Simultaneous calibration of optical tweezers spring constant and position detector response

Gall, Antoine Le; Perronet, Karen; Dulin, David; Villing, André; Bouyer, Philippe; Visscher, Koen; Westbrook, Nathalie

doi:10.1364/oe.18.026469

Cited by 26 publications

(24 citation statements)

References 11 publications

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“…The slope reported is the mean obtained by fitting to slightly different regions of the dispersion signal with the error being dominated by the standard deviation of the mean. For comparison, the sensitivity figure reported by Le Gall et al 18 for the QPD used in their set-up is 0.512 ± 0.013 µm −1 at 1064 nm. Now, the minimum displacement ∆x min resolvable is ∆x min = ∆y min Slope…”

Section: Measurements Using Aodmentioning

confidence: 86%

Measurement of probe displacement to the thermal resolution limit in photonic force microscopy using a miniature quadrant photodetector

Pal

Haldar

Roy

et al. 2012

Review of Scientific Instruments

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A photonic force microscope comprises of an optically trapped micro-probe and a position detection system to track the motion of the probe. Signal collection for motion detection is often carried out using the backscattered light off the probe -however, this mode has problems of low S/N due to the small backscattering cross-sections of the micro-probes typically used. The position sensors often used in these cases are quadrant photodetectors. To ensure maximum sensitivity of such detectors, it would help if the detector size matched with the detection beam radius after the condenser lens (which for backscattered detection would be the trapping objective itself). To suit this condition, we have used a miniature displacement sensor whose dimensions makes it ideal to work with 1:1 images of micron-sized trapped probes in the back-scattering detection mode. The detector is based on the quadrant photo-IC in the optical pick-up head of a compact disc player. Using this detector, we measured absolute displacements of an optically trapped 1.1 µm probe with a resolution of ∼10 nm for a bandwidth of 10 Hz at 95% significance without any sample or laser stabilization. We characterized our optical trap for different sized probes by measuring the power spectrum for each probe to 1% accuracy, and found that for 1.1 µm diameter probes, the noise in our position measurement matched the thermal resolution limit for averaging times up to 10 ms. We also achieved a linear response range of around 385 nm with crosstalk between axes 4% for 1.1 µm diameter probes. The detector has extremely high bandwidth (few MHz) and low optical power threshold -other factors that can lead to it's widespread use in photonic force microscopy.

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Section: Measurements Using Aodmentioning

confidence: 86%

Measurement of probe displacement to the thermal resolution limit in photonic force microscopy using a miniature quadrant photodetector

Pal

Haldar

Roy

et al. 2012

Review of Scientific Instruments

View full text Add to dashboard Cite

show abstract

“…As in the power-spectrum method, the viscosity and the bead radius are required in addition to the velocity v of the fluid relative to the bead. The principle of the step-response method is to abruptly displace the trap and observe the response as the bead moves back into equilibrium towards the center of the trap 26 . The restoring motion is described by a characteristic time constant τ that can be related to the trap stiffness.…”

Section: Common Methods For the Calibration Of Optical Tweezersmentioning

confidence: 99%

“…The optical set-up has been described elsewhere 26 . Briefly, it is built using an inverted microscope (Olympus IX70) and an oil-immersion objective (Olympus PlanApo 60X, NA = 1.45).…”

Section: Experimental Setup and Methodsmentioning

confidence: 99%

“…The most commonly employed techniques are the equipartition method 21 and the power-spectrum method [22][23] . Alternative methods have been proposed, such as the drag-force method 24 , the escape-force method 25 , and the stepresponse method 26 . Moreover, two-beam approaches have been introduced using one laser beam to trap the bead and a second low-power one to measure its displacement inside the trap 27 .…”

Section: Introductionmentioning

confidence: 99%

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Optical tweezers calibration with Bayesian inference

et al. 2014

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We present a new method for calibrating an optical-tweezer setup that is based on Bayesian inference 1 . This method employs an algorithm previously used to analyze the confined trajectories of receptors within lipid rafts 2,3 . The main advantages of this method are that it does not require input parameters and is insensitive to systematic errors like the drift of the setup. Additionally, it exploits a much larger amount of the information stored in the recorded bead trajectory than standard calibration approaches. The additional information can be used to detect deviations from the perfect harmonic potential or detect environmental influences on the bead. The algorithm infers the diffusion coefficient and the potential felt by a trapped bead, and only requires the bead trajectory as input. We demonstrate that this method outperforms the equipartition method and the power-spectrum method in input information required (bead radius and trajectory length) and in output accuracy. Furthermore, by inferring a higher order potential our method can reveal deviations from the assumed second-order potential. More generally, this method can also be used for magnetic-tweezer calibration.

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“…Under this approach, either the trapping chamber is moved against a fixed optical trap or calibrated movements are applied to a steerable trapped particle within the trapping chamber. [5][6][7][8][9][10][53][54][55][56][57] In the second (passive) stiffness calibration category, several calibration methods exist to estimate the stiffness of the optical tweezers by analyzing the thermal fluctuations of the trapped particle. 58 Position variance of a trapped particle is used to calculate the optical tweezers stiffness by modeling the behavior of the particle using the equipartition theorem.…”

Section: Introductionmentioning

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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Simultaneous calibration of optical tweezers spring constant and position detector response

Cited by 26 publications

References 11 publications

Measurement of probe displacement to the thermal resolution limit in photonic force microscopy using a miniature quadrant photodetector

Measurement of probe displacement to the thermal resolution limit in photonic force microscopy using a miniature quadrant photodetector

Optical tweezers calibration with Bayesian inference

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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