Optical ferris wheel for ultracold atoms

Author(s): S. Franke-Arnold, J. Leach, M. J. Padgett, V. E. Lembessis, D. Ellinas, A. J. Wright, J. M. Girkin, P. Ohberg, and A. S. Arnold

Abstract:

“We propose a versatile optical ring lattice suitable for trapping cold and quantum degenerate atomic samples. We demonstrate the realisation of intensity patterns from pairs of Laguerre-Gauss (exp(iℓө) modes with different ℓ indices. These patterns can be rotated by introducing a frequency shift between the modes. We can generate bright ring lattices for trapping atoms in red-detuned light, and dark ring lattices suitable for trapping atoms with minimal heating in the optical vortices of blue-detuned light. The lattice sites can be joined to form a uniform ring trap, making it ideal for studying persistent currents and the Mott insulator transition in a ring geometry. ”

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Publication: Optics Express
Issue/Year: Optics Express, Vol. 15, Issue 14, pp. 8619-8625 (2007)
DOI: 10.1364/OE.15.008619

Dynamic speckle illumination microscopy with wavelet prefiltering

Author(s): Cathie Ventalon, Rainer Heintzmann, and Jerome Mertz

Abstract:

“Dynamic speckle illumination (DSI) provides a simple and robust technique to obtain fluorescence depth sectioning with a widefield microscope. We report a significant improvement to DSI microscopy based on a statistical image-processing algorithm that incorporates spatial wavelet prefiltering. The resultant gain in sectioning strength leads to a fundamentally improved scaling law for the out-of-focus background rejection.”

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Publication: Optics Letters
Issue/Year: Optics Letters, Vol. 32, Issue 11, pp. 1417-1419
DOI: 10.1364/OL.32.001417

Holographic and single beam optical manipulation of hyphal growth in filamentous fungi

Author(s): D. R. Burnham, G. D. Wright, N. D. Read and D. McGloin

Abstract:

“We report on the ability of holographic light fields to alter the normal growth patterns of filamentous fungi. The light fields are produced on a microscopic scale by borrowing methods from the field of optical tweezers, but without the aim of directly trapping or manipulating objects. Extended light fields are shown to redirect and constrict hyphal tip growth, and induce hyphal branching in a highly reproducible manner. The merits of using discrete and continuous light fields produced using a spatial light modulator are discussed and the use of three-dimensional ‘pseudowalls’ of light to control the growth patterns is reported. We also demonstrate the dependence of hyphal tip growth on the wavelength of light, finding that less power is needed at shorter wavelengths to effect changes in the growth dynamics of fungal hyphae.”

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Publication: Journal of Optics A: Pure and Applied Optics
Issue/Year: J. Opt. A: Pure Appl. Opt. 9 S172-S179 (2007)
DOI: 10.1088/1464-4258/9/8/S09

Holografisch generierte Doppelfallen für dreidimensionales Trapping

Author(s): Susanne Zwick, L. He, M. Warber, T. Haist, W. Osten

Abstract:

“In konventionellen optischen Pinzetten ist der axiale Einfang von mikroskopischen Partikeln nur durch starke Fokussierung des Laserstrahls mit einem hochaperturigen Mikroskopobjektiv möglich. Wir stellen ein Verfahren vor, mit dem der axiale Einfang in holografischen Pinzetten auch mit niederaperturigen Objektiven ermöglicht wird.”

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Publication: DGaO Proceedings
ISSN: 1614-8436

Computer generation of optimal holograms for optical trap arrays

Author(s): Roberto Di Leonardo, Francesca Ianni, and Giancarlo Ruocco

Abstract:

“We propose a new iterative algorithm for obtaining optimal holograms targeted to the generation of arbitrary three dimensional structures of optical traps. The algorithm basic idea and performance are discussed in conjunction to other available algorithms. We show that all algorithms lead to a phase distribution maximizing a specific performance quantifier, expressed as a function of the trap intensities. In this scheme we go a step further by introducing a new quantifier and the associated algorithm leading to unprecedented efficiency and uniformity in trap light distributions. The algorithms performances are investigated both numerically and experimentally.”

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Publication: Optics Express
Issue/Year: Optics Express, Vol. 15, Issue 4, pp. 1913-1922
DOI: 10.1364/OE.15.001913

Optically controlled grippers for manipulating micron-sized particles

Author(s): Graham Gibson, Louise Barron, Fiona Beck, Graeme Whyte and Miles Padgett

Abstract:

“We report the development of a joystick controlled gripper for the real-time manipulation of micron-sized objects, driven using holographic optical tweezers (HOTs). The gripper consists of an arrangement of four silica beads, located in optical traps, which can be positioned and scaled in order to trap an object indirectly. The joystick can be used to grasp, move (lateral or axial), and change the orientation of the target object. The ability to trap objects indirectly allows us to demonstrate the manipulation of a strongly scattering micron-sized metallic particle.”

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Publication:New Journal of Physics
Issue/Year: New J. Phys. 9 14, Jan. 2007
DOI: 10.1088/1367-2630/9/1/014

Automated trapping, assembly, and sorting with holographic optical tweezers

Author(s): Stephen C. Chapin, Vincent Germain, and Eric R. Dufresne

Abstract:

“We combine real-time feature recognition with holographic optical tweezers to automatically trap, assemble, and sort micron-sized colloidal particles. Closed loop control will enable new applications of optical micromanipulation in biology, medicine, materials science, and possibly quantum computation.”

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Publication: Optics Express
Issue/Year: Optics Express, Vol. 14, Issue 26, pp. 13095-13100 , 2006
DOI: 10.1364/OE.14.013095

Reverse orbiting of microparticles in optical vortices

Author(s): A. Jesacher, S. Fürhapter, C. Maurer, S. Bernet, and M. Ritsch-Marte

Abstract:

“We report the observation of particles trapped at an air-water surface orbiting in a reverse direction with respect to the orbital angular momentum of the light field. The effect is explained by a combination of asymmetric particle shape and confinement of the particle on the 2D air-water interface. The experiment highlights the strong influence of the particle shape on the momentum transfer, an effect that is often not considered in optical trapping experiments.”

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Publication: Optics Letters
Issue/Year: Optics Letters, Vol. 31, Issue 19, pp. 2824-2826
DOI: 10.1364/OL.31.002824

Algorithm for computing holographic optical tweezers at video rates

Author(s): Mario Montes-Usategui, Encarnación Pleguezuelos, Jordi Andilla, Estela Martín-Badosa, and Ignacio Juvells

Abstract:

“Digital holography enables the creation of multiple optical traps at arbitrary three-dimensional locations and spatial light modulators permit updating those holograms at video rates. However, the time required for computing the holograms makes interactive optical manipulation of several samples difficult to achieve. We introduce an algorithm for computing holographic optical tweezers that is both easy to implement and capable of speeds in excess of 10 Hz when running on a Pentium IV computer. A discussion of the pros and cons of the algorithm, a mathematical analysis of the efficiency of the resulting traps, as well as results of the three-dimensional manipulation of polystyrene micro spheres are included.”

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Publication: SPIE Digital Library
Issue/Year: Proceedings Volume 6326, Optical Trapping and Optical Micromanipulation III; 63262X (2006)
DOI: 10.1117/12.680504

Design of a low-cost interactive holographic optical tweezers system

Author(s): E. Pleguezuelos, J. Andilla, A. Carnicer, E. Martín-Badosa, S. Vallmitjana, and M. Montes-Usategui.

Abstract:

“The paper describes the design of an inexpensive holographic optical tweezers setup. The setup is accompanied by software that allows real-time manipulation of the sample and takes into account the experimental features of the setup, such as aberration correction and LCD modulation. The LCD, a HoloEye LCR-2500, is the physical support of the holograms, which are calculated using the fast random binary mask algorithm. The real-time software achieves 12 fps at full LCD resolution (including aberration correction and modulation) when run on a Pentium IV HT, 3.2 GHz computer.”

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Publication: SPIE Proceedings
Issue/Year: Proc. SPIE 6326, 63262Q (2006)
DOI: 10.1117/12.680593