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Proceedings Paper

Realization of a new sensor for a real-time local measurement of tissue optical coefficients
Author(s): Dominique Ettori; Eric Tinet; Tuan Nguyen Tien; Franck Revel; Jean-Michel Tualle; Sigrid Avrillier
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Paper Abstract

We develop a new sensor for the local in vivo measurement of optical coefficients near the surface of a tissue. To be less sensitive to the heterogeneous surface of the sample, we decided to perform space and time-resolved measurements. The sensor is a bundle of fibres. The excitation light is generated by a mode-locked Ti-Sa laser at 800nm and filtered by a 1.5nm bandwidth dielectric filter in order to limit group velocity dispersion in the monomode excitation fibre. The reflectance light is collected by gradient index fibres at 250μm and 1.3 mm from the source. The detection is performed with a Hamamatsu M5675 synchroscan streak camera. The whole system allows a time resolution of about 5ps. We made comparisons between time and space resolved Monte-Carlo numerical simulations and in vitro experimental data obtained with unskimmed UHT milk which is a known reference medium. The system does not rely on the absolute value of the reflected light intensity nor depend on the intensity ratio between different fibres since the distance between the medium and the fibres as well as the fibres tip cleanness cannot be guaranteed in vivo. As a consequence we use global characteristic of the time resolved curves such as the FWHM and their evolution with the distance from the source. The good agreement between the simulations and the experimental data lets us envisage to use numerically pre-computed tables for a real time determination of the local scattering mean free path and the anisotropy factor . We soon will be able to perform measurements with biological tissues, in vitro in a first time and in vivo in a second time.

Paper Details

Date Published: 8 September 2004
PDF: 7 pages
Proc. SPIE 5463, Femtosecond Laser Applications in Biology, (8 September 2004); doi: 10.1117/12.548056
Show Author Affiliations
Dominique Ettori, Lab. de Physique de Lasers, CNRS and Univ. Paris-Nord (France)
Eric Tinet, Lab. de Physique de Lasers, CNRS and Univ. Paris-Nord (France)
Tuan Nguyen Tien, Center for Quantum Electronics (Vietnam)
Franck Revel, HIA Val de Grace (France)
Jean-Michel Tualle, Lab. de Physique de Lasers, CNRS and Univ. Paris-Nord (France)
Sigrid Avrillier, Lab. de Physique de Lasers, CNRS and Univ. Paris-Nord (France)


Published in SPIE Proceedings Vol. 5463:
Femtosecond Laser Applications in Biology
Sigrid Avrillier; Jean-Michel Tualle, Editor(s)

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