An optode for a functional infrared diffuse optical neuroimaging system uses a GRIN lens and prism for coupling to an optical fiber at a right-angle to the lens. The lens is inserted into a grommet for attachment to an elastomeric cap worn by a subject. In an embodiment, the cap also has an array of electroencephalographic electrodes, with optodes arranged such that an optical path exists between a transmitter and a receiver optode beneath each electroencephalographic electrode. In an embodiment, quadfurcated optical cabling is used to permit illumination of each of multiple optodes with wavelengths provided from each of multiple lasers, and permitting each laser to illuminated multiple optodes.