Dependence of the stability and the beam quality on the distance between two rods in a double laser-head resonator

2002 ◽  
Vol 201 (4-6) ◽  
pp. 381-389 ◽  
Author(s):  
Hyun Su Kim ◽  
Sungman Lee ◽  
Do-Kyeong Ko ◽  
Byung Heon Cha
Keyword(s):  
Beam Quality ◽  
Laser Head ◽  
The Stability

The Software Development of Double-Beam Centroid Distance Measurement System in Laser Cladding Forming Process

2011 ◽  
Vol 464 ◽  
pp. 524-527
Author(s):  
Cheng Feng Sun ◽  
Shi Hong Shi ◽  
Ge Yan Fu ◽  
Chun Sheng Li
Keyword(s):  
Laser Cladding ◽  
Molten Pool ◽  
Forming Process ◽  
Development Platform ◽  
Laser Head ◽  
Centroid Distance ◽  
Double Beam ◽  
Spot Image ◽  
The Stability ◽  
Effect Of Light

In the high-piled up process of laser cladding rapid forming , the distance between aser molten pool center and flour will increase along with the cladding layer ,which will cause the effect of light powder coupling getting worse, even directly lead to failure. The article proposed characteristics of the double-spot ,formed by molten pool and reflection of laser surface;used VC++ 6.0 as the development platform of image processing to calculate two spot centroid distance by dealing two spot image with the process of gray processing, Gaussian smoothing, binary threshold segmentation, area centroid calculation, the centroid coordinate distance calculation.At the same time , controlling laser head Z to move in accordance with the value increment,to increase the stability of forming process and forming quality.

scholarly journals Design and Development of the Folded 4-Mirror Resonators for Diode End-pumped Solid-State Cr:LiSAF Laser

2016 ◽  
Vol 24 (3S2) ◽  
pp. 109-120
Author(s):  
Nguyen Van Hao ◽  
Pham Van Duong ◽  
Pham Hong Minh ◽  
Do Quoc Khanh ◽  
Antonio Agnesi
Keyword(s):  
Solid State ◽  
Comparative Studies ◽  
Oblique Incidence ◽  
Laser Crystal ◽  
Beam Quality ◽  
Design And Development ◽  
Stability Regions ◽  
Beam Parameters ◽  
The Stability ◽  
Sensitive Parameters

We present the design and development of folded four-mirror resonators for diode end-pumped solid-state Cr:LiSAF lasers. The astigmatic effects due to the Brewster-cut laser crystal and two curved mirrors used at oblique incidence were taken into consideration. The obtained results showed the stability regions of resonator, the beam parameters in the resonator and within the laser crystal as well as other sensitive parameters and their variation ranges. Furthermore, the designed folded four-mirror resonators for diode end-pumped Cr:LiSAF laser were experimentally evaluated. The CW Cr:LiSAF laser characteristics in threshold, efficiency and beam quality as well as comparative studies are presented.

scholarly journals Virtual Diagnostic Suite for Electron Beam Prediction and Control at FACET-II

2021 ◽  
Author(s):  
Claudio Emma ◽  
Auralee Edelen ◽  
Adi Hanuk ◽  
Brendan O'Shea ◽  
Alexander Scheinker
Keyword(s):  
Beam Quality ◽  
Simulation Data ◽  
Transverse Beam ◽  
Spectral Reconstruction ◽  
Edge Radiation ◽  
Measurement Results ◽  
Prediction And Control ◽  
The Stability ◽  
And Control ◽  
Non Destructive

We discuss the implementation of a suite of virtual diagnostics at the FACET-II facility currently under commissioning at SLAC National Accelerator Laboratory. The diagnostics will be used for prediction of the longitudinal phase space along the linac, spectral reconstruction of the bunch profile and non-destructive inference of transverse beam quality (emittance) using edge radiation at the injector dogleg and bunch compressor locations. These measurements will be folded in to adaptive feedbacks and ML-based reinforcement learning controls to improve the stability and optimize the performance of the machine for different experimental configurations. In this paper we describe each of these diagnostics with expected measurement results based on simulation data and discuss progress towards implementation in regular operations.

scholarly journals Development and prospect of high-power doped fibers

2018 ◽  
Vol 6 ◽  
Author(s):  
Yibo Wang ◽  
Gui Chen ◽  
Jinyan Li
Keyword(s):  
Output Power ◽  
High Power ◽  
Fiber Lasers ◽  
Beam Quality ◽  
Research Work ◽  
Excited State Absorption ◽  
Single Mode ◽  
Energy Structure ◽  
Doped Fibers ◽  
The Stability

Ytterbium-doped fibers have become the optimum gain media of high-power fiber lasers thanks to a simple energy structure, which strongly reduces the excited state absorption, and a low quantum defect and a high optic–optic conversion efficiency, which means the low thermal load. In this paper, we take a review of the current state of the art in terms of $\text{Yb}^{3+}$ doped fibers for high-power fiber lasers, including the development of the fabrication techniques. The research work to overcome the challenges for $\text{Yb}^{3+}$ doped fibers, which affect the stability of output power and beam quality, will be demonstrated. Direction of further research is presented and the goal is to look for a fiber design, to boost single fiber output power, stabilize the laser power and support robust single-mode operation.

scholarly journals Virtual Diagnostic Suite for Electron Beam Prediction and Control at FACET-II

Information ◽  
2021 ◽  
Vol 12 (2) ◽  
pp. 61
Author(s):  
Claudio Emma ◽  
Auralee Edelen ◽  
Adi Hanuka ◽  
Brendan O’Shea ◽  
Alexander Scheinker
Keyword(s):  
Beam Quality ◽  
Simulation Data ◽  
Transverse Beam ◽  
Spectral Reconstruction ◽  
Edge Radiation ◽  
Measurement Results ◽  
Prediction And Control ◽  
The Stability ◽  
And Control ◽  
Non Destructive

We discuss the implementation of a suite of virtual diagnostics at the FACET-II facility currently under commissioning at SLAC National Accelerator Laboratory. The diagnostics will be used for the prediction of the longitudinal phase space along the linac, spectral reconstruction of the bunch profile, and non-destructive inference of transverse beam quality (emittance) while using edge radiation at the injector dogleg and bunch compressor locations. These measurements will be folded into adaptive feedbacks and Machine Learning (ML)-based reinforcement learning controls to improve the stability and optimize the performance of the machine for different experimental configurations. In this paper we describe each of these diagnostics with expected measurement results that are based on simulation data and discuss progress towards implementation in regular operations.

Open discussion

1982 ◽  
Vol 99 ◽  
pp. 605-613
Author(s):  
P. S. Conti
Keyword(s):  
Buenos Aires ◽  
Large Mass ◽  
List Type ◽  
Common Phenomenon ◽  
Open Discussion ◽  
The Stability ◽  
Ring Nebulae

Conti: One of the main conclusions of the Wolf-Rayet symposium in Buenos Aires was that Wolf-Rayet stars are evolutionary products of massive objects. Some questions:–Do hot helium-rich stars, that are not Wolf-Rayet stars, exist?–What about the stability of helium rich stars of large mass? We know a helium rich star of ∼40 MO. Has the stability something to do with the wind?–Ring nebulae and bubbles : this seems to be a much more common phenomenon than we thought of some years age.–What is the origin of the subtypes? This is important to find a possible matching of scenarios to subtypes.

Symmetric Multistep Methods Revisited: II. Numerical Experiments

1999 ◽  
Vol 173 ◽  
pp. 309-314 ◽  
Author(s):  
T. Fukushima
Keyword(s):  
Multistep Methods ◽  
Computational Time ◽  
Integration Time ◽  
Implicit Methods ◽  
Symmetric Methods ◽  
Celestial Bodies ◽  
The Stability ◽  
Predictor Corrector ◽  
Symmetric Multistep Methods ◽  
Integration Errors

AbstractBy using the stability condition and general formulas developed by Fukushima (1998 = Paper I) we discovered that, just as in the case of the explicit symmetric multistep methods (Quinlan and Tremaine, 1990), when integrating orbital motions of celestial bodies, the implicit symmetric multistep methods used in the predictor-corrector manner lead to integration errors in position which grow linearly with the integration time if the stepsizes adopted are sufficiently small and if the number of corrections is sufficiently large, say two or three. We confirmed also that the symmetric methods (explicit or implicit) would produce the stepsize-dependent instabilities/resonances, which was discovered by A. Toomre in 1991 and confirmed by G.D. Quinlan for some high order explicit methods. Although the implicit methods require twice or more computational time for the same stepsize than the explicit symmetric ones do, they seem to be preferable since they reduce these undesirable features significantly.

Uniformity of Magnification from Different Electron Microscopes

1967 ◽  
Vol 25 ◽  
pp. 32-33
Author(s):  
Godfrey C. Hoskins ◽  
V. Williams ◽  
V. Allison
Keyword(s):  
Diffraction Grating ◽  
The Other ◽  
Carbon Replica ◽  
Electron Microscopes ◽  
The Stability

The method demonstrated is an adaptation of a proven procedure for accurately determining the magnification of light photomicrographs. Because of the stability of modern electrical lenses, the method is shown to be directly applicable for providing precise reproducibility of magnification in various models of electron microscopes.A readily recognizable area of a carbon replica of a crossed-line diffraction grating is used as a standard. The same area of the standard was photographed in Phillips EM 200, Hitachi HU-11B2, and RCA EMU 3F electron microscopes at taps representative of the range of magnification of each. Negatives from one microscope were selected as guides and printed at convenient magnifications; then negatives from each of the other microscopes were projected to register with these prints. By deferring measurement to the print rather than comparing negatives, correspondence of magnification of the specimen in the three microscopes could be brought to within 2%.

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