{HEAD ~ The photosensor array} is divided into {TAIL ~ subareas} each detecting light output from a single one of said LEDs 
is divided into
{ HEAD ~ The photosensor array } is divided into { TAIL ~ subareas } each detecting light output from a single one of said LEDs
HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL REL REL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH