ORCID Profile
0000-0002-8332-2309
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Publisher: Informa UK Limited
Date: 10-03-2011
Publisher: American Physical Society (APS)
Date: 21-02-2006
Publisher: Springer Science and Business Media LLC
Date: 03-2001
DOI: 10.1007/PL00004056
Publisher: American Institute of Aeronautics and Astronautics (AIAA)
Date: 06-1998
DOI: 10.2514/2.479
Publisher: MDPI AG
Date: 17-05-2021
DOI: 10.3390/MI12050570
Abstract: The trap stiffness us the key property in using optical tweezers as a force transducer. Force reconstruction via maximum-likelihood-estimator analysis (FORMA) determines the optical trap stiffness based on estimation of the particle velocity from statistical trajectories. Using a modification of this technique, we determine the trap stiffness for a two micron particle within 2 ms to a precision of ∼10% using camera measurements at 10 kfps with the contribution of pixel noise to the signal being larger the level Brownian motion. This is done by observing a particle fall into an optical trap once at a high stiffness. This type of calibration is attractive, as it avoids the use of a nanopositioning stage, which makes it ideal for systems of large numbers of particles, e.g., micro-fluidics or active matter systems.
Publisher: Elsevier BV
Date: 09-2009
Publisher: The Optical Society
Date: 12-08-2014
DOI: 10.1364/OL.39.004827
Publisher: American Physical Society (APS)
Date: 16-02-2022
Publisher: SPIE
Date: 31-08-2006
DOI: 10.1117/12.680114
Publisher: Elsevier BV
Date: 03-2020
Publisher: American Physical Society (APS)
Date: 14-05-2004
Publisher: SPIE
Date: 28-12-2005
DOI: 10.1117/12.651757
Publisher: Springer Science and Business Media LLC
Date: 25-06-2015
DOI: 10.1038/SREP11501
Abstract: Optogenetics uses light to control and observe the activity of neurons, often using a focused laser beam. As brain tissue is a scattering medium, beams are distorted and spread with propagation through neural tissue and the beam’s degradation has important implications in optogenetic experiments. To address this, we present an analysis of scattering and loss of intensity of focused laser beams at different depths within the brains of zebrafish larvae. Our experimental set-up uses a 488 nm laser and a spatial light modulator to focus a diffraction-limited spot of light within the brain. We use a combination of experimental measurements of back-scattered light in live larvae and computational modelling of the scattering to determine the spatial distribution of light. Modelling is performed using the Monte Carlo method, supported by generalised Lorenz–Mie theory in the single-scattering approximation. Scattering in areas rich in cell bodies is compared to that of regions of neuropil to identify the distinct and dramatic contributions that cell nuclei make to scattering. We demonstrate the feasibility of illuminating in idual neurons, even in nucleus-rich areas, at depths beyond 100 μm using a spatial light modulator in combination with a standard laser and microscope optics.
Publisher: IOP Publishing
Date: 03-11-2022
Abstract: A circularly polarized focussed Gaussian beam carries total angular momentum of ℏ per photon about the beam axis, but less than ℏ spin per photon, due to the focussing of the beam. The remainder of the angular momentum is carried as orbital angular momentum. When such beams are used to rotate microscopic birefringent particles in optical tweezers, the change in angular momentum can be optically measured. However, this measurement is made using the collimated transmitted beam, rather than the focussed beam. Therefore, the conversion of spin to orbital angular momentum by focussing or collimating the beam is expected to affect the measurement. We show that for the typical cases where rotating optical tweezers are used for such measurements, the error due to spin–orbit conversion is unimportant, but there exist cases where a spin-only torque measurement would be completely erroneous.
Publisher: SPIE
Date: 28-12-2005
DOI: 10.1117/12.651755
Publisher: Springer Science and Business Media LLC
Date: 04-12-2011
Publisher: American Chemical Society (ACS)
Date: 23-09-2005
DOI: 10.1021/JP054565Z
Abstract: Monodisperse 1-2 nm silicon nanocrystals are synthesized in reverse micelles and have their surfaces capped with either allylamine or 1-heptene to produce either hydrophilic or hydrophobic silicon nanocrystals. Optical characterization (absorption, PL, and time-resolved PL) is performed on colloidal solutions with the two types of surface-capped silicon nanocrystals with identical size distributions. Direct evidence is obtained for the modification of the optical properties of silicon nanocrystals by the surface-capping molecule. The two different surface-capped silicon nanocrystals show remarkably different optical properties.
