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