A signal corresponding to {HEAD ~ a distance} from the present position of the laser beam spot to {TAIL ~ the desired track} is obtained from the displacement and a desired count value, and is inputted to a function generator to thus obtain a square root of the distance 
to
A signal corresponding to { HEAD ~ a distance } from the present position of the laser beam spot to { TAIL ~ the desired track } is obtained from the displacement and a desired count value , and is inputted to a function generator to thus obtain a square root of the distance
OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH 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 OTH OTH OTH OTH