A three dimensional dark focal spot uniformly surrounded by light

2007 ◽  
Vol 279 (2) ◽  
pp. 229-234 ◽  
Author(s):  
Nándor Bokor ◽  
Nir Davidson
Keyword(s):  
Focal Spot ◽  
Three Dimensional

Three-dimensional acoustic sub-diffraction focusing by coiled metamaterials with strong absorption

2019 ◽  
Vol 7 (17) ◽  
pp. 5131-5138 ◽  
Author(s):  
Fuyin Ma ◽  
Jianyu Chen ◽  
Jiu Hui Wu
Keyword(s):  
Focal Spot ◽  
Three Dimensional ◽  
Homogeneous Medium ◽  
Diffraction Limit ◽  
Strong Absorption ◽  
Operating Wavelength

The diffraction limit restricts the smallest diameter of a wave's focal spot in a homogeneous medium to no less than half of the operating wavelength.

scholarly journals High energy density physics problems related to liquid jet lithium target for Super-FRS fast extraction scheme

2007 ◽  
Vol 25 (2) ◽  
pp. 295-304 ◽  
Author(s):  
N.A. Tahir ◽  
V. Kim ◽  
I.V. Lomonosov ◽  
D.A. Grigoriev ◽  
A.R. Piriz ◽  
...  
Keyword(s):  
Focal Spot ◽  
Three Dimensional ◽  
Extended Period ◽  
High Energy ◽  
High Energy Density ◽  
Liquid Lithium ◽  
Liquid Jet ◽  
Fragment Separator ◽  
Uranium Beam ◽  
Lithium Target

The new international facility for antiproton and ion research (FAIR), at Darmstadt, Germany, will accelerate beams of all stable isotopes from protons up to uranium with unprecedented intensities (of the order of 1012 ions per spill). Planned future experiments include production of exotic nuclei by fragmentation/fission of projectile ions of different species with energies up to 1.5 GeV/u at the proposed super conducting fragment separator, Super-FRS. In such experiments, the production target must survive multiple irradiations over an extended period of time, which in case of such beam intensities is highly questionable. Previous work showed that with full intensity of the uranium beam, a solid graphite target will be destroyed after being irradiated once, unless the beam focal spot is made very large that will result in extremely poor transmission and resolution of the secondary isotopes. An alternative to a solid target could be a windowless liquid jet target. We have carried out three-dimensional numerical simulations to study the problem of target heating and propagation of pressure in a liquid Li target. These first calculations have shown that a liquid lithium target may survive the full uranium beam intensity for a reasonable size focal spot.

scholarly journals Near-Field Diffraction from a Binary Microaxicon

2012 ◽  
Vol 2012 ◽  
pp. 1-11 ◽  
Author(s):  
Victor V. Kotlyar ◽  
Sergey S. Stafeev ◽  
Roman V. Skidanov ◽  
Victor A. Soifer
Keyword(s):  
Finite Difference ◽  
Focal Spot ◽  
Optical Axis ◽  
Near Field ◽  
Three Dimensional ◽  
Finite Difference Schemes ◽  
Cylindrical Coordinates ◽  
Linearly Polarized ◽  
Experimental Values ◽  
Good Agreement

We study binary axicons of period 4, 6, and 8 μm fabricated by photolithography with a 1 μm resolution, 500 nm depth, and 4 mm diameter. Near-field diffraction focal spots varying in diameter from 3.5λ to 4.5λ (for the axicon of period T=4 μm) and from 5λ to 8λ (for the axicon with T=8 μm) are experimentally found on the optical axis at a distance of up to 40 μm from the axicon for the wavelength λ=0.532 μm. The first focal spot is found at distance 2 μm (T=4 μm), with the period of the focal spots being 2 μm (T=4 μm) and 4 μm (T=8 μm). Diffraction of linearly polarized plane and diverging waves is simulated using FullWAVE (RSoft) and a proprietary program BOR-FDTD, which implement finite-difference schemes to solve three-dimensional Maxwell's equations in the Cartesian and cylindrical coordinates. The numerically simulated values for diameters of the near-field focal spots for the axicon of period T=4 μm are in good agreement with the experimental values.

scholarly journals Three-dimensional shape-controllable focal spot array created by focusing vortex beams modulated by multi-value pure-phase grating

2014 ◽  
Vol 22 (18) ◽  
pp. 21354 ◽  
Author(s):  
Linwei Zhu ◽  
Meiyu Sun ◽  
Mengjun Zhu ◽  
Jiannong Chen ◽  
Xiumin Gao ◽  
...  
Keyword(s):  
Focal Spot ◽  
Three Dimensional ◽  
Phase Grating ◽  
Pure Phase ◽  
Dimensional Shape ◽  
Vortex Beams ◽  
Three Dimensional Shape ◽  
Spot Array

Theoretical prediction of three-dimensional shifting of a spherical focal spot in a 4Pi focusing system

2012 ◽  
Vol 14 (5) ◽  
pp. 055706 ◽  
Author(s):  
Ze Li ◽  
Shaohui Yan ◽  
Baoli Yao ◽  
Ming Lei ◽  
Baiheng Ma ◽  
...  
Keyword(s):  
Theoretical Prediction ◽  
Focal Spot ◽  
Three Dimensional

Creation of a three-dimensional super-resolution transversally polarized focal spot by 4π tight focusing of radially polarized vortex beams

2015 ◽  
Vol 17 (5) ◽  
pp. 055605 ◽  
Author(s):  
Zhongquan Nie ◽  
Guang Shi ◽  
Dongyu Li ◽  
Xueru Zhang ◽  
Yuxiao Wang ◽  
...  
Keyword(s):  
Focal Spot ◽  
Three Dimensional ◽  
Super Resolution ◽  
Tight Focusing ◽  
Vortex Beams ◽  
Radially Polarized
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