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