Source-detector pair
Definition: A set of two optodes (one light source and one detector) which is considered as a single measurement unit (i.e., measurement channel). Although in theory any source can be paired with any detector, most systems/researchers set up a region of interest- and a distance-criteria (how far away from each other are the two optodes located, i.e., source-detector separation) to define source-detector pairs that interrogate the brain. A single optode (either source or detector) can be part of multiple source-detector pairs.
Alternative definition:
Synonym: SD pair, measurement channel, S-D combination
References: https://doi.org/10.1118/1.1354627https://doi.org/10.1038/s41598-018-21716-z
Related terms: source, detector, array, optode, montage, High Density (Source-detector Array), measurement channel