To carry out these operations, the optical head 13 is moved radially over {HEAD ~ the optical disk} 11, so that {TAIL ~ a laser beam spot} is positioned at a predetermined track 
To carry out these operations , the optical head 13 is moved radially over { HEAD ~ the optical disk } 11 , so that { TAIL ~ a laser beam spot } is positioned at a predetermined track
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH