Optical Tweezers

Jones, Philip H.; Maragó, Onofrio M.; Volpe, Giovanni

doi:10.1017/cbo9781107279711

Cited by 336 publications

(224 citation statements)

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“…The laser power at each trapping site is kept low enough (≃2 mW) to avoid significant heating ( (ref. 40 )). The DVM uses a monochromatic camera acquiring videos at 200 fps; these frames are analysed using standard DVM algorithms to determine the projected positions of the particles with nanometric accuracy 35 36 (see Methods for details).…”

Section: Resultsmentioning

confidence: 99%

“…where r i is the position of the centre of particle i , Δ r i = r i − R i , and R i is the position of the centre of the i th trap, while d ij =| r i − r j |−2 R is the distance between the surfaces of particles i and j . The optical traps are harmonic 40 , that is,…”

Section: Resultsmentioning

confidence: 99%

“…We have therefore developed an experimental set-up capable of manipulating and observing multiple particles in the bulk of a critical mixture. Our set-up is based on a combination of HOTs 34 40 and DVM 35 36 40 ; its schematic is shown in Supplementary Fig. 1 .…”

Section: Resultsmentioning

confidence: 99%

“…2 ). The six traps are sufficiently far apart to guarantee the independence of the optical potentials 40 . The internal traps are used to hold either two ( Fig.…”

Section: Resultsmentioning

confidence: 99%

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Nonadditivity of critical Casimir forces

et al. 2016

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In soft condensed matter physics, effective interactions often emerge due to the spatial confinement of fluctuating fields. For instance, microscopic particles dissolved in a binary liquid mixture are subject to critical Casimir forces whenever their surfaces confine the thermal fluctuations of the order parameter of the solvent close to its critical demixing point. These forces are theoretically predicted to be nonadditive on the scale set by the bulk correlation length of the fluctuations. Here we provide direct experimental evidence of this fact by reporting the measurement of the associated many-body forces. We consider three colloidal particles in optical traps and observe that the critical Casimir force exerted on one of them by the other two differs from the sum of the forces they exert separately. This three-body effect depends sensitively on the distance from the critical point and on the chemical functionalisation of the colloid surfaces.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

“…2 ). The six traps are sufficiently far apart to guarantee the independence of the optical potentials 40 . The internal traps are used to hold either two ( Fig.…”

Section: Resultsmentioning

confidence: 99%

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Nonadditivity of critical Casimir forces

et al. 2016

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“…The image displayed on the screen corresponds to the amplitude or phase pattern displayed on the device. There are numerous guides for setting up one of these devices in an optical tweezers system [13,14], and many of these guides describe generating SLM patterns for beam shaping but they do not provide easy to use codes.…”

Section: Device Overview and Operationmentioning

confidence: 99%

OTSLM toolbox for Structured Light Methods

Lenton

Stilgoe

Nieminen

et al. 2020

Computer Physics Communications

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We present a new Matlab toolbox for generating phase and amplitude patterns for digital micro-mirror device (DMD) and liquid crystal (LC) based spatial light modulators (SLMs). This toolbox consists of a collection of algorithms commonly used for generating patterns for these devices with a focus on optical tweezers beam shaping applications. In addition to the algorithms provided, we have put together a range of user interfaces for simplifying the use of these patterns. The toolbox currently has functionality to generate patterns which can be saved as a image or displayed on a device/screen using the supplied interface. We have only implemented interfaces for the devices our group currently uses but we believe that extending the code we provide to other devices should be fairly straightforward. The range of algorithms included in the toolbox is not exhaustive. However, by making the toolbox open sources and available on GitHub we hope that other researchers working with these devices will contribute their patterns/algorithms to the toolbox. There are many algorithms for generating computer controlled holograms however the code and descriptions for these algorithms is often provided as supplementary material to research publications which use these methods, and in some cases only the description is provided without code to reproduce the pattern. Furthermore, implementation of these algorithms can be a time consuming task. Even for simple patterns with simple analytical expressions for the far-field phase or amplitude, such as the Laguerre-Gaussian and Hermite-Gaussian beams, time is often wasted by researchers having to re-implement and test these patterns. Existing libraries for generation of SLM patterns focus on specific tasks, methods of pattern generation, or target specific hardware. These libraries are not general purpose or easily modifiable for general use by researchers working with computer controlled holograms in fields such as beam shaping and optical tweezers. Solution method:We have assembled a toolbox containing many methods commonly used with these devices. The number of methods available makes assembling a complete toolbox impossible, instead we have focused on putting together a general collection of methods, in the form of an open source toolbox, with the hope that other researchers will contribute patterns/algorithms they use. The toolbox currently includes a range of simple and iterative methods for beam shaping and steering as well as some of the methods our group currently uses for SLM control, calibration, imaging and optical tweezers beam shaping. To make the tools we have developed easy to use, we have tried to maintain a consistent well documented interface to each of the functions and provided graphical user interfaces to many of the simpler functions enabling code-free pattern generation. Additional comments: Some of the features require the Optical Tweezers Toolbox [1], in particular, the non-paraxial beam visualisation and optimisation routines. Certain functions require components...

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