Recently, the use of Bessel beams in evaluating the possibility of using them for a new generation of ground penetrating radar systems has been considered. Therefore, an analysis of the propagation of Bessel beams in conducting media is worthwhile. We present here an analysis of this type. Specifically, for normal incidence we analyze the propagation of a Bessel beam coming from a perfect dielectric and impinging on a conducting medium, i.e., the propagation of a Bessel beam generated by refracted inhomogeneous waves. The remarkable and unexpected result is that the incident Bessel beam does not change its shape even when propagating in the conducting medium.
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http://dx.doi.org/10.1364/AO.50.002654 | DOI Listing |
Biomed Phys Eng Express
December 2024
, Waseda University Graduate School of Information Production and Systems, Hibikino 2-7, Wakamatsu-ku, Kitakyushu 808-0135, JAPAN, Kitakyushu, 808-0135, JAPAN.
Recent studies on graph representation learning in brain tumor learning tasks have garnered significant interest by encoding and learning inherent relationships among the geometric features of tumors. There are serious class imbalance problems that occur on brain tumor MRI datasets. Impressive deep learning models like CNN- and Transformer-based can easily address this problem through their complex model architectures with large parameters.
View Article and Find Full Text PDFThe interaction between dual counter-propagating high-order circularly symmetric Bessel beams (CSBBs) and multi-layered chiral particles is investigated. Within the framework of generalized Lorenz-Mie theory (GLMT), the distribution characteristics of the superposition of two beams are studied based on the vector superposition theorem. The near-field, internal field, and far-field radar cross section (RCS) of the dual-layered chiral sphere illuminated by dual CSBBs are obtained according to the boundary conditions.
View Article and Find Full Text PDFIn this paper, the circular Bessel Gaussian beams (CBGBs) carrying power-cotangent-phase vortices are firstly introduced, whose propagation dynamics are explored theoretically and experimentally. The number of spiral lobes, rotation direction, rotation angle, and shape of the new type of beam can be flexibly modulated by controlling multiple parameters of power-cotangent-phase vortices. Accordingly, the effect of multiple beam parameters on abruptly autofocusing ability is quantified and compared by using the K-value curve that is described by ratio Im/I, where Im and I correspond to the maximum intensities at different propagation distance and the initial plane, respectively.
View Article and Find Full Text PDFThis paper is devoted to studying the Bessel beam propagation in cylindrical coordinates using the Hankel transform beam propagation method (HT-BPM) and their behavior in different scenarios in the microscale and meter scale of propagation distances. The study compares the results obtained from the HT-BPM with another fast Fourier transform beam propagation method (FFT-BPM) to validate the accuracy and effectiveness of the HT-BPM in modeling Bessel beam propagation. The axial intensity of Bessel beam propagation is analyzed using the HT-BPM.
View Article and Find Full Text PDFBessel beams with controllable output angles and uniform intensity distribution along the propagation direction have critical applications in many fields. This paper introduces a novel method to generate high uniformity, high signal-to-noise ratio, and angle-controllable Bessel beams by combining a Fresnel zone plate (FZP) with an axicon. An apodizing phase axicon with an ideally fitted profile is used, with a Gaussian beam as the light source.
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