Dynamic optical manipulation using intensity patterns directly projected by a reflective spatial light modulator

Author(s): S. H. Tao, X.-C. Yuan, H. B. Niu and X. Peng

Abstract:

“We propose a simple method to manipulate microparticles dynamically with intensity-modulated patterns projected by a spatial light modulator (SLM), on which the patterns are controlled by a computer directly. The patterns are intensity–intensity modulated by the SLM without involving any computation or algorithm. With the dynamic patterns we can manipulate particles interactively and visibly by drawing or mouse-dragging pictures or even playing a video file on the computer screen. Experimental observations verified the feasibility of the proposed technique as a simple and direct solution for interactive optical manipulation.”

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Publication: Review of Scientific Instruments
Issue/Year: Rev. Sci. Instrum. 76, 056103 (2005)
DOI: 10.1063/1.1898065

Structure and scaling of helical modes of light

Author(s): Steven Sundbeck, Ilya Gruzberg, and David G. Grier

Abstract:

“Modes of light that contain topological defects such as screw dislocations can be focused into optical traps with interesting and useful properties. The way in which the intensity distribution within helical modes of light varies with topological charge is discussed, and new scaling predictions for their radial profiles that are consistent with experimental observations are introduced.”

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Publication: Optics Letters
Issue/Year: Optics Letters, Vol. 30, Issue 5, pp. 477-479 , 2005
DOI: 10.1364/OL.30.000477

Spiral phase contrast imaging in microscopy

Author(s): Severin Fürhapter, Alexander Jesacher, Stefan Bernet, and Monika Ritsch-Marte

Abstract:

“We demonstrate an optical method for edge contrast enhancement in light microscopy. The method is based on holographic Fourier plane filtering of the microscopic image with a spiral phase element (also called vortex phase or helical phase filter) displayed as an off-axis hologram at a computer controlled high resolution spatial light modulator (SLM) in the optical imaging pathway. The phase hologram imprints a helical phase term of the form exp(i ??) on the diffracted light field in its Fourier plane. In the image plane, this results in a strong and isotropic edge contrast enhancement for both amplitude and phase objects.”

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Publication: Optics Express
Issue/Year: Optics Express, Vol. 13, Issue 3, pp. 689-694, 2005
DOI: 10.1364/OPEX.13.000689

Photoporation and cell transfection using a violet diode laser

Author(s): L. Paterson, B. Agate, M. Comrie, R. Ferguson, T. Lake, J. Morris, A. Carruthers, C. T. Brown, W. Sibbett, P. Bryant, F. Gunn-Moore, A. Riches, and Kishan Dholakia

Abstract:

“The introduction and subsequent expression of foreign DNA inside living mammalian cells (transfection) is achieved by photoporation with a violet diode laser. We direct a compact 405 nm laser diode source into an inverted optical microscope configuration and expose cells to 0.3 mW for 40 ms. The localized optical power density of ~1200 MW/m2 is six orders of magnitude lower than that used in femtosecond photoporation (~104 TW/m2). The beam perforates the cell plasma membrane to allow uptake of plasmid DNA containing an antibiotic resistant gene as well as the green fluorescent protein (GFP) gene. Successfully transfected cells then expand into clonal groups which are used to create stable cell lines. The use of the violet diode laser offers a new and simple poration technique compatible with standard microscopes and is the simplest method of laser-assisted cell poration reported to date.”

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Publication: Optics Express
Issue/Year: Optics Express, Vol. 13, Issue 2, pp. 595-600, 2005
DOI: 10.1364/OPEX.13.000595

Assembly of 3-dimensional structures using programmable holographic optical tweezers

Author(s): Gavin Sinclair, Pamela Jordan, Johannes Courtial, Miles Padgett, Jon Cooper, and Zsolt Laczik

Abstract:

“The micromanipulation of objects into 3-dimensional geometries within holographic optical tweezers is carried out using modified Gerchberg-Saxton (GS) and direct binary search (DBS) algorithms to produce the hologram designs. The algorithms calculate sequences of phase holograms, which are implemented using a spatial light modulator, to reconfigure the geometries of optical traps in many planes simultaneously. The GS algorithm is able to calculate holograms quickly from the initial, intermediate and final trap positions. In contrast, the DBS algorithm is slower and therefore used to pre-calculate the holograms, which are then displayed in sequence. Assembly of objects in a variety of 3-D configurations is semi-automated, once the traps in their initial positions are loaded.”

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Publication: Optics Express
Issue/Year: Optics Express, Vol. 12, Issue 22, pp. 5475-5480, 2004
DOI: 10.1364/OPEX.12.005475

Size selective trapping with optical ”cogwheel” tweezers

Author(s): Alexander Jesacher, Severin Fürhapter, Stefan Bernet, and Monika Ritsch-Marte

Abstract:

“We experimentally investigate the size-selective trapping behavior of Laguerre-Gaussian beams (”doughnut-beams”) and ”cogwheel”-shaped beams which are collinear superpositions of two doughnut beams of equal opposite helical index. Experimentally they are created by diffraction of a Gaussian laser beam at a high resolution refractive spatial light modulator (SLM). In the focus of an optical microscope such a beam looks similar to a ”cogwheel”, i.e. the light intensity is periodically modulated around the circumference of a sphere with a precisely adjustable diameter. In an optical tweezers setup these modes can be used to trap particles or cells, provided their sizes exceed the ring diameter by a fixed amount. This promises a convenient method of constructing an optical tweezers system in microscopy which acts as a passive sorter for particles of differing sizes.”

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Publication: Optics Express
Issue/Year: Optics Express, Vol. 12, Issue 17, pp. 4129-4135, 2004
DOI: 10.1364/OPEX.12.004129

Multiple Optical Trapping by Means of Diffractive Optical Elements

Author(s): Dan Cojoc, Valentina Emiliani, Enrico Ferrari, Radu Malureanu, Stefano Cabrini, Remo Zaccaria Proiettiand Enzo Di Fabrizio

Abstract:

“In this paper we report multiple optical trapping of microscopic dielectric particles using diffractive optical elements implemented on twisted nematic liquid crystal spatial light modulators. The particles are trapped in arrays disposed in plane or in volume and can be moved independently in x-y-z by changing the configuration of the diffractive optical element. We show also multiple trapping using Laguerre-Gaussian and Gaussian beams simultaneously. The orbital angular momentum of the Laguerre-Gaussian beam is transferred to the particle, making it to move on a circular trajectory defined by the intensity pattern specific to this beam. We use sample cells built with two microscope slides separated by 120 µm with a sticky tape. The space between the two slides is filled with 2 µm diameter silica spheres diluted in water (concentration 0.026% wt). We show that optical trapping is also possible in a small glass capillary with a diameter of 100 µm. ”

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Publication: Japanese Journal of Applied Physics
Issue/Year: Jpn. J. Appl. Phys. 43 (2004) pp. 3910-3915
DOI: 10.1143/JJAP.43.3910

Diffractive optical tweezers in the Fresnel regime

Author(s): Alexander Jesacher, Severin Fürhapter, Stefan Bernet, and Monika Ritsch-Marte

Abstract:

“We demonstrate a flexible setup for holographic steering of laser tweezers in microscopy using a high resolution spatial light modulator (SLM). In contrast to other methods, hologram read-out is done in the off-axis Fresnel regime rather than in the typically used on-axis Fourier regime. The diffractive structure is calculated as a Fresnel hologram, such that after reflection at the SLM only the desired first diffraction order is guided to the input of an optical microscope, where it generates a tailored optical tweezers field. We demonstrate some advantageous features of this setup, i.e. undesired diffraction orders are suppressed, the optical traps can be easily steered in real-time by just “mouse-dragging” a hologram window at the SLM display, and a number of independently steerable optical traps can be generated simultaneously in a three-dimensional arrangement by displaying a corresponding number of adjacent hologram windows at the SLM screen.”

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Publication: Optics Express
Issue/Year: Optics Express, Vol. 12, Issue 10, pp. 2243-2250, 2004
DOI: 10.1364/OPEX.12.002243

Real time opto-digital holographic microscopy (RTODHM)

Author(s): Larbi Bouamama, Mohamed Bouafia, Guenther Wernicke, Sven Krueger and Hartmut Gruber

Abstract:

“The high development of numerical image and signal processing techniques, may lead to the replacement of conventional photosensitive media used in holography by CCD sensors: hence, to the field of digital holography. The hologram is saved in the host memory of a computer and can be reconstructed on the same place or elsewhere in a numerical manner. The development of liquid crystal displays (LCD) directly addressed by computer permits to think of opto-digital holography. The observation of the reconstructed image at a limited distance is possible when using adequate optical components, which makes not only the possibility to observe the image at a defined distance but also to control its magnification (opto-digital holographic microscopy). Since it is possible to control all experimental steps by adequate software, it is then possible to make real time opto-digital holographic microscopy. In this work, we show the experimental set-up and the obtained results, showing that this technique can be used to study different kinds of materials, connected to different conventional microscopes and to make holographic interferometry.”

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Publication:Catalysis Today
Issue/Year: Catalysis Today, Volume 89, Issue 3, 30 March 2004, Pages 337-341, 2004
DOI: 10.1016/j.cattod.2003.12.017
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