29 August 2008 Pump probe experiment for high scattering media diagnostics
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Optical density measurement is a very powerful tool to characterize particle size and physical property of scattering media such as sprays and engine injection. The major difficulty of such a measurement is the tremendous amount of scattered light: for such media, the optical density can be greater than 10. The goal of this work is to develop a new experimental tool, based on femtosecond laser technology in order to isolate (spatially and temporally) a very limited amount of non scattered transmitted light, and to measure the extinction of the media. We collect the transmitted light and we use an optical Kerr gating. This technique is very powerful to determine the time of flight of every photon in the scattering media. By fine-tuning the optical parameter of the setup, we have been able to selectively increase the gating efficiency of the ballistic part vs the diffusive part of the collected light. Furthermore, spectral tunability of amplified femtosecond laser system is straightforward. As a result, it has been possible to measure the extinction spectra of a model diffused media (SiO2 particle in water), and to determine the particle size distribution after inversion method.
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Marie Barthélemy, Marie Barthélemy, Nicolas Rivière, Nicolas Rivière, Laurent Hespel, Laurent Hespel, Thibault Dartigalongue, Thibault Dartigalongue, } "Pump probe experiment for high scattering media diagnostics", Proc. SPIE 7065, Reflection, Scattering, and Diffraction from Surfaces, 70650Z (29 August 2008); doi: 10.1117/12.794774; https://doi.org/10.1117/12.794774


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