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Beam Direction (beam + direction)

Distribution by Scientific Domains

Chemistry	50%

Selected Abstracts

TLM modelling of microstrip patch antenna on ferrite substrate

INTERNATIONAL JOURNAL OF RF AND MICROWAVE COMPUTER-AIDED ENGINEERING, Issue 3 2001
M. I. Sobhy
Abstract A new TLM modelling method has been developed for patch antennas on magnetized ferrite substrate. The antenna has magnetically controllable resonance frequency and beam direction. The anisotropic permeability tensor of ferrite is modelled by state equations derived from the Polder tensor. Simulation results agree with measurement. © 2001 John Wiley & Sons, Inc. Int J RF and Microwave CAE 11: 131,139, 2001. [source]

Determination of directionally dependent structural and microstructural information using high-energy X-ray diffraction

JOURNAL OF APPLIED CRYSTALLOGRAPHY, Issue 6 2008
J. E. Daniels
High-energy synchrotron X-ray diffraction using a monochromatic beam and large area detector offers a unique method for the study of directionally dependent sample information. The very short wavelengths and subsequent low scattering angles mean that scattering vectors at all angles approximately perpendicular to the beam direction are sampled simultaneously. Here a method is proposed and demonstrated in which the magnitude and directions of structural and microstructural changes can be determined with higher resolution than was possible with previously used techniques. The method takes advantage of parametric refinements over multiple data sets using the profile fitting package TOPAS. Examples of the technique applied to the study of strains in multiphase zirconium alloys and microstructural texture in ferroelastic/ferroelectric ceramics are given. The angular precision in lattice strain for a diffraction image with good statistics is found to be below 0.1°. [source]

Targeting of the retinal pigment epithelium (RPE) by means of a rapidly scanned continuous wave (CW) laser beam

LASERS IN SURGERY AND MEDICINE, Issue 4 2003
Ralf Brinkmann
Abstract Background and Objectives Selective treatment of the retinal pigment epithelium (RPE) by repetitively applying green ,s-laser pulses is a new method for retinal diseases associated with a degradation of the RPE, which spares the neural retina. We investigated an alternative approach to realize repetitive ,s-laser exposure by rapidly scanning a continuous wave (CW)-laser beam across the RPE. Study Design/Materials and Methods An Ar+ laser beam (514 nm) with a diameter of 18.75 ,m was repetitively scanned across porcine RPE samples in vitro providing an irradiation time of 1.6 ,s per point on the central scan axis. RPE cell damage was investigated by means of the fluorescence viability assay Calcein-AM. Results The ED50 cell damage is 305 mJ/cm2 when applying 10 scans with a repetition rate of 500 Hz. The threshold decreases with the number of scans, a saturation was found at 135 mJ/cm2 with more than 500 exposures applied. The depth of focus in beam direction is 350 ,m, defined by an increase of the threshold radiant exposure by 20%. Conclusions Targeting of pigmented cells with high local resolution has been proved with a laser-scanning device. Looking ahead selective RPE-treatment, the adaptation of a laser-scanning device on a slit-lamp or into a modified retina angiograph seems to be an attractive alternative to the pulsed ,s laser device. Lasers Surg. Med. 32:252,264, 2003. © 2003 Wiley-Liss, Inc. [source]

A general expression of the polarization factor for multi-diffraction processes

ACTA CRYSTALLOGRAPHICA SECTION A, Issue 3 2010
Kiyoaki Tanaka
A general expression of the polarization factor of multi-diffracted beams is formulated. By assigning the diffracted beam direction of each diffraction process as the y axis of a Cartesian coordinate system, the polarization factor of multi-diffraction processes can be easily calculated for polarized and unpolarized beams without being limited by the number of diffraction processes. The method can be applied to processes with more than three scattering events such as multiple diffraction and extinction. [source]