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Fresnel zone

About: Fresnel zone is a research topic. Over the lifetime, 2337 publications have been published within this topic receiving 37650 citations.


Papers
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Journal ArticleDOI
TL;DR: The effects of quantization on the width of and power in the main lobe and the level of the sidelobes are studied and the results are cast in terms of normalized parameters and are applicable in general.
Abstract: Recently, various high-precision digital graphic systems have been used to generate patterns for diffractive and computer generated holographic optical elements. These plotting systems with submicron accuracy have a common drawback, namely, the patterns drawn have to be quantized. In this paper, the effects of pattern quantization on the optical beams are studied. Specifically, the fields of perfect cylindrical zone plates and cylindrical zone plates with quantized stripes are compared with that of conventional refractive cylindrical lenses. In particular, the effects of quantization on the width of and power in the main lobe and the level of the sidelobes are studied. The results are cast in terms of normalized parameters and are applicable in general.

5 citations

Patent
31 Mar 1988
TL;DR: In this article, the height of an uneven pattern of each Fresnel zone is set to a value for giving a phase shift of 2npi (n is a positive integer of >=2).
Abstract: PURPOSE:To facilitate the manufacture and to decrease the chromatic aberration by specifying the height of an uneven pattern in each Fresnel zone. CONSTITUTION:Height of an uneven pattern of each zone is set to a value for giving a phase shift of 2npi (n is a positive integer of >=2). Accordingly, a period of each zone becomes two times, comparing with a conventional Fresnel lens having a value for giving a phase shift whose height is 2pi. That is, even in case of the same numerical aperture NA, the period of each zone becomes (n) times by setting the height of the lens to (n) times. In such a way, the manufacture accuracy is improved, the lens efficiency is raised, and also, the period of the Fresnel zone is lengthened, by which a light beam is curved by a refraction rather than a diffraction effect, and a chromatic aberration caused by a use wavelength variation is decreased.

5 citations

Journal ArticleDOI
TL;DR: In this paper, non-coherent holograms of two-dimensional dilute objects using on-axis and off-axis Fresnel zone plates (FZP) were formed and reconstruction attempted in noncoherent light.
Abstract: Noncoherent holograms of two-dimensional dilute objects using on-axis and off-axis Fresnel zone plates (FZP) were formed and reconstruction attempted in noncoherent light. Using this type of illumination for both stages of the process, we devised a method of suppressing the dc bias.

5 citations

Journal ArticleDOI
Germain Boivin1
TL;DR: In typical experiments with narrow field objects, it is shown that the zone plate behaves like a diffraction-limited lens, the gain in resolution is noticeable as the wavelength decreases, the use of the third-order focus improves the resolution of the system, and under certain conditions the depth of field can be increased without loss of resolution.
Abstract: The feasibility of optical systems for short wavelength radiations ranging from the near uv to soft x rays is supported by theoretical and experimental arguments. The major problem of absorption of these radiations by materials has been overcome in the near and middle uv by using the lens properties of a Fresnel zone plate generated on a thin self-supporting film. In typical experiments with narrow field objects, it is shown that the zone plate behaves like a diffraction-limited lens, the gain in resolution is noticeable as the wavelength decreases, the use of the third-order focus improves the resolution of the system, and under certain conditions the depth of field can be increased without loss of resolution. The chromatic aberrations of the zone plate are not restrictive for a large number of applications.

5 citations

Proceedings ArticleDOI
07 Jun 1999
TL;DR: In this article, the authors proposed a fast algorithm for computing traveltimes like FD techniques, but this algorithm does not yield amplitudes and they usually must be calculated by the slower ray methods (dynamic ray tracing).
Abstract: Geometrical spreading plays an important role for various applications, e.g. true amplitude migration, estimation of Fresnel zones, divergence corrections. Unfortunately, fast algorithms for computing traveltimes like FD techniques do not yield amplitudes. They usually must be calculated by the slower ray methods (dynamic ray tracing).

5 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
202326
202249
202137
202052
201965
201878