means for regulating comprises a transistor circuit for controlling {HEAD ~ the discharge current} from {TAIL ~ the source} of laser light 
from
means for regulating comprises a transistor circuit for controlling { HEAD ~ the discharge current } from { TAIL ~ the source } of laser light
OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH