Topic
Fresnel zone
About: Fresnel zone is a research topic. Over the lifetime, 2337 publications have been published within this topic receiving 37650 citations.
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TL;DR: The general astigmatic transform, or two-dimensional non-separable linear canonical transform of a Hermite-Laguerre-Gaussian beam, is investigated by theoretical means.
Abstract: The general astigmatic transform, or two-dimensional non-separable linear canonical transform of a Hermite-Laguerre-Gaussian beam, is investigated by theoretical means. Some corollaries that apply to Hermite-Gaussian and Laguerre-Gaussian beam propagation are presented and discussed.
33 citations
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TL;DR: In this paper, a generalized form of spectral representation theory is developed and used with the ABCD formulation of the Huygens-Fresnel integral for studying optical wave propagation through a random medium.
Abstract: A generalized form of spectral representation theory is developed and used with the ABCD formulation of the Huygens–Fresnel integral for studying optical wave propagation through a random medium in the presence of any complex paraxial optical system that can be characterized by an ABCD ray matrix. Formal expressions are developed for the basic optical field moments and various related second-order statistical quantities in terms of three fundamental moments of the first- and second-order complex phase perturbations. Special propagation environments include line-of-sight propagation, single-pass propagation through arbitrary ABCD optical systems, and double-pass propagation through the same random medium in the presence of an ABCD optical system. For illustrative purposes the method is used in the development of expressions for the mean and the normalized variance of the irradiance associated with the Fourier-transform-plane geometry of a lens and the enhanced backscatter effect (EBS) associated with irradiance and phase fluctuations of a reflected Gaussian-beam wave from a Gaussian mirror. The EBS analysis accounts for both finite size and finite focal length of the mirror.
33 citations
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TL;DR: In this article, the diffraction pattern of electromagnetic waves at distances from zero to five wave-lengths from a circular aperture was studied at distances ranging from 0 to 5 wave lengths.
Abstract: The diffraction pattern of electromagnetic waves was studied at distances from zero to five wave-lengths from a circular aperture. Microwaves of 12.8-cm wave-length were employed. The aperture was an iris diaphragm that could be varied between one and six wave-lengths in diameter. The beam was incident normally upon the plane of the aperture from a 4 ft parabolic reflector 24 feet away. The sharpest diffraction patterns were in the plane of the aperture. Measurements were made of the intensity of radiation in the electric and magnetic planes through the axis. Individual plots were made of intensities along the diameter and along lines parallel to the diameter at steps of quarter wave-lengths from the diameter. Measurements were also made of the intensities at fixed points along the axis as the diameter of the iris was varied from one to six wave-lengths. It was observed that Fresnel zone theory could be employed as a rule of thumb in predicting the intensity along the axis even in the illogical case of predicting the intensity at the center of the aperture. Checks were made against Kirchhoff's theory.
33 citations
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TL;DR: A theoretical analysis and numerical simulations based on the Rayleigh-Sommerfeld approach have been developed analyzing properties such as the depth of focus and the intensity of the focus in terms of the number of zones as discussed by the authors.
33 citations
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TL;DR: In this paper, the amplitude scintillation measurements made on two-millimeter microwave links at 36 GHz and 110 GHz along a common 4.1 km path across central London are deseribed.
Abstract: Amplitude scintillation measurements made on two-millimeter microwave links at 36 GHz and 110 GHz along a common 4.1 km path across central London are deseribed. The variances of the logarithmic amplitude scintilliations at these two frequencies are compared for different ranges of the outer scale of turbulence. A comparison is made between the experimental results and the theoretical predictions of Tatarski. Good agreement has been found for the two cases when the outer scale of turbulence is greater than and smaller than the Fresnel zone size.
33 citations