Optical memory system having a long seek capability

Abstract

A high density optical storage system employing a laser beam for reading data in a track on a rotating optical disk containing a large number of closely spaced concentric tracks. When a long seek operation is to be provided, track following is suspended and a linear motor drives a galvanometer-controlled mirror to a new position corresponding to a new track called for by the long seek operation. Arrival at the new position is determined by detecting when both the velocity of the linear motor and the difference between current and desired positions are below predetermined maximum values indicating that a stable condition has been reached, after which track following operation is resumed. The linear motor also operates during track following in response to the detected angular position of the mirror so as to cause movement of the mirror in a direction which reduces the mirror deflection required to maintain the beam accurately following the track.