The low frequency and d.c. components of the photo detector output are proportional to the average light intensity incident thereon, and an error signal derived from {HEAD ~ the comparison} thereof with {TAIL ~ a reference voltage} is compensated, amplified, and limited, and applied to a regulator to control the discharge current of a laser light source 
with
The low frequency and d.c . components of the photo detector output are proportional to the average light intensity incident thereon , and an error signal derived from { HEAD ~ the comparison } thereof with { TAIL ~ a reference voltage } is compensated , amplified , and limited , and applied to a regulator to control the discharge current of a laser light source
OTH OTH OTH OTH OTH OTH OTH OTH 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 OTH REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH