Results 131 to 140 of about 1,516 (173)

Optimization of modified volume Fresnel zone plates

Journal of the Optical Society of America A, 2009
Modified volume Fresnel zone plates (MVFZPs) fabricated with laser direct writing were optimized for higher diffraction efficiencies. The Fresnel radii in each layer of a volume zone plate were iteratively adjusted by a simulation-based direct search optimization.
Srisungsitthisunti, Pornsak, Ersoy, Okan, Xu, Xianfan   +2 more
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Variations on the Fresnel Zone Plate

Journal of the Optical Society of America, 1966
The effects of contrast in the Fresnel zone plate on the amplitude in the focal point due to a normally incident plane wave are obtained by direct evaluation of the Fresnel–Kirchhoff diffraction integral. The change in focal-point amplitude due to smoothing the ordinary, discontinuous, “square-wave” transmission function into a continuous, “sine-wave ...
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Fresnel Zone Plate and Fresnel Phase Plate Patterns for Acoustic Transducers

1984
An ultrasonic transducer with an electrode pattern in the shape of a Fresnel zone plate (FZP) is useful in acoustic imaging. However a major problem in focusing with an FZP is that the final image will have a large zero-order component and this will restrict the dynamic range of the system.
M. Mortezaie, G. Wade
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Imaging and focusing of atoms by a fresnel zone plate

Physical Review Letters, 1991
Focusing of and imaging with atoms by means of a spherical Fresnel zone plate has been observed for the first time. An intense beam of metastable helium atoms with atomic de Broglie wavelength ${\ensuremath{\lambda}}_{\mathrm{dB}}$=0.5--2.5 \AA{} is passed through either a single or a double slip with dimensions in the 10-\ensuremath{\mu}m range.
, Carnal, , Sigel, , Sleator, , Takuma, , Mlynek   +4 more
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Quantum Noise in Fresnel Zone Plate Imaging

Applied Optics, 1974
A Fresnel zone plate, used as a coded aperture, offers a great advantage in geometric collection efficiency over a conventional pinhole or collimator. We present a detailed analysis of the signal-to-noise ratio (SNR) of a quantum-limited zone plate camera.
H H, Barrett, G D, Demeester
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Focalization of Fresnel-Cantor zone plates

SPIE Proceedings, 2003
We extend the results obtained for different cases of the product superposition between periodic functions to the case of circular symmetry. The characteristics of focalization for such case is studied. We name Fresnel-Cantor zone plate to the structures obtained.
Diana E. Calva Mendez, Mario M. Lehman
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The elliptical Fresnel-zone plate antenna

Ninth International Conference on Antennas and Propagation (ICAP), 1995
The growing number of direct broadcast satellites (DBS) asks for simple, low-cost home receiving systems. The use of the Fresnel-zone plate antenna (FZPA), which is related to the optical lens, is also promising for this application. The aperture of the FZPA is plane and its structure is determined by the well-known Fresnel ellipsoids.
van Houten, J.M., Herben, M.H.A.J.
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Optimization of polygonal Fresnel zone plates

Microwave and Optical Technology Letters, 2007
AbstractThe performance of Fresnel zone plates having polygonal boundaries between zones has been studied for polygons with a low number of sides. An optimized polygonal shape has been analytically defined by minimizing the mismatched area between the circular and the polygonal pseudo‐Fresnel zones.
Alda, Javier, Boreman, Glenn
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Acoustic Fresnel zone plate transducers

Applied Physics Letters, 1974
Experimental focal plane intensity distributions are presented for a 10-zone acoustic zone plate operating at approximately 10 MHz. The results are related to the spatial frequency response of the transducer. Some initial imaging experiments with this transducer are described along with preliminary results for an acoustic phase plate.
S. A. Farnow, B. A. Auld
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Solid immersion Fresnel zone plate

Digital Holography & 3-D Imaging Meeting, 2015
A solid immersion Fresnel zone plate (SIFZP) is designed and its near-field imaging characteristics are analyzed using the vector angular spectrum method. Results show SIFZP can generate a high intensity and subwavelength focus.
Yaoju Zhang, Xiao Qian, Xiukai Ruan, Haiyong Zhu   +3 more
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