Publisher: SPIE
Date: 31-08-2006
DOI: 10.1117/12.678953
Publisher: Elsevier BV
Date: 10-2014
Publisher: SPIE
Date: 28-12-2005
DOI: 10.1117/12.651754
Publisher: SPIE-Intl Soc Optical Eng
Date: 2006
DOI: 10.1117/1.2161172
Abstract: We report on a new experimental technique suitable for measurement of light-activated processes, such as fluorophore transport. The usefulness of this technique is derived from its capacity to decouple the imaging and activation processes, allowing fluorescent imaging of fluorophore transport at a convenient activation wavelength. We demonstrate the efficiency of this new technique in determination of the action spectrum of the light mediated transport of rhodamine 123 into the parasitic protozoan Giardia duodenalis.
Publisher: Elsevier
Date: 1998
Publisher: SPIE
Date: 31-08-2006
DOI: 10.1117/12.680187
Publisher: The Optical Society
Date: 07-08-2014
DOI: 10.1364/OE.22.019692
Publisher: Elsevier BV
Date: 06-2003
Publisher: Optica Publishing Group
Date: 2008
DOI: 10.1364/OE.16.001405
Abstract: We propose and investigate a technique for generating smooth two-dimensional potentials for ultra-cold atoms based on the rapid scanning of a far-detuned laser beam using a two-dimensional acousto-optical modulator (AOM). We demonstrate the implementation of a feed-forward mechanism for fast and accurate control of the spatial intensity of the laser beam, resulting in improved homogeneity for the atom trap. This technique could be used to generate a smooth toroidal trap that would be useful for static and dynamic experiments on superfluidity and persistent currents with ultra-cold atoms.
Publisher: Springer Science and Business Media LLC
Date: 09-1992
DOI: 10.1007/BF01588597
Publisher: American Physical Society (APS)
Date: 21-03-2012
Publisher: American Physical Society (APS)
Date: 10-09-2003
Publisher: Optica Publishing Group
Date: 08-2003
DOI: 10.1364/AO.42.004445
Abstract: Holographic interferometry measurements have been performed on high-speed, high-temperature gas flows with a laser output tuned near a resonant sodium transition. The technique allows the detection and quantification of the sodium concentration in the flow. By controlling the laser detuning and seeded sodium concentration, we performed flow visualization in low-density flows that are not normally detectable with standard interferometry. The technique was also successfully used to estimate the temperature in the boundary layer of the flow over a flat plate.
Publisher: SPIE
Date: 10-02-2011
DOI: 10.1117/12.886221
Publisher: SPIE
Date: 23-04-2012
DOI: 10.1117/12.920057
Publisher: American Physical Society (APS)
Date: 18-10-2006
Publisher: Wiley
Date: 20-03-2019
Abstract: Exploring the rheological properties of intracellular materials is essential for understanding cellular and subcellular processes. Optical traps have been widely used for physical manipulation of micro and nano objects within fluids enabling studies of biological systems. However, experiments remain challenging as it is unclear how the probe particle's mobility is influenced by the nearby membranes and organelles. We use liposomes (unilamellar lipid vesicles) as a simple biomimetic model of living cells, together with a trapped particle rotated by optical tweezers to study mechanical and rheological properties inside a liposome both theoretically and experimentally. Here, we demonstrate that this system has the capacity to predict the hydrodynamic interaction between three-dimensional spatial membranes and internal probe particles within submicron distances, and it has the potential to aid in the design of high resolution optical micro/nanorheology techniques to be used inside living cells.
Publisher: American Chemical Society (ACS)
Date: 05-08-2009
DOI: 10.1021/NN900296Q
Abstract: We report on the observation of an intermediate state in the blinking of single CdSe/CdS core-shell nanocrystals. This state has a low quantum yield and connects the "on" and "off" states commonly observed in the photoluminescence blinking of in idual nanocrystals. We find that the transitions between these two emitting states follow nearly single-exponential statistics. The transitions from the "on" state to this intermediate state result from changes in the surface passivation of the nanocrystal. The data are consistent with photoinduced, adsorption/desorption events that take place at the surface of the nanocrystals. The trion state leads to a reduction in photoluminescence in nanocrystals.
Publisher: American Institute of Aeronautics and Astronautics (AIAA)
Date: 06-1998
DOI: 10.2514/2.478
Publisher: SPIE
Date: 28-12-2005
DOI: 10.1117/12.651760
Publisher: Optica Publishing Group
Date: 08-01-2008
DOI: 10.1364/OL.33.000122
Abstract: It has been suggested that radially polarized beams can be used to improve the performance of optical tweezers, with reduced scattering force resulting from both the polarization and the dark center of the beam [Opt. Lett. 32, 1839 (2007)]. We calculate the forces on particles in such traps, using rigorous electromagnetic theory, comparing the results with azimuthally polarized beam, circularly polarized LG 01 beams, and Gaussian beams. Our results agree qualitatively with Opt. Lett. 32, 1839 (2007), but differ quantitatively.
Publisher: American Physical Society (APS)
Date: 26-10-2007
Publisher: SPIE
Date: 03-08-1998
DOI: 10.1117/12.317715
Publisher: Elsevier BV
Date: 12-2001
Publisher: The Optical Society
Date: 08-09-2015
DOI: 10.1364/OE.23.024317
Publisher: Springer Science and Business Media LLC
Date: 02-05-2013
DOI: 10.1038/SREP01759
Publisher: SPIE
Date: 18-10-2004
DOI: 10.1117/12.556730
Publisher: Optica Publishing Group
Date: 11-1997
DOI: 10.1364/AO.36.008128
Abstract: A new variation of holographic interferometry has been utilized to perform simultaneous two-wavelength measurements, allowing quantitative analysis of the heavy particle and electron densities in a superorbital facility. An air test gas accelerated to 12 km/s was passed over a cylindrical model, simulating reentry conditions encountered by a space vehicle on a superorbital mission. Laser beams with two different wavelengths have been overlapped, passed through the test section, and simultaneously recorded on a single holographic plate. Reconstruction of the hologram generated two separate interferograms at different angles from which the quantitative measurements were made. With this technique, a peak electron concentration of (5.5 +/- 0.5) x 10(23) m(-3) was found behind a bow shock on a cylinder.
Publisher: Elsevier
Date: 2007
Publisher: American Physical Society (APS)
Date: 08-04-2010
Publisher: Optica Publishing Group
Date: 03-2007
DOI: 10.1364/AO.46.001554
Abstract: The refractive index of novel organosilica (nano/micro) material is determined using two methods. The first method is based on analysis of optical extinction efficiency of organosilica beads versus wavelength, which is obtained by a standard laboratory spectrometer. The second method relies on the measurable trapping potential of these beads in the focused light beam (laser tweezers). Polystyrene beads were used to test these methods, and the determined dispersion curves of refractive-index values have been found accurate. The refractive index of organosilica beads has been determined to range from 1.60 to 1.51 over the wavelength range of 300-1100 nm.
Publisher: SPIE
Date: 12-02-2009
DOI: 10.1117/12.814357
Publisher: American Chemical Society (ACS)
Date: 03-09-2009
DOI: 10.1021/LA901532X
Abstract: This paper reports on the synthesis of birefringent vaterite microspheres with narrow size distribution using a seeded growth method. In a post-treatment the microspheres were stabilized and functionalized through coating with a combination of organosilica and silica. The coating vastly enhanced the stability of the vaterite microspheres in biological buffers and allowed the attachment of biomolecules such as DNA or proteins. As an ex le, streptavidin was attached to the surface of the functionalized microspheres. These results pave the way for the use of birefringent vaterite particles for the micromanipulation of single biological molecules such as DNA or specific proteins in an optical trap capable of exerting and measuring torques. The stabilized birefringent microspheres may also find use for biosensor and biological screening applications.
