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