The imaging unit is arranged in front of the photosensor array such that it maps an image of {HEAD ~ said array} of {TAIL ~ LEDs} on said photosensor array 
The imaging unit is arranged in front of the photosensor array such that it maps an image of { HEAD ~ said array } of { TAIL ~ LEDs } on said photosensor array
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH