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