Laser power control in an optical recording system to compensate for multiple system degradations

摘要

The present invention provides an apparatus and method for controlling laser power in an optical recording system in the presence of multiple system degradations. A recording system in accordance with the present invention includes an optical source for supplying an incident write signal to an optical medium, such that data may be recorded on the medium during an incident Write pulse as a mark having a distinct reflectivity; a structure for detecting a reflection of the incident write signal from the medium to provide a reflected write signal; means for generating a mark formation effectiveness signal from a reflected write pulse in the reflected write signal, to provide an indication of the quality of the mark; means for generating an error signal from the mark formation effectiveness signal and a target value of said mark formation effectiveness signal; and means for controlling a write power level of the optical source by providing a partial correction of a first type of variation in the error signal and a full correction of a second type of variation in the error signal. The first type of variations may be due to high frequency system degradations such as laser defocus and optical media tilt, while the second type of variation may be due to low frequency variations, such as changes in optical source wavelength or media sensitivity.