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Updated: Sep 13, 2026

New Framework for Understanding Cross-Brain Coherence in Functional Near-Infrared Spectroscopy (fNIRS) Hyperscanning Studies
Published on: October 6, 2023
Is there a fundamental limitation on the measurement of spatial coherence for highly incoherent fields?
1Theory Division, T-4 Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA. jcat@lanl.gov
Abstract:
We investigate a fundamental limitation on the measurement of spatial coherence for highly incoherent fields. We model the near-field detection scheme, required for such a measurement, with pointlike induced dipoles. We find that this fully vector model sets a characteristic length scale beyond which the spatial coherence of an optical field cannot be accurately measured. This length scale forms an uncertainty relationship with the photodetector integration time.
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