单光子雪崩二极管
纳秒
光电子学
动态范围
光电探测器
光子计数
雪崩光电二极管
雪崩二极管
探测器
光子
高动态范围
皮秒
光学
衰减
物理
功能近红外光谱
硅光电倍增管
材料科学
激光器
闪烁体
击穿电压
电压
神经科学
认知
量子力学
前额叶皮质
生物
作者
Alberto Tosi,Alberto Dalla Mora,Franco Zappa,S. Cova,Davide Contini,Antonio Pifferi,Lorenzo Spinelli,Alessandro Torricelli,Rinaldo Cubeddu
摘要
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.
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