Each trough shaped reflector has an associated flat reflecting mirror for directing {HEAD ~ its beam} of {TAIL ~ illuminating light} toward the document 
of
Each trough shaped reflector has an associated flat reflecting mirror for directing { HEAD ~ its beam } of { TAIL ~ illuminating light } toward the document
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH