Dynamic tracking control in an optical recording system by diffraction-based mark formation detection

Abstract

An apparatus and method for providing dynamic tracking error detection and control in an optical recording system in which an incident beam records data on a medium in the form of marks. A diffraction-based mark formation effectiveness (MFE) signal is generated by monitoring a reflected write signal in part of the return beam aperture or in multiple zones of the return beam aperture and is indicative of a characteristic of the marks formed on the medium. A position signal is generated to provide an indication of cross-track movement of the incident beam relative to a tracking structure on the medium. The tracking structure may be a wobbled groove on an optical disk recording medium. Variations in the diffraction-based MFE and position signals are correlated to provide a dynamic tracking error signal (TES). The diffraction-based MFE and position signal variations may be correlated by, for example, multiplying the two signals together in a multiplier circuit, or using the position signal to control application of the diffraction-based MFE signal to particular inputs of a signal difference circuit. The dynamic TES may be utilized in a servo loop with or without a push-pull signal or other conventional tracking signal.

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