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