Optically based manufacturing with polymer particles

Author(s): Reza Ghadiri, Mario Surbek, Cemal Esen, Andreas Ostendorf.

Abstract:

“We present a new single-laser optical trapping technique for the exact manipulation and durable assembly of transparent polymer microparticles. This technique comprises the trapping of microparticles and the assembly by using a laser-driven thermal process for the joining of the particles. The thermal energy necessary for the systematic joining is applied partly by global heating of the processing chamber and by absorption of the electromagnetic radiation of the laser tweezer. The main advantage of this contact free joining technology is to use the same laser for the optical trapping, positioning and the durable assembly. The generated joints are stable and cannot be broken up with optical forces. In summary, a new micromanufacturing process based on an optical machining process is reported with promising applications in the MEMS and photonics area.”

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Publication: Physics Procedia
Issue/Year: Physics Procedia, Volume 5, Part A, Pages 47–51, (2010)
DOI: 10.1016/j.phpro.2010.08.121

Optical control and dynamic patterning of zeolites

Author(s): Mike Woerdemann, Christina Alpmann, Florian Hörner, Cornelia Denz, André Devaux and Luisa De Cola

Abstract:

“Zeolite crystals have a wide use as model systems for artificial light harvesting systems, as nano-containers for supramolecular organization or as building blocks for 1D and 2D assemblies of several crystals. In particular the assembly of zeolite L crystals with the aim to bridge the gap between the nano- and the macroscopic world has been a focus of research during the last years. However, almost all available approaches to order, assemble and pattern Zeolite L are restricted to large amounts of crystals. Although these approaches have proven to be powerful for many applications, but they have only limited control over positioning or orientation of single crystals and are lacking if patterns or structures are required which are composed of a few or up to a few hundred individual crystals. We demonstrate here that holographic optical tweezers are a powerful and versatile instrument to control zeolite L on the single crystal level. It is shown that full three-dimensional positioning, including rotational control, of any zeolite L crystal can be achieved. Finally, we demonstrate fully reversible, dynamic patterning of a multitude of individually controlled zeolite L crystals.”

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Publication: SPIE Proceedings
Issue/Year: Proc. SPIE, Volume 7762, 77622E, (2010)
DOI: 10.1117/12.863610

Application of cooled spatial light modulator for high power nanosecond laser micromachining

Author(s): Rainer J. Beck, Jonathan P. Parry, William N. MacPherson, Andrew Waddie, Nick J. Weston, Jonathan D. Shephard, and Duncan P. Hand

Abstract:

“The application of a commercially available spatial light modulator (SLM) to control the spatial intensity distribution of a nanosecond pulsed laser for micromachining is described for the first time. Heat sinking is introduced to increase the average power handling capabilities of the SLM beyond recommended limits by the manufacturer. Complex intensity patterns are generated, using the Inverse Fourier Transform Algorithm, and example laser machining is demonstrated. The SLM enables both complex beam shaping and also beam steering.”

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Publication: Optics Express
Issue/Year: Optics Express, Vol. 18, Issue 16, pp. 17059-17065 (2010)
DOI: 10.1364/OE.18.017059

The Applications and Technology of Phase-Only Liquid Crystal on Silicon Devices

Author(s): Collings, N.; Davey, T.; Christmas, J.; Chu, D.; Crossland, B.

Abstract:

“An introduction to the technology of liquid crystal on silicon (LCOS) devices leads on to a discussion of the application areas which have been and are being opened up by the development of phase-only devices.”

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Publication: Journal of Display Technology
Issue/Year: Journal of Display Technology, Vol. 7, Issue 3, pp. 112-119 (2010)
DOI: 10.1109/JDT.2010.2049337

A portable laser photostimulation and imaging microscope

Author(s): Volodymyr Nikolenko , Darcy S Peterka, Rafael Yuste

Abstract:

“We describe a compact microscope that uses a spatial light modulator (SLM) to control the excitation laser light. The flexibility of SLMs, which can mimic virtually any optical transfer function, enables the experimenter to create, in software, arbitrary spatio-temporal light patterns, including focusing and beam scanning, simply by calculating the appropriate phase mask. Our prototype, a scan-less device with no moving parts, can be used for laser imaging or photostimulation, supplanting the need for an elaborate optical setup. As a proof of principle, we generate complex excitation patterns on fluorescent samples and also perform functional imaging of neuronal activity in living brain slices.”

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Publication: Journal of Neural Engineering
Issue/Year: J. Neural Eng., Volume 7, Number 4 (2010) 045001
DOI: 10.1088/1741-2560/7/4/045001

Reconfigurable all-diffractive optical filters using phase-only spatial light modulators

Author(s): Gladys Mínguez-Vega, V. R. Supradeepa, Omel Mendoza-Yero, Andrew M. Weiner

Abstract:

“We demonstrate a reconfigurable optical filter implemented using a phase-only two-dimensional liquid-crystal-on-silicon spatial light modulator. To achieve this we utilize two different approaches leading to two different configurations in the modulator. The first one, based on a spatially patterned diffractive lens, permits us to obtain the desired spectrum along the optical axis and, in the second one, which is based on a generalized spectrometer, the desired spectrum is found outside of the optical axis. Experimental results show good agreement with the theory and indicate the validity of this technique.”

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Publication: Optics Letters
Issue/Year: Optics Letters, Vol. 35, Issue 14, pp. 2406-2408 (2010)
DOI: 10.1364/OL.35.002406

Optical encryption based on computational ghost imaging

Author(s): Pere Clemente, Vicente Durán, Víctor Torres-Company, Enrique Tajahuerce, Jesús Lancis

Abstract:

“Ghost imaging is an optical technique in which the information of an object is encoded in the correlation of the intensity fluctuations of light. The computational version of this fascinating phenomenon emulates, offline, the optical propagation through the reference arm, enabling 3D visualization of a complex object whose transmitted light is measured by a bucket detector. In this Letter, we show how computational ghost imaging can be used to encrypt and transmit object information to a remote party. Important features, such as key compressibility and vulnerability to eavesdropping, are experimentally analyzed.”

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Publication: Optics Letters
Issue/Year: Optics Letters, Vol. 35, Issue 14, pp. 2391-2393 (2010)
DOI: 10.1364/OL.35.002391

Full 3D translational and rotational optical control of multiple rod-shaped bacteria

Author(s): Florian Hörner, Mike Woerdemann, Stephanie Müller, Berenike Maier, Cornelia Denz

Abstract:

“The class of rod-shaped bacteria is an important example of non-spherical objects where defined alignment is desired for the observation of intracellular processes or studies of the flagella. However, all available methods for orientational control of rod-shaped bacteria are either limited with respect to the accessible rotational axes or feasible angles or restricted to one single bacterium. In this paper we demonstrate a scheme to orientate rod-shaped bacteria with holographic optical tweezers (HOT) in any direction. While these bacteria have a strong preference to align along the direction of the incident laser beam, our scheme provides for the first time full rotational control of multiple bacteria with respect to any arbitrary axis. In combination with the translational control HOT inherently provide, this enables full control of all three translational and the two important rotational degrees of freedom of multiple rod-shaped bacteria and allows one to arrange them in any desired configuration.”

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Publication: Journal of Biophotonics
Issue/Year: Journal of Biophotonics, Volume 3, Issue 7, pages 468–475, July 2010
DOI: 10.1002/jbio.201000033

Optical reconstruction of digital holograms recorded at 10.6 μm: route for 3D imaging at long infrared

Author(s): Melania Paturzo, Anna Pelagotti, Andrea Finizio, Lisa Miccio, Massimiliano Locatelli, Andrea Gertrude, Pasquale Poggi, Riccardo Meucci, Pietro Ferraro

Abstract:

“We demonstrate the optical reconstruction in the visible range (0.532μm) of digital holograms recorded at long IR wavelengths (10.6μm) by means of a spatial light modulator. By using an integrated recording-reconstruction system, it is, in fact, feasible to achieve direct imaging of holograms acquired outside the visible range, i.e., in the IR spectrum. By choosing a Fourier recording configuration, the reconstructed image, obtained at about a 20 times shorter wavelength than the acquisition image, exhibits minor aberrations, which do not significantly affect the optical reconstruction. The high NA achievable at a long IR wavelength allows us to image large objects at reasonable distances.”

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Publication: Optics Letters
Issue/Year: Optics Letters, Vol. 35, Issue 12, pp. 2112-2114 (2010)
DOI: 10.1364/OL.35.002112

Advanced Scanning Laser-Doppler Vibrometer with Computer Generated Holograms

Author(s): S. Zwick, M. Warber, T. Haist, F. Schaal, W. Osten, S. Boedecker, and C. Rembe

Abstract:

“In this paper we present a novel technique for steering the beam of a scanning laser-Doppler vibrometer (LDV) using a Spatial Light Modulator (SLM). Computer Generated Holograms (CGH) are employed to obtain the phase maps displayed by the SLM. Due to this approach, spurious diffraction orders are generated. We present concepts to suppress these diffraction orders so as to realize a scanning vibrometer. We discuss the properties and limitations of this solution. Different SLMs have been evalutated and a compact scanning vibrometer based on a Holoeye Pluto SLM has been realized. First measurement results are presented. In addition, we demonstrate simulations on the reduction of speckle related signal dropouts. Drop-Outs can be reduced by adapting the measurement-beam wavefront with the CGH to maximize the light power collected with the vibrometer aperture. We have explored an approach to optimize the signal strength by adapting the coefficients of the Zernike polynomials of an additional wavefront shift.”

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Publication: AIP Conference Proceedings
Issue/Year: AIP Conf. Proc., Volume 1253, pp. 279-290, May 28, 2010
DOI: 10.1063/1.3455467