{HEAD ~ an actuator} for moving either the pinhole plate or the focusing lens to control {TAIL ~ the amount} of the first portion of the focused laser beam passing through the pinholes for replaying a target track on the holographic medium, 
{ HEAD ~ an actuator } for moving either the pinhole plate or the focusing lens to control { TAIL ~ the amount } of the first portion of the focused laser beam passing through the pinholes for replaying a target track on the holographic medium ,
HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH 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