Results 121 to 130 of about 87,657 (169)

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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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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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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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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A Millimeter-Wave Fresnel Zone Plate Lens Design Using Perforated 3D Printing Material

IEEE MTT-S International Microwave Workshop Series on Advanced Materials and Processes for RF and THz Applications, 2018
This paper presents a novel Fresnel Zone Plate Lens (FZPL) using perforated 3D printing material at 60 GHz$\lambda_\mathrm {0} = \mathrm {5.45 mm}$. A gradient refractive index condition is controlled using the air-hole approach in the dielectric slab ...
J. Pourahmadazar, Sara Sahebghalam, S. Abazari Aghdam, M. Nouri   +3 more
semanticscholar   +1 more source

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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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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Fresnel zone plates for two wavelengths

SPIE Proceedings, 1995
This paper proposes two systems of Fresnel Zone Plates which could focus two parallel monochromatic and coherent beams (with different wavelengths), eliminating the wellknown chromatical aberrations of the classical construction.
Eugene O. Curatu, Roxana N. Radvan, Roxana Savastru   +2 more
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