Publisher: IOP Publishing
Date: 24-07-2007
Publisher: SPIE
Date: 12-09-2013
DOI: 10.1117/12.2024254
Publisher: Elsevier BV
Date: 06-2003
Publisher: American Physical Society (APS)
Date: 09-10-2006
Publisher: IOP Publishing
Date: 26-09-2008
Publisher: Optica Publishing Group
Date: 2007
DOI: 10.1364/OE.15.005521
Abstract: We integrate the optical elements required to generate optical orbital angular momentum into a microdevice. This allows the rotation of either naturally occuring microparticles or specially fabricated optical rotors. We use a two photon photopolymerization process to create microscopic diffractive optical elements, customized to a wavelength of choice, which are integrated with micromachines in microfluidic devices. This enables the application of high optical torques with off-the-shelf optical tweezers systems.
Publisher: SPIE
Date: 31-01-2012
DOI: 10.1117/12.923136
Publisher: Informa UK Limited
Date: 03-2001
Publisher: SPIE
Date: 19-08-2010
DOI: 10.1117/12.861880
Publisher: Elsevier BV
Date: 09-1995
Publisher: Springer Science and Business Media LLC
Date: 31-08-2015
Publisher: Springer Science and Business Media LLC
Date: 23-07-1998
DOI: 10.1038/28566
Publisher: Wiley
Date: 05-2008
DOI: 10.1111/J.1751-1097.2007.00273.X
Abstract: We have synthesized a compound ideally suited to the study of structure-function relationships in eumelanin synthesis. N-methyl-5-hydroxy-6-methoxy-indole (MHMI) has key functional groups strategically placed on the indole framework to hinder binding in the 2, 5, 6 and 7 positions. Thus, the dimer bound exclusively in the 4-4' positions was isolated and characterized. In order to study the difference in vibrational structure between the MHMI monomer and dimer, Raman spectra were acquired of both compounds, as well as indole, indole-2-carboxylic acid and 5,6-dihydroxyindole-2-carboxylic acid (DHICA). Peaks were assigned to particular vibrational modes using B3LYP density functional theory calculations, and experimental and theoretical spectra displayed good agreement. Addition of functional groups to either benzene or pyrrole rings in the indole framework impacted vibrational spectra attributed to vibrations in either ring, and in some cases, peaks appearing unchanged between two compounds corresponded to different contributing vibrations. Dimerization resulted in an expected increase in the number of vibrational modes, but not a significant increase in the number of apparent peaks, as several modes frequently contributed to an in idual observed peak. Comparison of spectral features of the monomer and dimer provides insight into eumelanin photochemistry, but final conclusions depend on the planarity of oligomeric structure in vivo.
Publisher: Optica Publishing Group
Date: 12-2004
DOI: 10.1364/OL.29.002704
Abstract: We present a new method of laser frequency locking in which the feedback signal is directly proportional to the detuning from an atomic transition, even at detunings many times the natural linewidth of the transition. Our method is a form of sub-Doppler polarization spectroscopy, based on measuring two Stokes parameters (I2 and I3) of light transmitted through a vapor cell. It extends the linear capture range of the lock loop by as much as an order of magnitude and provides frequency discrimination equivalent to or better than those of other commonly used locking techniques.
Publisher: Elsevier
Date: 2008
Publisher: Elsevier BV
Date: 02-2007
DOI: 10.1016/J.MICRON.2006.07.010
Abstract: Theory describing a super-resolution microscopy experiment using temporally and spatially coherent structured illumination was developed, and used to derive a method for processing experimental data. Numerical simulations were performed to verify that the method can, in principle, produce super-resolved images that are exactly equivalent to an image processed by a system with a much larger aperture (that is, the correct weighting between different regions of the image spectrum is maintained). The process was then demonstrated experimentally, showing a factor of two improvement in resolution over a diffraction-limited, coherently illuminated, microscope.
Publisher: Public Library of Science (PLoS)
Date: 29-01-2014
Publisher: Springer Science and Business Media LLC
Date: 20-09-2017
DOI: 10.1038/S41467-017-00713-2
Abstract: The vestibular system, which detects gravity and motion, is crucial to survival, but the neural circuits processing vestibular information remain incompletely characterised. In part, this is because the movement needed to stimulate the vestibular system h ers traditional neuroscientific methods. Optical trapping uses focussed light to apply forces to targeted objects, typically ranging from nanometres to a few microns across. In principle, optical trapping of the otoliths (ear stones) could produce fictive vestibular stimuli in a stationary animal. Here we use optical trapping in vivo to manipulate 55-micron otoliths in larval zebrafish. Medial and lateral forces on the otoliths result in complementary corrective tail movements, and lateral forces on either otolith are sufficient to cause a rolling correction in both eyes. This confirms that optical trapping is sufficiently powerful and precise to move large objects in vivo, and sets the stage for the functional mapping of the resulting vestibular processing.
Publisher: American Physical Society (APS)
Date: 15-10-2010
Publisher: IOP Publishing
Date: 13-06-2013
Publisher: SPIE
Date: 28-08-2008
DOI: 10.1117/12.798529
Publisher: Optica Publishing Group
Date: 1998
DOI: 10.1364/OL.23.000001
Abstract: We show theoretically and demonstrate experimentally that highly absorbing particles can be trapped and manipulated in a single highly focused Gaussian beam. Our studies of the effects of polarized light on such particles show that they can be set into rotation by elliptically polarized light and that both the sense and the speed of their rotation can be smoothly controlled.
Publisher: American Association for the Advancement of Science (AAAS)
Date: 28-06-2019
Abstract: Many-body systems generally become more disordered as more energy is pumped into them. A curious exception to this rule was predicted in the context of turbulent flow by the physical chemist Lars Onsager. He suggested that the entropy of certain two-dimensional (2D) systems can decrease with increasing energy, corresponding to an effective negative temperature. Using 2D Bose-Einstein condensates of atoms, Gauthier et al. and Johnstone et al. put Onsager's theory to the test. They provided energy to the system by perturbing the condensate, creating vortices and antivortices. With increasing energy, the system became more ordered as clusters containing either only vortices or only antivortices emerged. Science , this issue p. 1264 , p. 1267
Publisher: SPIE
Date: 09-10-2012
DOI: 10.1117/12.929365
Publisher: American Physical Society (APS)
Date: 10-02-2009
Publisher: American Physical Society (APS)
Date: 19-09-2007
Publisher: Optica Publishing Group
Date: 10-12-2004
DOI: 10.1364/AO.43.006384
Abstract: Near-resonant holographic interferometry is demonstrated to measure temperature and species concentration in a two-dimensional steady premixed air-acetylene flame. A peak temperature of (2600 +/- 100) K and a peak OH number density of (9.6 +/- 0.3) x 10(22) m(-3) are obtained, consistent with the expected values for such a flame. These values are determined by recording interferograms with a laser assumed sufficiently detuned from line center so that pressure and temperature broadening can be ignored. The results are thus obtained without making prior assumptions on the temperature or pressure of the flame beyond the existence of thermal equilibrium.
Publisher: IOP Publishing
Date: 15-08-2014
Publisher: Optica Publishing Group
Date: 2006
DOI: 10.1364/OE.14.006963
Abstract: We describe a way to determine the total angular momentum, both spin and orbital, transferred to a particle trapped in optical tweezers. As an ex le an LG(02) mode of a laser beam with varying degrees of circular polarisation is used to trap and rotate an elongated particle with a well defined geometry. The method successfully estimates the total optical torque applied to the particle. For this technique, there is no need to measure the viscous drag on the particle, as it is an optical measurement. Therefore, knowledge of the particle's size and shape, as well as the fluid's viscosity, is not required.
Publisher: SPIE
Date: 31-08-2006
DOI: 10.1117/12.681402
Publisher: American Physical Society (APS)
Date: 31-01-2011
Publisher: Wiley
Date: 02-06-2014
Abstract: A cavity optomechanical magneto-meter operating in the 100 pT range is reported. The device operates at earth field, achieves tens of megahertz bandwidth with 60 μm spatial resolution and microwatt optical-power requirements. These unique capabilities may have a broad range of applications including cryogen-free and microfluidic magnetic resonance imaging (MRI), and investigation of spin-physics in condensed matter systems.
Publisher: Springer Science and Business Media LLC
Date: 31-10-2014
DOI: 10.1038/SREP06866
Publisher: Springer Science and Business Media LLC
Date: 30-11-2020
DOI: 10.1038/S41467-020-19982-5
Abstract: Hearing is a crucial sense in underwater environments for communication, hunting, attracting mates, and detecting predators. However, the tools currently used to study hearing are limited, as they cannot controllably stimulate specific parts of the auditory system. To date, the contributions of hearing organs have been identified through lesion experiments that inactivate an organ, making it difficult to gauge the specific stimuli to which each organ is sensitive, or the ways in which inputs from multiple organs are combined during perception. Here, we introduce Bio-Opto-Acoustic (BOA) stimulation, using optical forces to generate localized vibrations in vivo, and demonstrate stimulation of the auditory system of zebrafish larvae with precise control. We use a rapidly oscillated optical trap to generate vibrations in in idual otolith organs that are perceived as sound, while adjacent otoliths are either left unstimulated or similarly stimulated with a second optical laser trap. The resulting brain-wide neural activity is characterized using fluorescent calcium indicators, thus linking each otolith organ to its in idual neuronal network in a way that would be impossible using traditional sound delivery methods. The results reveal integration and cooperation of the utricular and saccular otoliths, which were previously described as having separate biological functions, during hearing.
Publisher: American Physical Society (APS)
Date: 29-07-2013
Publisher: American Vacuum Society
Date: 25-08-2021
DOI: 10.1116/5.0026178
Abstract: Atomtronics deals with matter-wave circuits of ultracold atoms manipulated through magnetic or laser-generated guides with different shapes and intensities. In this way, new types of quantum networks can be constructed in which coherent fluids are controlled with the know-how developed in the atomic and molecular physics community. In particular, quantum devices with enhanced precision, control, and flexibility of their operating conditions can be accessed. Concomitantly, new quantum simulators and emulators harnessing on the coherent current flows can also be developed. Here, the authors survey the landscape of atomtronics-enabled quantum technology and draw a roadmap for the field in the near future. The authors review some of the latest progress achieved in matter-wave circuits' design and atom-chips. Atomtronic networks are deployed as promising platforms for probing many-body physics with a new angle and a new twist. The latter can be done at the level of both equilibrium and nonequilibrium situations. Numerous relevant problems in mesoscopic physics, such as persistent currents and quantum transport in circuits of fermionic or bosonic atoms, are studied through a new lens. The authors summarize some of the atomtronics quantum devices and sensors. Finally, the authors discuss alkali-earth and Rydberg atoms as potential platforms for the realization of atomtronic circuits with special features.
Publisher: IOP Publishing
Date: 20-01-2009
Publisher: Springer Science and Business Media LLC
Date: 07-2000
Publisher: AIP Publishing
Date: 08-2014
DOI: 10.1063/1.4892375
Abstract: We describe a magnetic coil design utilizing concentrically wound electro-magnetic insulating (EMI) foil (25.4 μm Kapton backing and 127 μm thick layers). The magnetic coils are easily configurable for different coil sizes, while providing large surfaces for low-pressure (0.12 bar) water cooling. The coils have turn densities of ∼5 mm−1 and achieve a maximum of 377 G at 2.1 kW driving power, measured at a distance 37.9 mm from the axial center of the coil. The coils achieve a steady-state temperature increase of 36.7°C/kW.
Publisher: Springer Science and Business Media LLC
Date: 28-02-2007
Publisher: American Physical Society (APS)
Date: 27-02-2009
Publisher: American Physical Society (APS)
Date: 26-08-2004
Publisher: Wiley
Date: 06-06-2003
Abstract: Optically transparent, mesostructured titanium dioxide thin films were fabricated using an hiphilic poly(alkylene oxide) block copolymer template in combination with retarded hydrolysis of a titanium isopropoxide precursor. Prior to calcination, the films displayed a stable hexagonal mesophase and high refractive indices (1.5 to 1.6) relative to mesostructured silica (1.43). After calcination, the hexagonal mesophase was retained with surface areas > 300 m2 g-1. The dye Rhodamine 6G (commonly used as a laser dye) was incorporated into the copolymer micelle during the templating process. In this way, novel dye-doped mesostructured titanium dioxide films were synthesised. The copolymer not only directs the film structure, but also provides a solubilizing environment suitable for sustaining a high monomer-to-aggregate ratio at elevated dye concentrations. The dye-doped films displayed optical thresholdlike behaviour characteristic of lified spontaneous emission. Soft lithography was successfully applied to micropattern the dye-doped films. These results pave the way for the fabrication and demonstration of novel microlaser structures and other active optical structures. This new, high-refractive index, mesostructured, dye-doped material could also find applications in areas such as optical coatings, displays and integrated photonic devices.
Publisher: Elsevier BV
Date: 07-2007
Publisher: SPIE
Date: 13-09-2007
DOI: 10.1117/12.735341
Publisher: SPIE
Date: 08-09-2011
DOI: 10.1117/12.894969
Publisher: Elsevier BV
Date: 10-2006
Publisher: American Physical Society (APS)
Date: 31-03-2009
Publisher: IOP Publishing
Date: 04-2023
Abstract: Optical tweezers are tools made of light that enable contactless pushing, trapping, and manipulation of objects, ranging from atoms to space light sails. Since the pioneering work by Arthur Ashkin in the 1970s, optical tweezers have evolved into sophisticated instruments and have been employed in a broad range of applications in the life sciences, physics, and engineering. These include accurate force and torque measurement at the femtonewton level, microrheology of complex fluids, single micro- and nano-particle spectroscopy, single-cell analysis, and statistical-physics experiments. This roadmap provides insights into current investigations involving optical forces and optical tweezers from their theoretical foundations to designs and setups. It also offers perspectives for applications to a wide range of research fields, from biophysics to space exploration.
Publisher: IOP Publishing
Date: 24-06-2013
Publisher: Springer Science and Business Media LLC
Date: 10-1998
DOI: 10.1038/27014
Publisher: SPIE
Date: 18-10-2004
DOI: 10.1117/12.557090
Publisher: Optica Publishing Group
Date: 09-09-2008
DOI: 10.1364/OE.16.015039
Abstract: We calculate trapping forces, trap stiffness and interference effects for spherical particles in optical tweezers using electromagnetic theory. We show the dependence of these on relative refractive index and particle size. We investigate resonance effects, especially in high refractive index particles where interference effects are expected to be strongest. We also show how these simulations can be used to assist in the optimal design of traps.
Publisher: American Chemical Society (ACS)
Date: 17-03-2009
DOI: 10.1021/JP900887R
Publisher: Informa UK Limited
Date: 12-1991
Publisher: SPIE
Date: 13-09-2007
DOI: 10.1117/12.735492
Publisher: Elsevier
Date: 2008
Publisher: American Institute of Aeronautics and Astronautics (AIAA)
Date: 11-2003
DOI: 10.2514/2.6833
Publisher: SPIE
Date: 28-08-2008
DOI: 10.1117/12.794385
Publisher: SPIE
Date: 31-08-2006
DOI: 10.1117/12.680455
Publisher: SPIE
Date: 28-08-2008
DOI: 10.1117/12.793577
Publisher: Elsevier BV
Date: 08-2001
Publisher: American Physical Society (APS)
Date: 10-2007
Publisher: Royal Society of Chemistry (RSC)
Date: 2018
DOI: 10.1039/C7LC01176H
Abstract: The characterisation of physical properties in biologically relevant processes and the development of novel microfluidic devices for this purpose are experiencing a great resurgence at present.
Publisher: SPIE
Date: 19-08-2010
DOI: 10.1117/12.861793
Publisher: SPIE
Date: 14-03-2005
DOI: 10.1117/12.591220
Publisher: IOP Publishing
Date: 08-10-2020
Abstract: Since their invention in the 1980s, optical tweezers have found a wide range of applications, from biophotonics and mechanobiology to microscopy and optomechanics. Simulations of the motion of microscopic particles held by optical tweezers are often required to explore complex phenomena and to interpret experimental data. For the sake of computational efficiency, these simulations usually model the optical tweezers as an harmonic potential. However, more physically-accurate optical-scattering models are required to accurately model more onerous systems this is especially true for optical traps generated with complex fields. Although accurate, these models tend to be prohibitively slow for problems with more than one or two degrees of freedom (DoF), which has limited their broad adoption. Here, we demonstrate that machine learning permits one to combine the speed of the harmonic model with the accuracy of optical-scattering models. Specifically, we show that a neural network can be trained to rapidly and accurately predict the optical forces acting on a microscopic particle. We demonstrate the utility of this approach on two phenomena that are prohibitively slow to accurately simulate otherwise: the escape dynamics of swelling microparticles in an optical trap, and the rotation rates of particles in a superposition of beams with opposite orbital angular momenta. Thanks to its high speed and accuracy, this method can greatly enhance the range of phenomena that can be efficiently simulated and studied.
Publisher: American Physical Society (APS)
Date: 12-06-2006
Publisher: SPIE
Date: 09-10-2012
DOI: 10.1117/12.930411
Publisher: SPIE
Date: 09-10-2012
DOI: 10.1117/12.930137
Publisher: Informa UK Limited
Date: 07-2006
Publisher: Royal Society of Chemistry (RSC)
Date: 2006
DOI: 10.1039/B608669A
Abstract: We present a method for characterizing microscopic optical force fields. Two dimensional vector force maps are generated by measuring the optical force applied to a probe particle for a grid of particle positions. The method is used to map out the force field created by the beam from a lensed fiber inside a liquid filled microdevice. We find transverse gradient forces and axial scattering forces on the order of 2 pN per 10 mW laser power which are constant over a considerable axial range (>35 microm). These findings suggest future useful applications of lensed fibers for particle guiding/sorting. The propulsion of a small particle at a constant velocity of 200 microm s(-1) is shown.
Publisher: The Optical Society
Date: 11-03-2015
DOI: 10.1364/OE.23.007190
Publisher: American Institute of Aeronautics and Astronautics (AIAA)
Date: 09-2000
DOI: 10.2514/2.1154
Publisher: AIP Publishing
Date: 05-2008
DOI: 10.1063/1.2919574
Abstract: An antireflection coating improves the trapping of high-index particles in optical tweezers by reducing the scattering force. This can allow the strong trapping of high-index particles that cannot normally be trapped, and the use of lower numerical aperture objectives while still obtaining strong trapping. The improvement is not overly sensitive to the refractive index or thickness of the coating.
Publisher: IOP Publishing
Date: 15-09-2009
Publisher: American Physical Society (APS)
Date: 12-10-2009
Publisher: American Physical Society (APS)
Date: 05-12-2011
Publisher: Elsevier
Date: 2007
Publisher: IOP Publishing
Date: 09-07-2004
Publisher: American Physical Society (APS)
Date: 27-12-2019
Publisher: American Physical Society (APS)
Date: 17-01-2007
Publisher: SPIE
Date: 14-03-2005
DOI: 10.1117/12.590147
Publisher: IOP Publishing
Date: 04-03-2011
Publisher: Optica Publishing Group
Date: 19-11-0019
DOI: 10.1364/AO.43.003391
Abstract: The development of near-resonant holographic interferometry techniques for use on flows seeded with atomic species is described. A theoretical model for the refractivity that is due to the seed species is outlined, and an approximation to this model is also described that is shown to be valid for practical regimes of interest and allows the number density of the species to be determined without knowledge of line-broadening effects. The details of quantitative number density experiments performed on an air-acetylene flame are given, and a comparison with an alternative absorption-based experiment is made.
No related organisations have been discovered for Halina Rubinsztein-Dunlop.
Start Date: 2005
End Date: 2005
Funder: Australian Research Council
View Funded ActivityStart Date: 2016
End Date: 2018
Funder: Australian Research Council
View Funded ActivityStart Date: 2004
End Date: 2009
Funder: Australian Research Council
View Funded ActivityStart Date: 2003
End Date: 2003
Funder: Australian Research Council
View Funded ActivityStart Date: 2003
End Date: 2003
Funder: Australian Research Council
View Funded Activity