Apparatus and method for detecting and compensating for pit extension in an optical disk recording system

摘要

A system for storing and retrieving encoded data on an optical recording medium using pit edge detection is disclosed. The pit extension characteristics of a given medium are determined by first using laser beam test write pulses to form one or more pits on the medium and then detecting the time durational difference between the pulse width of the test write pulses and the duration of the leading edge transitions to trailing edge transitions of the corresponding pits formed on said medium. This difference value may be stored in a certification sector of the medium. Subsequent write pulses are modified in duration in an amount equal to this detected durational difference. For forming a pit that is longer than a predetermined minimum length, the corresponding write pulse is made non-continuous in order to minimize cumulative pit extension. The number of non-continuous pulses used to form a given pit is a function of the desired length, the on time of each pulse and the duration of the off time between adjacent write pulses, said off time being a predetermined length to cause pit extension overlap between the portions of the pit formed during the one time of each said write pulse, thereby forming a continuous pit.