title: Measurement of dye diffusion in agar gel by use of low-coherence interferometry.
abstract: We demonstrate low-coherence interferometry for diffusion measurements. We have measured the diffusion coefficient of a phthalocyanine dye in 1.5% agar gel with a two-wavelength interferometer; one wavelength was matched to the absorption peak of the dye at 675 nm, while the other, 805 nm, was not affected by the dye. The diffusion coefficient of the dye was found by fitting a mathematical model for the interferometer signal to the measured low-coherence interferometry amplitude. A 95% confidence interval for the diffusion coefficient was found to be D = (2.5 +/- 0.2) x 10(-10) m2/s. The influence of speckle averaging and experiment time on the determination of the diffusion coefficient has been studied. The presented technique allows in situ characterization of diffusion in semitransparent media.
authors.affiliation: Department of Physics, Norwegian University of Science and Technology, N-7491 Trondheim, Norway. Trude.Storen@phys.ntnu.no
authors.forename: Trude
authors.initials: T
authors.lastname: Støren
authors.forename: Annette
authors.initials: A
authors.lastname: Simonsen
authors.forename: Ole J
authors.initials: OJ
authors.lastname: Løkberg
authors.forename: Tore
authors.initials: T
authors.lastname: Lindmo
authors.forename: Lars O
authors.initials: LO
authors.lastname: Svaasand
authors.forename: Arne
authors.initials: A
authors.lastname: Røyset
mesh_terms: D000362:Agar; D004396:Coloring Agents; D004058:Diffusion; D005782:Gels; D007368:Interferometry; D008962:Models, Theoretical
chemical_list: D004396:Coloring Agents; D005782:Gels; D000362:Agar