Implementing both short- and long-working-distance optical trappings into a commercial microscope

Kraikivski, Pavel; Pouligny, B.; Dimova, Rumiana

doi:10.1063/1.2400023

Cited by 24 publications

(17 citation statements)

References 30 publications

(53 reference statements)

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“…We start by examining the absolute localization of particles of different sizes. We find that forr π =0 localization is improved as particle size increases in accord with previous studies [15,24]. As we increaser π the localization of the particles changes, however, the trend of change depends on the size of the trapped particle.…”

Section: Pacs Numberssupporting

confidence: 92%

Optical trapping below the diffraction limit with a tunable beam waist using super-oscillating beams

et al. 2019

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Super-oscillating beams can be used to create light spots whose size is below the diffraction limit with a side ring of high intensity adjacent to them. Optical traps made of the super-oscillating part of such beams exhibit superior localization of submicron beads compared to regular optical traps. Here we focus on the effect of the ratio of particle size to trap size on the localization and stiffness of optical traps made of super-oscillating beams. We find a non-monotonic dependence of trapping stiffness on the ratio of particle size to beam size. Optimal trapping is achieved when the particle is larger than the beam waist of the super-oscillating feature but small enough not to overlap with the side ring. PACS numbers:In the early 70s, Artur Ashkin showed that a weakly focused laser beam can draw small particles with high refractive index towards its center and move them in the direction of light propagation [1]. A major breakthrough in this field happened in 1986 when Ashkin demonstrated the single beam optical gradient force traps [2], known nowadays as optical tweezers. Since then, optical trapping application has become a powerful tool used in physics and biology. However, the size of an optical trap is limited by the smallest spot which collimated light can be focused to using an annular aperture, as discussed in 1873 by Ernst Abbe [3] and later by Lord Rayleigh [4]. The diffraction limit of light determining this minimal beam size is given by w = 0.38λ/NA, where w is the beam waist defined as the full width at half maximum of the beam, λ is the wavelength of the beam, and NA is the numerical aperture of the focusing lens. In 1952 G. Toraldo di Francia suggested theoretically that by phase modulations one can achieve optical features below the diffraction limit [5]. In the 90's the concept of super oscillation (SO) was first introduce by Michel Berry for bandlimited functions that locally oscillate faster than their highest Fourier component [6]. In optics, the SO phenomena was used to generate optical beams with features smaller than the diffraction limit. Over the last 20 years SO beams were generated using different methods [7-9] and applied for super-resolution imaging [10,11].The effect of particle size, beam waist, and wavelength on the stiffness of optical trapping was studied theoretically for different scattering regimes [12][13][14]. Experimental verification of these predictions is challenging since neither beam size, wavelength, nor particle size can be changed continuously to provide a clean comparison [15][16][17][18]. Naturally, all previous measurements focused on diffraction-limited optical traps. Previously, we observed that a significant enhancement of optical trapping strength and localization occurred when a 490 nm particle was trapped in the SO part of a SO beam [19]. Here we study this effect in more detail. We use the unique feature of SO beams, namely, the ability to change continuously the beam waist and to focus the beam to below the diffraction limit, to measure the effect of p...

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Section: Pacs Numberssupporting

confidence: 92%

Optical trapping below the diffraction limit with a tunable beam waist using super-oscillating beams

et al. 2019

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“…The optical tweezers were built around a motorized inverted microscope (Axiovert 200M; Zeiss) by focusing a 1,064-nm, continuous-wave beam from a Nd:YAG laser through a 100×, 1.25 N.A. objective lens ( 51 ). The bead position was determined using centroid tracking algorithm ( 52 ).…”

Section: Methodsmentioning

confidence: 99%

The glycolipid GM1 reshapes asymmetric biomembranes and giant vesicles by curvature generation

Dasgupta

Miettinen

Fricke

et al. 2018

Proc. Natl. Acad. Sci. U.S.A.

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102

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SignificanceThe multifaceted involvement of GM1 as a ligand in many cellular functions has been well recognized. We find that GM1 readily desorbs from the membrane of cell-sized model biomimetic systems (giant unilamellar vesicles). The desorption is unbalanced, creating an asymmetry between the bilayer leaflets. This results in reshaping weakly curved membranes into nanotubular invaginations stabilized by the membrane spontaneous curvature, which we quantify experimentally. Computer simulations confirm the experimental results. Uncovering the role of GM1 as a fine regulator of membrane curvature broadens our perspective on its important function in reshaping neuronal membranes and emphasizes that GM1 desorption can strongly affect the cell membrane morphology.

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“…As detailed by Kraikivski et al, the efficient optical trapping of spherical particles, in liquid water, using counter-propagating laser beams is achieved when the particle radius and the beam waist of the focussed laser beam are of similar size. 36 Fulfilling this condition generates the maximum radiation pressure from each of the focussed laser beams for a given laser power. The stability of counter-propagating traps for small particles is reported to require a small and positive separation between the foci of the two counter propagating beams.…”

Section: Introductionmentioning

confidence: 99%

Optical trapping and Raman spectroscopy of solid particles

Rkiouak

Tang

Camp

et al. 2014

Phys. Chem. Chem. Phys.

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The heterogeneous interactions of gas molecules on solid particles are crucial in many areas of science, engineering and technology. Such interactions play a critical role in atmospheric chemistry and in heterogeneous catalysis, a key technology in the energy and chemical industries. Investigating heterogeneous interactions upon single levitated particles can provide significant insight into these important processes. Various methodologies exist for levitating micron sized particles including: optical, electrical and acoustic techniques. Prior to this study, the optical levitation of solid micron scale particles has proved difficult to achieve over timescales relevant to the above applications. In this work, a new vertically configured counter propagating dual beam optical trap was optimized to levitate a range of solid particles in air. Silica (SiO2), α-alumina (Al2O3), titania (TiO2) and polystyrene were stably trapped with a high trapping efficiency (Q = 0.42). The longest stable trapping experiment was conducted continuously for 24 hours, and there are no obvious constraints on trapping time beyond this period. Therefore, the methodology described in this paper should be of major benefit to various research communities. The strength of the new technique is demonstrated by the simultaneous levitation and spectroscopic interrogation of silica particles by Raman spectroscopy. In particular, the adsorption of water upon silica was investigated under controlled relative humidity environments. Furthermore, the collision and coagulation behaviour of silica particles with microdroplets of sulphuric acid was followed using both optical imaging and Raman spectroscopy.

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Implementing both short- and long-working-distance optical trappings into a commercial microscope

Cited by 24 publications

References 30 publications

Optical trapping below the diffraction limit with a tunable beam waist using super-oscillating beams

Optical trapping below the diffraction limit with a tunable beam waist using super-oscillating beams

The glycolipid GM1 reshapes asymmetric biomembranes and giant vesicles by curvature generation

Optical trapping and Raman spectroscopy of solid particles

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