Thus, a signal proportional to the total amount of {HEAD ~ light} received by the photo detecting elements 6a and {TAIL ~ 6b} is supplied to the light intensity control circuit D 
received by
Thus , a signal proportional to the total amount of { HEAD ~ light } received by the photo detecting elements 6a and { TAIL ~ 6b } is supplied to the light intensity control circuit D
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD REL REL OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH