Results 251 to 260 of about 7,941,196 (306)
Some of the next articles are maybe not open access.
Beam quality measure for vector beams
Optics Letters, 2016Vector beams have found a myriad of applications, from laser materials processing to microscopy, and are now easily produced in the laboratory. They are usually differentiated from scalar beams by qualitative measures, for example, visual inspection of beam profiles after a rotating polarizer.
Bienvenu, Ndagano +4 more
openaire +2 more sources
Beam quality specification for photon beam dosimetry
Medical Physics, 1993It is argued that %dd(10), the percentage depth dose at 10 cm in a 10×10 cm2 photon beam at a SSD of 100 cm, is a better beam quality specifier for radiotherapy beams than the commonly used values of or nominal accelerating potential (NAP). For radiation dosimetry purposes, is not an ideal beam quality specifier because (i) stopping‐power ratios for ...
Kosunen, A., Rogers, D. W.O.
openaire +3 more sources
Method to evaluate beam quality of Gaussian beams with aberrations
Applied Optics, 2012Zernike polynomials are commonly used to describe the aberration of light beams, and the beam quality of Gaussian beams with aberrations can be deduced when the order of Zernike polynomials is limited. In this paper, Hermite polynomials are utilized to reconstruct the aberrations of Gaussian beams.
Yuntao, Qiu +5 more
openaire +2 more sources
The beam quality of a truncated Gaussian beam with aberrations
Laser Physics Letters, 2013We present a method for the calculation of the beam quality factor of an aberrated laser beam. The closed-form equations are proved, and it is shown that the beam quality factor of an aberrated Gaussian beam depends directly on the Hermite coefficient of the wavefront, as well as the truncation ratio.
Yuntao Qiu +6 more
openaire +1 more source
Optics Communications, 1976
Abstract The homogeneity of various types of self-sustained TEA laser discharges in CO 2 -N 2 -He mixtures has been investigated. It is shown that the double Rogowski uv-preionized configuration is the most suitable for the attainment of high quality laser emission. In such systems refractive index variations are delayed for the longest period.
Dufour, M., Egger, H., Seelig, W.
openaire +2 more sources
Abstract The homogeneity of various types of self-sustained TEA laser discharges in CO 2 -N 2 -He mixtures has been investigated. It is shown that the double Rogowski uv-preionized configuration is the most suitable for the attainment of high quality laser emission. In such systems refractive index variations are delayed for the longest period.
Dufour, M., Egger, H., Seelig, W.
openaire +2 more sources
Quality of paraxial electromagnetic beams
Applied Optics, 2006The full wave theory of focused waves is developed and the radiation intensity distribution is determined. In the appropriate limit, the full wave theory correctly reproduces the paraxial beams. The limitations of paraxial beam theories are discussed. The method of treatment of full waves is presented with reference to the scalar Bessel-Gauss beam and ...
openaire +2 more sources
1983
There are a variety of mechanisms which change the refractive index of the medium in which the pulse propagates. These changes in the refractive index may lead to a distortion of the wave-front of the pulse, thereby increasing the energy losses of the beam and deteriorating its focusibility.
Günter Brederlow +2 more
openaire +1 more source
There are a variety of mechanisms which change the refractive index of the medium in which the pulse propagates. These changes in the refractive index may lead to a distortion of the wave-front of the pulse, thereby increasing the energy losses of the beam and deteriorating its focusibility.
Günter Brederlow +2 more
openaire +1 more source
Quality improvement of partially polarized beams
Applied Optics, 2001Improvement of the beam-quality parameter of partially polarized beams is investigated. We focus on the use of a Mach-Zehnder-type interferometric arrangement with crossed polarizers. The analysis has been carried out within the framework of the intensity moment formalism. Conditions are given under which the beam-quality parameter is optimized.
J M, Movilla +2 more
openaire +2 more sources
Comment on “Quality of paraxial electromagnetic beams”
Applied Optics, 2008We comment on a recent paper by Seshadri [Appl. Opt.45, 5335 (2006)]APOPAI0003-693510.1364/AO.45.005335. In the cited work the author utilized the so-named Felsen method in order to derive the full wave expression of a scalar Bessel-Gauss field, propagating in free space, originated from an assigned input distribution on the source plane z = 0.
Omar, El Gawhary, Sergio, Severini
openaire +2 more sources
Experimental validation of beam quality correction factors for proton beams
Physics in Medicine and Biology, 2015This paper presents a method to experimentally validate the beam quality correction factors (kQ) tabulated in IAEA TRS-398 for proton beams and to determine the kQ of non-tabulated ionization chambers (based on the already tabulated values). The method is based exclusively on ionometry and it consists in comparing the reading of two ionization chambers
Gomà, Carles +3 more
openaire +4 more sources