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Proceedings Paper

Laser-induced fluorescence studies on collagen, cholesterol, and chlorophyll a
Author(s): Mihail-Lucian Pascu; N. Moise; S. Hogiu
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Paper Abstract

Results on laser induced fluorescence (LIF) properties of collagen, cholesterol, and chlorophyll a (chl a) are reported, when excited at 337.1 nm. The collagen and cholesterol fluorescence was studied in connection with atherosclerotic plaques diagnostics and/or removal within the cardiovascular system. The fluorescence signal excitation and collection were made using optical fibers, for liquid samples at concentrations between 0.1 mg/ml and 5.0 mg/ml for both collagen and cholesterol, their fluorescence lifetime being 5 nsec and 6 nsec, respectively. CHl a LIF concerned the stimulated emission of radiation considering the pigment as laser active medium. Chl a concentrations varied, in different solvents between 5 multiplied by 10-3 M/l and 10-5 M/l. For chl a at 0.62 mM/l and pumping photon densities higher than 5 multiplied by 1016 photons/cm2 and pulse, fluorescence linewidth narrowing from 28 nm to 5 nm in ethanol and from 25 nm to 4 nm in DMSO were obtained. Lasing maxima at 672 nm in acetone, 674 nm in ethanol and 678 nm in DMSO were observed. At lasing conditions for chl a in DMSO (1mM/l) the measured fluorescence lifetime was 2 nsec instead of 5 nsec for normal fluorescence. The results on chl a stimulated emission show a lower lasing threshold at 1016 photons/cm2 and pulse, than previously reported, if DMSO solvent is used.

Paper Details

Date Published: 27 December 1995
PDF: 5 pages
Proc. SPIE 2627, Optical Biopsies, (27 December 1995); doi: 10.1117/12.228895
Show Author Affiliations
Mihail-Lucian Pascu, Institute of Physics and Technology of Radiation Devices (Romania)
N. Moise, Institute of Physics and Technology of Radiation Devices (Romania)
S. Hogiu, Institute of Physics and Technology of Radiation Devices (Romania)

Published in SPIE Proceedings Vol. 2627:
Optical Biopsies
Rinaldo Cubeddu; Serge R. Mordon; Katarina Svanberg M.D., Editor(s)

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