{HEAD ~ The detection unit} comprises a photosensor array, {TAIL ~ an imaging unit}, and a processing unit 
comprises
{ HEAD ~ The detection unit } comprises a photosensor array , { TAIL ~ an imaging unit } , and a processing unit
HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH