Laser power control in an optical recording system to compensate for variations in mark length resulting from a wobbled groove

An apparatus for use in an optical recording system, the system including an optical source which provides an incident write signal for recording data in the form of optically-detectable marks on a medium having a wobbled groove, the apparatus comprising:

• a detector arranged in an optical path of a reflection of said incident write signal from said medium and adapted to generate a reflected write signal including at least one reflected write pulse corresponding to a portion of said data;
• a signal generator connected to said detector and adapted to generate from said at least one reflected write pulse a mark formation effectiveness (MFE) signal indicative of formation of the corresponding mark on said medium;
• said signal generator further adapted to exhibit substantially no amplitude and phase variation for a range of frequencies including both a low frequency component and a wobble frequency component of said MFE signal;
• and
• a feedback circuit connected between said signal generator and said optical source for controlling a power level of said source in accordance with MFE signal variations produced by said wobbled groove.

An apparatus for use in an optical recording system, the system including an optical source which provides an incident write signal for recording data in the form of optically-detectable marks on a medium having a wobbled groove, the apparatus comprising:

• a detector arranged in an optical path of a reflection of said incident write signal from said medium and adapted to generate a reflected write signal including at least one reflected write pulse corresponding to a portion of said data;
• first and second signal generators connected to said detector and adapted to generate from said at least one reflected write pulse first and second mark formation effectiveness (MFE) signals, respectively, indicative of formation of the corresponding mark on said medium;
• and
• a feedback circuit connected between said first and second signal generators and said optical source for processing a wobble frequency component of said first MFE signal to correct said source power level for wobble-induced variations in said first MFE signal and a low frequency component of said second MFE signal to correct said source power level for system degradation-induced variations in said second MFE signal.

An apparatus for use in an optical recording system, the system including an optical source which provides an incident write signal for recording data in the form of optically-detectable marks on a medium having a wobbled groove, the apparatus comprising:

• a detector arranged in an optical path of a reflection of said incident write signal from said medium and adapted to generate a reflected write signal including at least one reflected write pulse corresponding to a portion of said data;
• a signal generator connected to said detector and adapted to generate from said at least one reflected write pulse a mark formation effectiveness (MFE) signal indicative of formation of the corresponding mark on said medium;
• and
• a feedback circuit connected between said signal generator and said optical source for controlling a power level of said source in accordance with MFE signal variations produced by said wobbled groove, said feedback circuit further including means for defining a first signal path for processing a wobble frequency component of said MFE signal and means for defining a second signal path for processing a low frequency component of said MFE signal.

A method for use in an optical recording system, the system including an optical source which provides an incident write signal for recording data in the form of optically-detectable marks on a medium having a wobbled groove, the method comprising the steps of:

• detecting a reflection of said incident write signal from said medium to generate a reflected write signal including at least one reflected write pulse corresponding to a portion of said data;
• generating from said at least one reflected write pulse a mark formation effectiveness (MFE) signal indicative of formation of the corresponding mark on said medium;
• band pass filtering said MFE signal to pass components thereof in a frequency range centered about said wobbled groove frequency;
• and
• controlling a power level of said source in accordance with MFE signal variations produced by said wobbled groove.

A method for use in an optical recording system, the system including an optical source which provides an incident write signal for recording data in the form of optically-detectable marks on a medium having a wobbled groove, the method comprising the steps of:

• detecting a reflection of said incident write signal from said medium to generate a reflected write signal including at least one reflected write pulse corresponding to a portion of said data;
• generating from said at least one reflected write pulse a mark formation effectiveness (MFE) signal indicative of formation of the corresponding mark on said medium by a signal generator which exhibits substantially no amplitude and phase variation for a range of frequencies including both a low frequency component and a wobble frequency component of said MFE signal;
• and
• controlling a power level of said source in accordance with MFE signal variations produced by said wobbled groove.

A method for use in an optical recording system, the system including an optical source which provides an incident write signal for recording data in the form of optically-detectable marks on a medium having a wobbled groove, the method comprising the steps of:

• detecting a reflection of said incident write signal from said medium to generate a reflected write signal including at least one reflected write pulse corresponding to a portion of said data;
• generating from said at least one reflected write pulse first and second mark formation effectiveness (MFE) signals indicative of formation of the corresponding mark on said medium;
• processing a wobble frequency component of said first MFE signal to correct said source power level for wobble-induced variations in said first MFE signal;
• and
• processing a low frequency component of said second MFE signal to correct said source power level for system, degradation-induced variations in said second MFE signal.

A method for use in an optical recording system, the system including an optical source which provides an incident write signal for recording data in the form of optically-detectable marks on a medium having a wobbled groove, the method comprising the steps of:

• detecting a reflection of said incident write signal from said medium to generate a reflected write signal including at least one reflected write pulse corresponding to a portion of said data;
• generating from said at least one reflected write pulse a mark formation effectiveness (MFE) signal indicative of formation of the corresponding mark on said medium;
• and
• controlling a power level of said source by processing a wobble frequency component of said MFE signal in a first signal path and a low frequency component of said MFE signal in a second signal path.