By these means, the measurement range determines that range in which the transmitting light spot lies almost completely in {HEAD ~ the field} of {TAIL ~ view} of the receiving optic 
of
By these means , the measurement range determines that range in which the transmitting light spot lies almost completely in { HEAD ~ the field } of { TAIL ~ view } of the receiving optic
OTH OTH 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 TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH