The integrity of a beam of light may be compromised by contamination from {TAIL ~ other light beams} giving rise to {HEAD ~ “cross talk}” 
The integrity of a beam of light may be compromised by contamination from { TAIL ~ other light beams } giving rise to { HEAD ~ “ cross talk } ”
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH