c) detecting light of {HEAD ~ such wavelength} that is reflected or scattered by {TAIL ~ the sheet}, and 
is reflected by
c ) detecting light of { HEAD ~ such wavelength } that is reflected or scattered by { TAIL ~ the sheet } , and
OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH REL REL OTH OTH REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH