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Vila M.,Complutense University of Madrid | Vila M.,CIBER ISCIII | Izquierdo-Barba I.,Complutense University of Madrid | Izquierdo-Barba I.,CIBER ISCIII | And 3 more authors.
Journal of Sol-Gel Science and Technology | Year: 2011

Bimodal porous nanocrystalline hydroxyapatite (HA) coatings with pore sizes in the range of meso/macro meter scale have been deposited onto Ti6Al4V substrates by sol-gel method using nonionic surfactant as porous former agent. By increasing the molar ratio between phosphorous source and surfactant to 0.006, a very homogeneous bimodal distribution of pores in the range of 4.5-10 nm and 0.2 μm have been obtained. © 2010 Springer Science+Business Media, LLC.

Sofikitis D.,Foundation for Research and Technology Hellas | Sofikitis D.,University of Crete | Stamataki K.,Foundation for Research and Technology Hellas | Stamataki K.,University of Crete | And 6 more authors.
Optics Letters | Year: 2013

We demonstrate a method to increase the sensitivity of the s-p phase shift under total internal reflection (TIR) for optical sensing. This is achieved by the introduction of two simple dielectric layers to the TIR surface of a fused silica prism. The enhanced sensitivity is demonstrated using evanescent-wave cavity-ring-down-ellipsometry by measuring the refractive index of liquid mixtures and by studying the adsorption of polymers to the TIR surface of the fused silica prism. © 2013 Optical Society of America.

Stehle J.-L.,Sopralab | Samartzis P.C.,Foundation for Research and Technology Hellas | Stamataki K.,Foundation for Research and Technology Hellas | Stamataki K.,University of Crete | And 7 more authors.
Thin Solid Films | Year: 2014

Spectroscopic ellipsometry is an established technique, particularly useful for thickness measurements of thin films. It measures polarization rotation after a single reflection of a beam of light on the measured substrate at a given incidence angle. In this paper, we report the development of multi-pass spectroscopic ellipsometry where the light beam reflects multiple times on the sample. We have investigated both theoretically and experimentally the effect of sample reflectivity, number of reflections (passes), angles of incidence and detector dynamic range on ellipsometric observables tanΨ and cosΔ. The multiple pass approach provides increased sensitivity to small changes in Ψ and Δ, opening the way for single measurement determination of optical thickness T, refractive index n and absorption coefficient k of thin films, a significant improvement over the existing techniques. Based on our results, we discuss the strengths, the weaknesses and possible applications of this technique. © 2013 Elsevier B.V.

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