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Proceedings Paper

High-efficiency laser-pumping system for magnetic resonance imaging
Author(s): Marziale Milani; Guido Baroni; Lorenzo Ferraro; P. Sozzani; Massimo Adobati; S. Ravetta
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Paper Abstract

Recently the demand for hyperpolarized noble gases is arising to improve NMR spectroscopy resolution for imaging. Hyperpolarization of noble gases is achieved by spin- exchange with alkali metal. atoms that undergo optical pumping by circularly polarized radiation. Optical pumping is usually achieved by high power semiconductor lasers. These sources have a bandwidth very large when compared with the transition bandwidth of the optically active species. This has two serious consequences: (i) the request of high power lasers, (ii) the losses that the unemployed energy delivered to the Rb vapor can provide in the efficiency of the energy transfer. Object of our investigation will be the comparison of two experimental set ups for optical pumping of Rb vapor where pumping is given in one case by a dye laser pumped by a UV nitrogen laser built in our laboratory according to the Blumlein scheme and in the other case by a semiconductor laser. Major elements that will be discussed are (1) the role of stimulated emission of Rb vapor to increase the pumping efficiency, (2) the fate of resonant photons that are emitted during Rb decays, (3) the role of applied magnetic fields in the efficiency of pumping processes.

Paper Details

Date Published: 3 May 2000
PDF: 8 pages
Proc. SPIE 3911, Biomedical Diagnostic, Guidance, and Surgical-Assist Systems II, (3 May 2000); doi: 10.1117/12.384902
Show Author Affiliations
Marziale Milani, Univ. di Milano-Bicocca and INFM (Italy)
Guido Baroni, Univ. di Milano-Bicocca (Italy)
Lorenzo Ferraro, Univ. di Milano-Bicocca (Italy)
P. Sozzani, Univ. di Milano-Bicocca (Italy)
Massimo Adobati, Sapio SpA (Italy)
S. Ravetta, Sapio SpA (Italy)

Published in SPIE Proceedings Vol. 3911:
Biomedical Diagnostic, Guidance, and Surgical-Assist Systems II
Tuan Vo-Dinh; Warren S. Grundfest M.D.; David A. Benaron M.D., Editor(s)

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