Instrumentation for fast functional optical tomography

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Abstract
In this article, we describe the design rationale and performance features of an integrated multichannel continuous wave (cw) near-infrared (NIR) optical tomographic imager capable of collecting fast tomographic measurements over a large dynamic range. Fast data collection (∼70 Hz/channel/wavelength) is achieved using time multiplexed source illumination (up to 25 illumination sites) combined with frequency encoded wavelength discrimination (up to four-wavelength capability) and parallel detection (32 detectors). The described system features a computerized user interface that allows for automated system operation and is compatible with various previously described measuring heads. The results presented show that the system exhibits a linear response over the full dynamic measuring range (180 dB), and has excellent noise (∼10 pW noise equivalent power) and stability performance (<1% over 30 min). Recovered images of laboratory vessels show that dynamic behavior can be accurately defined and spatially localized.