Computer-generated holograms (CGH's) of phase modulation type have been designed and fabricated in the biological material Bacteriorhodopsin (BR). BR is a photochromic retinal protein which may be used in optical ...
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ISBN:
(纸本)0819452130
Computer-generated holograms (CGH's) of phase modulation type have been designed and fabricated in the biological material Bacteriorhodopsin (BR). BR is a photochromic retinal protein which may be used in optical data storage and security applications. Using the permanent light-inducible refractive index change of BR, we demonstrate that both analog and digital optical data can be stored in this material in a write-once-read-many (WORM) mode. The calculation and the optimization of the phase function of the CGH's have been accomplished with iterative Fourier transform algorithm methods (IFTA) such as error reduction algorithms. In the fabrication procedure the optimized phase functions of the CGH's have been recorded in BR which was coated onto a glass substrate. A direct laser writing process employing the 532 nm line of a cw-Nd:YAG laser was used for recording the CGH as a modulation of the absorption coefficient as well as of the refractive index. The design and fabrication method of the CGHs with a pixel pitch of 20 mum and a total size of 10 mm x 10 mm are presented.
Three-dimensional beam forming is an important task for various applications, e.g., optical scanners and imaging systems. However, optical beams satisfy the wave equation when propagating in free-space, meaning that n...
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Three-dimensional beam forming is an important task for various applications, e.g., optical scanners and imaging systems. However, optical beams satisfy the wave equation when propagating in free-space, meaning that not any prescribed 3-D distribution is a physical light beam. This paper proposes an iterative algorithm for synthesizing 3-D optical beams that satisfy the wave equation. The algorithm is based on a close inspection at the Fourier transform of optical beams, which involves Ewald's surfaces. It utilizes the error-reductionalgorithm that exploits the degrees of freedom existing in the optical system. (C) 2003 Elsevier B.V. All rights reserved.
Two algorithms for the synthesis of a microwave beam with desired characteristics are discussed. The beam is composed by an array of either identical or non-identical antennas. In an example, the application of those ...
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Two algorithms for the synthesis of a microwave beam with desired characteristics are discussed. The beam is composed by an array of either identical or non-identical antennas. In an example, the application of those algorithms for wireless power transmission is demonstrated.
A modified Fourier phase retrieval algorithm is proposed to reconstruct an object from a severe noise corrupted modulus. Both of the noise upper and lower level limits and occupied area are used to formulate noise con...
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A modified Fourier phase retrieval algorithm is proposed to reconstruct an object from a severe noise corrupted modulus. Both of the noise upper and lower level limits and occupied area are used to formulate noise constraints in the algorithm. This algorithm is shown to be desirable when the noise level is high. Ein modifizierter algorithmus wird vorgeschlagen, der zu einem durch Rauschen stark gestörten Betragsspektrum die Phase und damit ein zugehöriges Objekt wiederherstellt. Einschränkende Bedingungen an das für den algorithmus zugelassene Rauschen werden formuliert; dazu werden sowohl die Ober- und Untergrenzen des Störniveaus als auch die eingenommene Fläche herangezogen. Es wird gezeigt, daβ der algorithmus im Falle starker Störungen vorteilhaft ist. Nous proposons dans cet article un algorithme modifié de recouvrement de phase de Fourier permettant de reconstruire un objet à partir du module sévérement corrompu par le bruit. Les limites inférieure et supérieure de niveau du bruit ainsi que l'aire occupée sont à la fois utilisées pour formuler les contraintes de bruit dans cet algorithme. Nous montrons que celui-ci est approprié quand le niveau de bruit est élevé.
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