Time-resolved diffuse reflectance using small source-detector separation and fast single-photon gating.
We demonstrate the feasibility of time-resolved diffuse reflectance measurements at small source-detector separations using a single-photon avalanche diode operated in time-gated mode. Photon time distributions at an interfiber distance of 2 mm were obtained on a homogeneous tissue phantom with a dynamic range of 10(6) and collecting photons at arrival times up to 4 ns. Moreover, we were able to detect a local inhomogeneity deeply buried within a diffusive medium with better spatial resolution, higher signal intensity, and same contrast of a larger (20 mm) interfiber distance. Finally, the proposed approach proved valuable to detect in vivo a task-related brain activation.
Pifferi
Antonio
A
IIT, ULTRAS-INFM-CNR and IFN-CNR, Dipartimento di Fisica, Politecnico di Milano, Piazza Leonardo da Vinci 32, I-20133 Milan, Italy.
Torricelli
Alessandro
A
Spinelli
Lorenzo
L
Contini
Davide
D
Cubeddu
Rinaldo
R
Martelli
Fabrizio
F
Zaccanti
Giovanni
G
Tosi
Alberto
A
Dalla Mora
Alberto
A
Zappa
Franco
F
Cova
Sergio
S
D001921:Brain / Q000502:physiology*; D006801:Humans; D054023:Lasers, Semiconductor; D009044:Motor Cortex / Q000502:physiology; D017785:Photons; D012815:Signal Processing, Computer-Assisted