基于差分时间数字转换光子计数技术的时域扩散光学成像系统研究
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关键词：时域扩散光学成像;时间相关单光子计数;时间数字转换;光学参数反演中图分类号：0434 文献标志码：A doi：10.37188/CO.2025-0048 CSTR：32171.14.CO.2025-0048
Abstract： Time-domain diffuse optical imaging （TD-DOI） is an advanced tissue optical imaging technique.Utilizing a time-correlated single-photon counting （TCSPC） system， it enables the quantitative reconstruction of tissue absorption and scattering coefficients.This facilitates the precise assessment of key physiological parameters，such as tissue oxygen metabolism and blood perfusion. However， due to the inherent hardware complexityand high cost of TCSPC systems，it is currently challenging to meet the requirements for scaled，multichannel， dynamic in vivo monitoring in clinical setings.This paper develops a dual-channel differential hybrid triggerand reference signal strategy.Byintegratingadifferential time-to-digital converter （TDC） device with photon counting technology， we construct a stable and reliable time point spread function （TPSF） measurement system. This system achieves sub-nanosecond precision in calibrating the time delay between the laser synchronization signal and emited photon signals.Experimental validation demonstrates a system temporal resolution of 55 ps. At a photon count rate of 2.3×104 photons per second， the TPSF fluctuation coefficient remains below 1.35% （with an integration time of 1 s）. Optical parameter inversion tests on tissue-simulating phantoms demonstrate average inversion errors of 5.39% for the absorption coefficient and 4.34% for the reduced scattering coefficient. This technological approach significantly advances the feasibility of multichannel parallel detection for TD-DOI.It is particularly suitable for biomedical applications demanding dynamic monitoring，such as cerebral cortical hemoglobin oxygen saturation， and lays the technical groundwork for developing next-generation wearable optical brain functional imaging devices.
Key words： time domain diffuse optical imaging; time-correlated single photon counting; time-to-digital converter; optical properties inversion
1引言
扩散光学成像（diffuseoptical imaging，DOI）作为一种非侵入式组织光学成像技术，利用近红外光谱窗口（ 600～950nm 对生物组织相对“透明”的特点，使得人射光子能在安全功率范围内穿透深层生物组织（几个厘米到十几个厘米）。（剩余12332字）
