Results 261 to 270 of about 239,845 (311)

Beam quality specification for photon beam dosimetry

Medical Physics, 1993
It 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, 2012
Zernike 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, Lei, Huang, Mali, Gong, Liu, Qiang, Ping, Yan, Haitao, Zhang   +5 more
openaire   +2 more sources

The beam quality of a truncated Gaussian beam with aberrations

Laser Physics Letters, 2013
We 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, Mali Gong, Lei Huang, Qiang Liu, Ping Yan, Haitao Zhang, Tenghao Li   +6 more
openaire   +1 more source

Effect of holes and vortices on beam quality

Journal of the Optical Society of America A, 2000
The effect of a vortex on the invariant quality factors of a light beam is studied. It is shown that a vortex degrades beam quality. The beam intensity at the eye of the vortex necessarily vanishes, creating a hole in the intensity distribution. The degradation in the beam quality is shown to be due partly to the vortex phase and partly to the hole ...
S, Ramee, R, Simon
openaire   +2 more sources

Quality of paraxial electromagnetic beams

Applied Optics, 2006
The 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

High beam-quality tea lasers

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

Quality improvement of partially polarized beams

Applied Optics, 2001
Improvement 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, R, Martínez-Herrero, P M, Mejías   +2 more
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Comment on “Quality of paraxial electromagnetic beams”

Applied Optics, 2008
We 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

Beam quality measurements using digitized laser beam images

Applied Optics, 1989
A method is described for measuring various laser beam characteristics with modest experimental complexity by digital processing of the near and far field images. Gaussian spot sizes, peak intensities, and spatial distributions of the images are easily found. Far field beam focusability is determined by computationally applying apertures of circular or
M D, Duncan, R, Mahon
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Effect of turbulence on the beam quality of apertured partially coherent beams

Journal of the Optical Society of America A, 2008
The effects of turbulence on the beam quality of apertured partially coherent beams have been studied both analytically and numerically. Taking the Gaussian Schell-model (GSM) beam as a typical example of partially coherent beams, closed-form expressions for the average intensity, mean-squared beam width, power in the bucket, beta parameter, and Strehl
Xiaoling, Ji, Guangming, Ji
openaire   +2 more sources