As such, it is possible to obtain a detection signal proportional to {HEAD ~ the amount} of {TAIL ~ actually reflected light}, i.e. the average light superimposed by the varying light component, incident on the photo detector 6 
of
As such , it is possible to obtain a detection signal proportional to { HEAD ~ the amount } of { TAIL ~ actually reflected light } , i.e. the average light superimposed by the varying light component , incident on the photo detector 6
OTH 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 TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH