Applications of the high-resolution optical reconstruction of digital holograms

Author(s): Günther Wernicke, Johannes Frank, Hartmut Gruber, Matthias Dürr, Andreas Langner, Stefan Eisebitt, Christian Günther, Larbi Bouamama, Sven Krüger and Andreas Hermerschmidt

Abstract:

“Adressable spatial light modulators with as much as possible ideal phase modulation are the precondition for their application in digital holography. An adapted driver electronics for the modulator and a correct knowledge of the modulation behavior can lead to a dynamic phase modulating device with nearly linear characteristic curve and a maximum phase range of 2pi. We show a system for recording and reconstruction of digital holograms applying a spatial light modulator for the optical reconstruction and the digital processing of the holograms. The data of a CCD-camera are taken to a PC and sent to a spatial light modulator. In that sense we realised an analog-digital converter for recording and a digital-analog converter for the optical hologram reconstruction. We discuss the resolution of the reconstruction and their applications, especially possibilities for the manipulation with the reconstructed wave field. ”

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Publication: SPIE Proceedings
Issue/Year: Proc. SPIE, Vol. 6136, 61360Q (2006)
DOI: 10.1117/12.651622

Optimally tuned spatial light modulators for digital holography

Author(s): Christian Kohler, Xavier Schwab, and Wolfgang Osten

Abstract

“Digital holography and comparative digital holography are applications that require computer-addressable modulators for the optical reconstruction of digital holograms. The quality of the reconstructed holograms depends on the modulator’s properties. Therefore a characterization of the modulators is required. We show the result of a modulator characterization and the modulator’s influence on the quality of the reconstructed hologram. We then compare qualitatively and quantitatively the optical reconstruction of phase and amplitude holograms by considering their level of detail and their diffraction efficiency.”

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Publication: Applied Optics
Issue/Year: Applied Optics, Vol. 45, Issue 5, pp. 960-967 (2006)
DOI: 10.1364/AO.45.000960

Fast digital hologram generation and adaptive force measurement in liquid-crystal-display-based holographic tweezers

Author(s): Marcus Reicherter, Susanne Zwick, Tobias Haist, Christian Kohler, Hans Tiziani, and Wolfgang Osten

Abstract:

“Computer-generated holograms in conjunction with spatial light modulators (SLMs) offer a way to dynamically generate holograms that are adapted to specific tasks. To use the full dynamic capability of the SLM, the hologram computation should be very fast. We present a method that uses the highly parallel architecture of a consumer graphics board to compute analytical holograms in video real time. A precice characterization of the SLM (Holoeye LC-R-2500) and the adaption of its settings to our near-infrared application is necessary to guarantee an efficient hologram reconstruction. The benefits of a fast computation of adapted holograms and the application of an efficient SLM are demonstrated by measuring the trapping forces of holographic tweezers.”

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Publication: Applied Optics
Issue/Year: Applied Optics, Vol. 45, Issue 5, pp. 888-896, 2006
DOI: 10.1364/AO.45.000888

Real-time digital holographic beam-shaping system with a genetic feedback tuning loop

Author(s): Joonku Hahn, Hwi Kim, Kyongsik Choi, and Byoungho Lee

Abstract:

“A novel implementation of a real-time digital holographic system with a genetic feedback tuning loop is proposed. The proposed genetic feedback tuning loop is effective in encoding optimal phase holograms on a liquid-crystal spatial light modulator in the system. Optimal calibration of the liquid-crystal spatial light modulator can be achieved via the genetic feedback tuning loop, and the optimal phase hologram can then overcome the aberration of the internal optics of the system.”

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Publication: Applied Optics
Issue/Year: Applied Optics, Vol. 45, Issue 5, pp. 915-924, 2006
DOI: 10.1364/AO.45.000915

Residue orbital angular momentum in interferenced double vortex beams with unequal topological charges

Author(s): S. H. Tao, X.-C. Yuan, J. Lin, and R. E. Burge

Abstract:

“When two vortex beams with unequal topological charges superpose coherently, orbital angular momentum (OAM) in the two beams would not be cancelled out completely in the interference. The residual OAMs contained by the superposed beam are located at different concentric rings and may have opposite orientations owing to the difference of the charges. The residual OAM can be confirmed by the rotation of microparticles when difference between the charges of two interfering beams is large.”

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Publication: Optics Express
Issue/Year: Optics Express, Vol. 14, Issue 2, pp. 535-541, 2006
DOI: 10.1364/OPEX.14.000535

Dynamic closed-loop system for focus tracking using a spatial light modulator and a deformable membrane mirror

Author(s): Amanda J. Wright, Brett A. Patterson, Simon P. Poland, John M. Girkin, Graham M. Gibson, and Miles J. Padgett

Abstract:

“A dynamic closed-loop method for focus tracking using a spatial light modulator and a deformable membrane mirror within a confocal microscope is described. We report that it is possible to track defocus over a distance of up to 80 µm with an RMS precision of 57 nm. For demonstration purposes we concentrate on defocus, although in principle the method applies to any wavefront shape or aberration that can be successfully reproduced by the deformable membrane mirror and spatial light modulator, for example, spherical aberration.”

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Publication: Optics Express
Issue/Year: Optics Express, Vol. 14, Issue 1, pp. 222-228, 2006
DOI: 10.1364/OPEX.14.000222

Collinear superposition of multiple helical beams generated by a single azimuthally modulated phase-only element

Author(s): J. Lin, X.-C. Yuan, S. H. Tao, and R. E. Burge

Abstract:

“We propose a highly efficient approach to generating multihelix beams that contain more than one helical mode, and the power distribution over helical modes is adjustable. A multihelix beam embedded with three collinear helical modes is demonstrated by use of a spatial light modulator.”

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Publication: Optics Letters
Issue/Year: Optics Letters, Vol. 30, Issue 24, pp. 3266-3268, 2006
DOI: 10.1364/OL.30.003266

Femtosecond laser ablation elemental mass spectrometry

Author(s): Roland Hergenröder, Ota Samek, Vanja Hommes

Abstract:

“Laser ablation mass spectrometry (LA-MS) has always been an interesting method for the elemental analysis of solid samples. Chemical analysis with a laser requires small amounts of material. Depending on the analytical detection system, subpicogram quantities may be sufficient. In addition, a focused laser beam permits the spatial characterization of heterogeneity in solid samples typically with micrometer resolution in terms of lateral and depth dimensions. With the advent of high-energy, ultra-short pulse lasers, new possibilities arise. The task of this review is to discuss the principle differences between the ablation process of short (>1 ps) and ultra-short (<1 ps) pulses. Based on the timescales and the energy balance of the process that underlies an ablation event, it will be shown that ultra-short pulses are less thermal and cause less collateral damages than longer pulses. The confinement of the pulse energy to the focal region guarantees a better spatial resolution in all dimensions and improves the analytical figures of merit (e.g., fractionation). Applications that demonstrate these features and that will be presented are in-depth profiling of multi-layer samples and the elemental analysis of biological materials.”

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Publication: Mass Spectrometry Reviews
Issue/Year: Mass Spectrometry Reviews, Volume 25, Issue 4 , Pages 551 – 572 (2005)
DOI: 10.1002/mas.20077

Accurate encoding of arbitrary complex fields with amplitude-only liquid crystal spatial light modulators

Author(s): Victor Arrizón, Guadalupe Méndez, and David Sánchez-de-La-Llave

Abstract:

“We show that computer generated holograms, implemented with amplitude-only liquid crystal spatial light modulators, allow the synthesis of fully complex fields with high accuracy. Our main discussion considers modified amplitude holograms whose transmittance is obtained by adding an appropriate bias function to the real cosine computer hologram of the encoded signal. We first propose a bias function, given by a soft envelope of the signal modulus, which is appropriate for perfect amplitude modulators. We also consider a second bias term, given by a constant function, which results appropriate for modulators whose amplitude transmittance is coupled with a linear phase modulation. The influence of the finite pixel size of the spatial light modulator is compensated by digital pre-filtering of the encoded complex signal. The performance of the discussed amplitude CGHs is illustrated by means of numerical simulations and the experimental synthesis of high order Bessel beams.”

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Publication: Optics Express
Issue/Year: Optics Express, Vol. 13, Issue 20, pp. 7913-7927, 2005
DOI: 10.1364/OPEX.13.007913

Fractional optical vortex beam induced rotation of particles

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

Abstract:

“We experimentally demonstrate optical rotation and manipulation of microscopic particles by use of optical vortex beams with fractional topological charges, namely fractional optical vortex beams, which are coupled in an optical tweezers system. Like the vortex beams with integer topological charges, the fractional optical vortex beams are also capable of rotating particles induced by the transfer of orbital angular momentum. However, the unique radial opening (low-intensity gap) in the intensity ring encompassing the dark core, due to the fractional nature of the beam, hinders the rotation significantly. The fractional vortex beams orbital angular momentum and radial opening are exploited to guide and transport microscopic particles.”

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Publication: Optics Express
Issue/Year: Optics Express, Vol. 13, Issue 20, pp. 7726-7731, 2005
DOI: 10.1364/OPEX.13.007726
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