The output signal from this optical detector 7 is sent via {TAIL ~ the preamplifier} to the RMS DC 18, which converts the amplitude into {HEAD ~ a dc voltage} 
The output signal from this optical detector 7 is sent via { TAIL ~ the preamplifier } to the RMS DC 18 , which converts the amplitude into { HEAD ~ a dc voltage }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD