We study theoretically accessible optical vortex rings and their topological transformations in superpositions of elliptic and astigmatic Gaussian beams with a plane wave. We demonstrate the birth and death of vortex rings at isolated points on and off the optical axis and their pairwise and higher-order three- and four-ring reconnections.
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http://dx.doi.org/10.1364/OL.515817 | DOI Listing |
Sensors (Basel)
January 2025
InViLab, Department of Electromechanical Engineering, University of Antwerp, Groenenborgerlaan 171, 2020 Antwerp, Belgium.
Laser-based systems, essential in diverse applications, demand accurate geometric calibration to ensure precise performance. The calibration process of the system requires establishing a reliable relationship between input parameters and the corresponding 3D description of the outgoing laser beams. The quality of the calibration depends on the quality of the dataset of measured laser lines.
View Article and Find Full Text PDFBiomed Phys Eng Express
January 2025
Department of Medical Physics, Osaka Heavy Ion Therapy Center, Otemae, Chuo-ku, Osaka, Osaka, 5400008, JAPAN.
Objective Applying carbon ion beams, which have high linear energy transfer and low scatter within the human body, to Spatially Fractionated Radiation Therapy (SFRT) could benefit the treatment of deep-seated or radioresistant tumors. This study aims to simulate the dose distributions of spatially fractionated beams (SFB) to accurately determine the delivered dose and model the cell survival rate following SFB irradiation. Approach Dose distributions of carbon ion beams are calculated using the Triple Gaussian Model.
View Article and Find Full Text PDFWe derive the Goos-Hänchen (GH) and Imbert-Fedorov (IF) shifts of random electromagnetic beams with arbitrary state and degree of polarization and spatial coherence. Further, we demonstrate the general formalism by calculating analytic expressions for the GH and IF shifts of an electromagnetic Gaussian Schell-model (EGSM) beam and show that the GH shifts may exist irrespective of the degree and state of polarization of the beam, while the IF shifts vanish when the beam is either s or p polarized or completely unpolarized. In addition, the spatial coherence width of the EGSM beam is found to influence only the angular GH and IF shifts.
View Article and Find Full Text PDFInt J Part Ther
March 2025
Institute of Medical Physics and Radiation Protection, University of Applied Sciences, Giessen, Germany.
Purpose: The spot size of scanned particle beams is of crucial importance for the correct dose delivery and, therefore, plays a significant role in the quality assurance (QA) of pencil beam scanning ion beam therapy.
Materials And Methods: This study compares 5 detector types-radiochromic film, ionization chamber (IC) array, flat panel detector, multiwire chamber, and IC-for measuring the spot size of proton and carbon ion beams.
Results: Variations of up to 30% were found between detectors, underscoring the impact of detector choice on QA outcomes.
Biomed Phys Eng Express
January 2025
Department of Medical Physics, Osaka Heavy Ion Therapy Center, Otemae, Chuo-ku, Osaka, Osaka, 5400008, JAPAN.
Objective Applying carbon ion beams, which have high linear energy transfer and low scatter within the human body, to Spatially Fractionated Radiation Therapy (SFRT) could benefit the treatment of deep-seated or radioresistant tumors. This study aims to simulate the dose distributions of spatially fractionated beams (SFB) to accurately determine the delivered dose and model the cell survival rate following SFB irradiation. Approach Dose distributions of carbon ion beams are calculated using the Triple Gaussian Model.
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