Two particle tracking and detection in a single Gaussian beam optical trap

Praveen, P. Lakshmi; Yogesha,; Iyengar, Shruthi S.; Bhattacharya, Sarbari; Ananthamurthy, Sharath

doi:10.1364/ao.55.000585

Cited by 7 publications

(6 citation statements)

References 16 publications

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“…1). The normalized fluctuations of the trapped particle in two orthogonal displacements, along the X and Y axes, in units of volts, are given by [25]…”

Section: Results and Discussion A Fluctuation Behavior Of A Trapped Probe In The Xy Planementioning

confidence: 99%

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Trap stiffness modification of an optically trapped microsphere through directed motion of nanoparticles

et al. 2020

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We report an enhancement in the corner frequency of an optically trapped non-magnetic microsphere in the plane perpendicular to the laser propagation direction on addition of ferrofluid to the suspension medium. We conjecture that a directed motion of the nanoparticles toward the trap in this plane is responsible for the augmentation. Changes in the corner frequency in the presence of external magnetic field gradients lend credence to this conjecture. Corner frequency augmentation is also observed when zinc oxide nanoparticles are used. Here, however, no further changes are seen in the presence of magnetic field gradients.

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“…1). The normalized fluctuations of the trapped particle in two orthogonal displacements, along the X and Y axes, in units of volts, are given by [25]…”

Section: Results and Discussion A Fluctuation Behavior Of A Trapped Probe In The Xy Planementioning

confidence: 99%

“…We have used the calibration method outlined in Refs. [17,25] to obtain the calibration factor to convert the fluctuations obtained in voltages to displacements.…”

Section: Results and Discussion A Fluctuation Behavior Of A Trapped Probe In The Xy Planementioning

confidence: 99%

Trap stiffness modification of an optically trapped microsphere through directed motion of nanoparticles

et al. 2020

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“…In an earlier work 6 , we have shown that, in an axial two-bead trap, back scattering detection yields position fluctuation information of only the bead the laser encounters first whereas in forward scattering based detection schemes, the fluctuation information from both beads which we call the information crosstalk is present. This crosstalk ridden signal has a dominant contribution from the bead the laser encounters first on its propagation path 6 . Thus, a two laser wavelength simultaneous back scattering scheme allows for recording true fluctuation information of the two axially trapped beads in a SGBOT.…”

Section: Introductionmentioning

confidence: 88%

Probing the interaction between two microspheres in a single Gaussian beam optical trap

Praveen

Iyengar

Lakkegowda³

et al. 2016

SPIE Proceedings

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Interactionsbetween trapped microspheres have been studied in two geometries so far: (i) using line optical tweezers and (ii) in traps using two counter propagating laser beams. In both trap geometries, the stable inter bead separations have been attributed to optical binding. One could also trap two such beads in a single beam Gaussian laser trap. While there are reports that address this configuration through theoretical or simulation based treatments, there has so far been no detailed experimental work that measures the interactions.In this work, we have recorded simultaneously the fluctuation spectra of two beads trapped along the laser propagation direction in a single Gaussian beam trap by measuring the back scattered signal from the trapping and a tracking laser beam that are counter propagating . The backscattering from the trapping laser monitors the bead encountered earlier in the propagation path. The counter propagating tracking laser, on the other hand, is used to monitor the fluctuations of the second bead. Detection is by using quadrant photo detectors placed at either end. The autocorrelation functions of both beads reveal marked departures from that obtained when there is only one bead in the trap. Moreover, the fall-off profiles of the autocorrelation indicates the presence of more than one relaxation time. This indicates a method of detecting the presence of a second bead in a trap without directly carrying out measurements on it. Further, a careful analysis of the relaxation times could also reveal the nature of interactions between the beads.

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“…resulting, as we will show, in the time oscillations of the light transmittance through the waveguide. Index j = L, R enumerates the particle positioned on the left or on the right from the immobile center, m = ρad 2 is the particle mass (ρ is the material density), and 6πηd is the linear drag coefficient for a particle in a medium of viscosity η [26,27]. In what follows we choose the dielectric constant of the slab ǫ = 4 (glass), its width a = d/2, and zero initial velocity.…”

Section: Dynamics Of a Single Particle In The Presence Of A Scatterin...mentioning

confidence: 99%

“…where f j is the dimensionless force acting on the j-th particle [26], and γ is expressed in the physical units as…”

Section: Dynamics Of a Single Particle In The Presence Of A Scatterin...mentioning

confidence: 99%

Temporal oscillations of light transmission through dielectric microparticles subjected to optically induced motion

Sadreev

Sherman

2016

Phys. Rev. A

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We consider light-induced binding and motion of dielectric microparticles in an optical waveguide that gives rise to a back-action effect such as light transmission oscillating with time. Modeling the particles by dielectric slabs allows us to solve the problem analytically and obtain a rich variety of dynamical regimes both for Newtonian and damped motion. This variety is clearly reflected in temporal oscillations of the light transmission. The characteristic frequencies of the oscillations are within the ultrasound range of the order of 10 5 Hz for micron size particles and injected power of the order of 100 mW. In addition, we consider driven by propagating light dynamics of a dielectric particle inside a Fabry-Perot resonator. These phenomena pave a way for optical driving and monitoring of motion of particles in waveguides and resonators.

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Two particle tracking and detection in a single Gaussian beam optical trap

Cited by 7 publications

References 16 publications

Trap stiffness modification of an optically trapped microsphere through directed motion of nanoparticles

Trap stiffness modification of an optically trapped microsphere through directed motion of nanoparticles

Probing the interaction between two microspheres in a single Gaussian beam optical trap

Temporal oscillations of light transmission through dielectric microparticles subjected to optically induced motion

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