Visualization of Temperature Profiles in a-Si Crystallized in the Explosive Mode by Ow Laser.

1982 ◽  
Vol 13 ◽  
Author(s):  
Michel Rivier ◽  
Andras Cserhati ◽  
George Goetz
Keyword(s):  
Laser Beam ◽  
Experimental Method ◽  
Intensity Distribution ◽  
Difficult Problem ◽  
Laser Beams ◽  
Scanning Laser ◽  
Multilayer Structures ◽  
Complex Geometries ◽  
Temperature Profiles ◽  
Spatial Intensity Distribution

ABSTRACTWe present an experimental method, based on the isothermal nature of the boundaries of explosively crystallized silicon, to display instantaneous isotherms produced by fast scanning laser beams. This method is especially useful for the case of multilayer structures or complex geometries, where thermal profiles simulation is a difficult problem. We can also obtain directly a measure of the spatial intensity distribution in the laser beam.

Spatial intensity distribution of the radiative return from scattering media irradiated by a cw laser beam

2017 ◽  
Author(s):  
Ljuan L. Gurdev ◽  
Tanja N. Dreischuh ◽  
Orlin I. Vankov ◽  
Eleonora N. Toncheva ◽  
Lachezar A. Avramov ◽  
...  
Keyword(s):  
Laser Beam ◽  
Intensity Distribution ◽  
Scattering Media ◽  
Spatial Intensity Distribution ◽  
Spatial Intensity ◽  
Cw Laser ◽  
Radiative Return

scholarly journals A study on the effects and visibility of low-order aberrations on laser beams with orbital angular momentum

2019 ◽  
Vol 125 (11) ◽  
Author(s):  
Jonas B. Ohland ◽  
Udo Eisenbarth ◽  
Markus Roth ◽  
Vincent Bagnoud
Keyword(s):  
Angular Momentum ◽  
Laser Beam ◽  
Orbital Angular Momentum ◽  
Intensity Distribution ◽  
Laser Beams ◽  
Far Field ◽  
Wavefront Aberrations ◽  
Tolerance Criteria ◽  
Selection Of ◽  
Low Order

Abstract Laguerre–Gaussian-like laser beams have been proposed for driving experiments with high-intensity lasers. They carry orbital angular momentum and exhibit a ring-shaped intensity distribution in the far field which make them particularly attractive for various applications. We show experimentally and numerically that this donut-like shape is extremely sensitive to off-axis wavefront deformations. To support our claim, we generate a Laguerre–Gaussian-like laser beam and apply a selection of common low-order wavefront aberrations. We investigate the visibility of those wavefront deformations in the far field. Under use of established tolerance criteria, we determine the thresholds for the applied aberration and compare the findings with simulations for verification.

Binary phase zone-plate arrays for laser-beam spatial-intensity distribution conversion

1995 ◽  
Vol 34 (20) ◽  
pp. 4025 ◽  
Author(s):  
T. H. Bett ◽  
C. N. Danson ◽  
P. Jinks ◽  
D. A. Pepler ◽  
I. N. Ross ◽  
...  
Keyword(s):  
Laser Beam ◽  
Intensity Distribution ◽  
Zone Plate ◽  
Phase Zone ◽  
Binary Phase ◽  
Spatial Intensity Distribution ◽  
Spatial Intensity

scholarly journals Влияние ограниченной апертуры излучателя на характеристики ширины и угла расходимости лазерного пучка

2019 ◽  
Vol 127 (11) ◽  
pp. 851
Author(s):  
А.М. Райцин
Keyword(s):  
Laser Beam ◽  
Cross Section ◽  
Intensity Distribution ◽  
Necessary Conditions ◽  
Spatial Moments ◽  
Spatial Intensity Distribution ◽  
Spatial Intensity ◽  
The Cross

The necessary conditions for the correct measurement of the width and angle of divergence of the laser beam are determined taking into account the finite dimensions of the aperture of the emitter by a method based on the determination of initial spatial moments. It is shown that in this case stringent conditions are imposed on the shape of the spatial intensity distribution in the cross section of the laser beam, which were not taken into account in the corresponding developed standards.

scholarly journals Laser beam welding setup for the coaxial combination of two laser beams to vary the intensity distribution

2022 ◽  
Author(s):  
M. Möbus ◽  
P. Woizeschke
Keyword(s):  
Laser Beam ◽  
Penetration Depth ◽  
Intensity Distribution ◽  
Laser Beam Welding ◽  
Sample Surface ◽  
Laser Beams ◽  
Deep Penetration ◽  
Focal Position ◽  
Laser Systems ◽  
Laser Sources

AbstractDeep-penetration laser beam welding is highly dynamic and affected by many parameters. Several investigations using differently sized laser spots, spot-in-spot laser systems, and multi-focus optics show that the intensity distribution is one of the most influential parameters; however, the targeted lateral and axial intensity design remains a major challenge. Therefore, a laser processing optic has been developed that coaxially combines two separate laser sources/beams with different beam characteristics and a measuring beam for optical coherence tomography (OCT). In comparison to current commercial spot-in-spot laser systems, this setup not only makes it possible to independently vary the powers of the two laser beams but also their focal planes, thus facilitating the investigation into the influence of specific energy densities along the beam axis. First investigations show that the weld penetration depth increases with increasing intensities in deeper focal positions until the reduced intensity at the sample surface, due to the deep focal position, is no longer sufficient to form a stable keyhole, causing the penetration depth to drop sharply.

Correct measurement methodology spatial-energy characteristics of laser beams

Metrologiya ◽  
2021 ◽  
pp. 4-19
Author(s):  
A. M. Raitsmm ◽  
M. V. Ulanovskii
Keyword(s):  
Laser Beam ◽  
Dynamic Range ◽  
Radiation Detectors ◽  
Test Methods ◽  
National Standard ◽  
Laser Beams ◽  
Energy Characteristics ◽  
Uniformity Of Measurements ◽  
Spatial Intensity Distribution ◽  
Array Detectors

A methodology for correct measurements of the spatial and energy characteristics of a laser beam is considered, based on the determination of the initial moments of the spatial intensity distribution in the beam cross section. The classification of radiation fields participating in the measuring process is given: emitted, measured and measured. It is shown that ISO 11146:2005 “Lasers and laser-related equipment. Test methods for laser beam widths, divergence angles and beam propagation ratios, Part 1-3” for measuring the spatial and energy characteristics of laser beams leads to incorrect measurements. This is due to the fact that the recommendations for the application of ISO 11146:2005 do not take into account the dynamic range of the used matrix radiation detectors, and the characteristics of the emitted field of interest to the user turn out to be diverging, which violates the uniformity of measurements. Moreover, the conditions ensuring the convergence of the results are practically impracticable. To solve these problems, it is proposed to establish and regulate the lower level of the dynamic range of measurements of the intensity of the used matrix receivers and to consider the spatial and energy characteristics of the emitted field of interest to the user, depending on the set value of the lower level. It is shown that measurements with this methodology become correct and make it possible to compare the characteristics of laser beams obtained by different array detectors. Formulas are given that take into account the effect of the lower level of the dynamic range of the matrix radiation detectors on the measurement result. These formulas should be recommended for inclusion in the updated edition of the national standard GOST R ISO 11146-2008 “Lasers and laser installations (systems). Methods for measuring widths, divergence angles and propagation coefficients of laser beams. Parts 1-3”.

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