 and 42 have previously used optical traps to apply force in the axial direction.…”

Section: Introductionmentioning

confidence: 99%

Practical axial optical trapping

Mack

Schlingman

Regan

et al. 2012

Review of Scientific Instruments

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show abstract

“…This approach may provide useful rules of thumb for the design of the external setup but it should be noted that important aberrations may be left out of the analysis. For example, when using oilimmersion lenses, the index mismatch at the glass/water interface is known to be a major source of spherical aberration [37]. As our objectives are infinity-corrected, spherical aberration is minimized at the front focal plane.…”

Section: Aberrations In the Optical Trainmentioning

confidence: 99%

Design strategies for optimizing holographic optical tweezers set-ups

Martı́n-Badosa¹,

Montes-Usategui²,

Carnicer³

et al. 2007

J. Opt. A: Pure Appl. Opt.

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Abstract. We provide a detailed account of the construction of a system of holographic optical tweezers. While a lot of information is available on the design, alignment and calibration of other optical trapping configurations, those based on holography are relatively poorly described. Inclusion of a spatial light modulator in the setup gives rise to particular design trade-offs and constraints, and the system benefits from specific optimization strategies, which we discuss.

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“…The laserinduced temperature increase, which occurs within the laser focus, has a significant effect on the measured trap stiffness through its effect on the viscosity of the medium and the thermal motion of the trapped particle. 78,82 This effect becomes more pronounced at higher trapping laser powers and higher trapping depths when using an oil immersion microscope objective. 83 We accounted for these effects by assuming a temperature increase of 8 K∕W at 1064 nm in DI water as our optical trapping medium.…”

Section: Optical Trap Formationmentioning

confidence: 99%

Comparative study of methods to calibrate the stiffness of a single-beam gradient-force optical tweezers over various laser trapping powers

2014

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Abstract. Optical tweezers have become an important instrument in force measurements associated with various physical, biological, and biophysical phenomena. Quantitative use of optical tweezers relies on accurate calibration of the stiffness of the optical trap. Using the same optical tweezers platform operating at 1064 nm and beads with two different diameters, we present a comparative study of viscous drag force, equipartition theorem, Boltzmann statistics, and power spectral density (PSD) as methods in calibrating the stiffness of a single beam gradient force optical trap at trapping laser powers in the range of 0.05 to 1.38 W at the focal plane. The equipartition theorem and Boltzmann statistic methods demonstrate a linear stiffness with trapping laser powers up to 355 mW, when used in conjunction with video position sensing means. The PSD of a trapped particle's Brownian motion or measurements of the particle displacement against known viscous drag forces can be reliably used for stiffness calibration of an optical trap over a greater range of trapping laser powers. Viscous drag stiffness calibration method produces results relevant to applications where trapped particle undergoes large displacements, and at a given position sensing resolution, can be used for stiffness calibration at higher trapping laser powers than the PSD method.

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Optical trap stiffness in the presence and absence of spherical aberrations

Cited by 93 publications

References 32 publications

Practical axial optical trapping

Practical axial optical trapping

Design strategies for optimizing holographic optical tweezers set-ups

Comparative study of methods to calibrate the stiffness of a single-beam gradient-force optical tweezers over various laser trapping powers

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