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Proceedings Paper

Fast-gated single-photon avalanche diode for extremely wide dynamic-range applications
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Paper Abstract

Near-Infrared (NIR) picosecond pulsed light shined in biological tissues (e.g. brain, breast, muscle) offers the opportunity for non-invasive quantitative spectroscopy and imaging. Tissue optical properties determine high attenuation levels of optical signals and nanosecond scale dynamics. Therefore high-performance set-ups are needed. We aimed at developing a winning photodetector-electronics pairing for a broad field of multiple-wavelengths faint-signal optical investigations, like brain functional imaging, optical mammography, in-vivo spectroscopy, drugs characterization, molecular imaging. We present an electronic instrumentation based on silicon Single-Photon Avalanche Diode (SPAD) and fast-gating frontend electronics, in a Time-Correlated Single-Photon Counting (TCSPC) set-up. Detection efficiency is very high (50% at 550 nm and 15% at 800 nm), allowing acquisition of very faint optical signals on a wide spectral range. Furthermore, the fast-gating circuitry enables the detector very quickly (500 ps) and for user-selectable (200 ps - 510 ns) durations, thus allowing the rejection of very intense optical signals (e.g. scattered light from more superficial layers of the tissue under investigation) preceding useful faint signals (e.g. scattered light from sub-cellular components or coming from "deep" tissue layers), which would be otherwise overwhelmed and made undetectable. We attain photon-counting dynamic ranges up to 107 with photon-timing resolutions of 95 ps.

Paper Details

Date Published: 23 February 2009
PDF: 11 pages
Proc. SPIE 7170, Design and Quality for Biomedical Technologies II, 71700K (23 February 2009); doi: 10.1117/12.809205
Show Author Affiliations
A. Tosi, Politecnico di Milano (Italy)
A. Dalla Mora, Politecnico di Milano (Italy)
F. Zappa, Politecnico di Milano (Italy)
S. Cova, Politecnico di Milano (Italy)
D. Contini, Politecnico di Milano (Italy)
A. Pifferi, Politecnico di Milano (Italy)
L. Spinelli, Politecnico di Milano (Italy)
A. Torricelli, Politecnico di Milano (Italy)
R. Cubeddu, Politecnico di Milano (Italy)

Published in SPIE Proceedings Vol. 7170:
Design and Quality for Biomedical Technologies II
Ramesh Raghavachari; Rongguang Liang, Editor(s)

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