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Design and performance of a new ophthalmic instrument for dynamic light-scattering measurements in the human eye (1996)

Rovati, L. ; Fankhauser, F. ; Ricka, J.

[S.l.] : American Institute of Physics (AIP)

Review of Scientific Instruments 67 (1996), S. 2615-2620

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ISSN: 1089-7623

Source: AIP Digital Archive

Topics: Physics , Electrical Engineering, Measurement and Control Technology

Notes: A new optical instrument for in vivo dynamic light-scattering measurements in the human eye is described. The instrument is based on the well-known dynamic light-scattering technique. Results can be obtained from the anterior as well as the posterior segment with high spatial resolution and sensitivity. This instrument allows, to our knowledge for the first time, in vivo measurements of dynamic light scattering to be performed in the vitreous. Interesting performance is obtained using single-mode optical fibers to guide the excitation and the scattered light resulting in a modular, compact system with high-beam quality and electrical insulation of the patient. The instrument demonstrates good safety characteristics (the optical power impinging the patient's eye is 36 times below the maximum laser power at the cornea, recommended for intrapupil exposure by ANSI standard). To demonstrate the possible clinical use of this technique, in vivo measurements were made and the results compared with the known eye pathologies. © 1996 American Institute of Physics.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1063/1.1147224

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Single-mode DLS: colloids in opaque porous media (1997)

Rička, J. ; Flammer, I. ; Leutz, W.

Springer

Colloid & polymer science 104 (1997), S. 49-58

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ISSN: 1435-1536

Keywords: Single-mode dynamic light scattering ; opaque porous media ; diffusion ; convection ; tortuosity

Source: Springer Online Journal Archives 1860-2000

Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics

Notes: Abstract Single-mode fiber optical receivers have become the instrumentation standard for Dynamic Light Scattering (DLS). In a regular homodyne experiment one values their superb signal-to-noise ratio as well as the simplicity of the optical setup. Moreover, mode-selective DLS enables the researcher to tackle seemingly hopeless experimental problems, such as colloidal motions inside an opaque porous medium consisting of a water filled packing of small glass grains. The particles to be measured are completely masked by strong diffuse scattering in the porous matrix. Nevertheless, mode-selective DLS makes it possible not only to detect the motions of the colloids within the pores but also to determine their diffusion coefficient and, simultaneously, their average convective speed. We outline the theoretical background of these measurements and present data on diffusion and convection of latex particles in dense packings of glass-beads in a Chromatographic column. Our technique allows an accurate determination of the tortuosity of the interstitial flow.