Perimeter receiver fiber optics/elements are spaced apart from a central source fiber optic/element and {HEAD ~ received light} reflected from {TAIL ~ the surface} of the object is measured 
reflected from
Perimeter receiver fiber optics / elements are spaced apart from a central source fiber optic / element and { HEAD ~ received light } reflected from { TAIL ~ the surface } of the object is measured
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH