Search results for "Laser beam quality"
showing 10 items of 40 documents
Demonstration of an efficient pumping scheme for a 7.36-nm Ni-like samarium soft x-ray laser
2010
The demonstration of a 7.36 nm Ni-like Sm soft x-ray laser pumped by 36 J of a Nd:glass chirped pulse amplification laser is presented. Double-pulse single-beam non-normal incidence pumping was applied for the efficient soft x-ray laser generation. Here the applied technique included a new single optic focusing geometry for large beam diameters, a single-pass grating compressor traveling-wave tuning capability and an optimized high energy laser double-pulse. This scheme has the potential for even shorter wavelength soft x-ray laser pumping.
Ytterbium-doped fibers for high-power fiber lasers
2021
Ytterbium (Yb) doped optical fibers are widely used in high-power applications and ultrafast lasing since they show adequate power-handling capability and provide desirable beam quality. Yb-doped fibers with large core area can support high power but often act as a multimode fiber and compromise the output beam quality. Hence, it is important to attain a proper balance between the power-handling capability and the beam quality. Yb-doped fibers as a gain medium in pulsed fiber laser systems are prone to nonlinear optical effects due to the presence of high peak power in the ultrashort pulses. Nonlinearity such as self phase modulation (SPM) affects the width and the shape of the pulse, both …
Evaluation of lens absorbed dose with Cone Beam IGRT procedures
2015
The purpose of this work is to evaluate the absorbed dose to the eye lenses due to the cone beam computed tomography (CBCT) system used to accurately position the patient during head-and-neck image guided procedures. The on-board imaging (OBI) systems (v.1.5) of Clinac iX and TrueBeam (Varian) accelerators were used to evaluate the imparted dose to the eye lenses and some additional points of the head. All CBCT scans were acquired with the Standard-Dose Head protocol from Varian. Doses were measured using thermoluminescence dosimeters (TLDs) placed in an anthropomorphic phantom. TLDs were calibrated at the beam quality used to reduce their energy dependence. Average dose to the lens due to …
SU-E-J-69: Evaluation of the Lens Dose On the Cone Beam IGRT Procedures
2014
Purpose: With the establishment of the IGRT as a standard technique, the extra dose that is given to the patients should be taken into account. Furthermore, it has been a recent decrease of the dose threshold in the lens, reduced to 0.5 Gy (ICRP ref 4825-3093-1464 on 21st April, 2011).The purpose of this work was to evaluate the extra dose that the lens is receive due to the Cone-Beam (CBCT) location systems in Head-and-Neck treatments. Methods: The On-Board Imaging (OBI) v 1.5 of the two Varian accelerators, one Clinac iX and one True Beam, were used to obtain the dose that this OBI version give to the lens in the Head-and-Neck location treatments. All CBCT scans were acquired with the Sta…
Beam matching with space charge in energy recovery linacs
2019
Abstract Matching with space charge of an Energy-Recovery Linac (ERL) arc into the subsequent RF structure is essential to preserve beam quality. We show how to match beam envelopes and dispersion along the bends and recirculation arcs of an ERL, including space charge forces, in order to adjust the beam to the parameters of the subsequent RF structure. For a qualitative analysis, we show that one can use a beam matrix approach together with the smooth focusing approximation but with longitudinal–transverse coupling. It is also shown that the space-charge-modified dispersion plays a key role for the adjustment of the momentum compaction R 56 required for both the isochronous and the non-iso…
<title>Optical models used for the study of laser beam</title>
2007
The study of the laser beam is based on optical models, therefore optical models are suited as a tool for study, implement and evaluate the characteristics of an unfocused laser beam. The analysis of the optical models shows the characteristics of pulse and continuous laser beam and the influence over the quality of the industrial process.© (2007) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
High-brilliance double-stage soft x-ray laser pumped by multiple pulses applied in grazing incidence
2014
A new compact scheme for a double-stage seeded x-ray laser is demonstrated. This laser is offering greatly improved beam quality and brilliance making it a useful tool for applications.
Double einzel lens extraction for the JYFL 14 GHz ECR ion source designed with IBSimu
2013
In order to improve the performance of the JYFL 14 GHz electron cyclotron resonance ion source (ECRIS) and initiate low energy beam transport (LEBT) upgrade at the University of Jyvaskyla, Department of Physics (JYFL) accelerator laboratory, a new ion beam extraction system has been designed and installed. The development of the new extraction was performed with the ion optical code IBSimu, making it the first ECRIS extraction designed with the code. The measured performance of the new extraction is in good agreement with the simulations. Compared to the old extraction the new system provides improved beam quality, i.e. lower transverse emittance values and improved structure of beam profil…
Kerr beam self-cleaning in the telecom band
2019
Multimode graded index (GRIN) fibers received a renewed interest in recent years, in particular for the development of new laser sources [1]. In many cases, the use of GRIN fibers is limited by multimodal propagation, leading to a spatially modulated intensity distribution (speckles) at the fiber output. Recent studies have found that quasi-single mode propagation can be recovered in GRIN fibers by the so-called Kerr self-cleaning effect [2]. It consists in the spontaneous recovery of the spatial beam quality, without any frequency shift [2] (as opposed to, e.g., Raman beam self-cleaning [3]). This nonlinear process was only observed so far at laser wavelengths around 1 μm, for peak power l…
Laser beam scattering effects in non-absorbent inhomogenous polymers
2007
Ilie, Mariana Kneip, Jean-Christophe Mattei, Simone Nichici, Alexandru Roze, Claude Girasole, Thierry; In this paper a numerical model for laser beam scattering in the semi-transparent polymers is presented, using a Monte Carlo algorithm and the Mie theory. The algorithm correctly accounts for the independent multiply-scattered light. We describe the algorithm, present a number of important parameters that account in the welding process, and explicitly show how the algorithm can be used to estimate the laser beam intensity both inside the semi-transparent component and at the welding interface and the beam widening. For the model validation an experimental bench test has been realized and s…