Near-infrared topographic measurement system: Imaging of absorbers localized in a scattering medium

We developed a multichannel reflectance measurement system that uses near-infrared measurements for topographic imaging inside biological tissue. In this system, nine incident and four detecting optical fibers are arranged alternately at square lattice points on the sample. Source light is optically demultiplexed with an optical fiber switch, and connected to one of the incident fibers. Reflected light from the sample is received by the detecting fibers each of which is connected to a photodiode. The photodiode outputs are multiplexed. Sixteen combinations of neighboring incident and detecting fibers correspond to 16 measurement channels. These channels are selected sequentially with the optical fiber switch and the multiplexer. The system was used to obtain topographic images of absorbers in the scattering medium that simulated biological tissue. (C) 1996 American Institute of Physics.