System and method of recording and reproducing information

System and method to adjust the level of re-calibration...

System for actively controlling the lense of an optical...

System for calculating focus servo control signal using focus er

System for compensating for hard sector noise degradation of tra

System for compensating for hard sector noise degradation of tra

System for creating, reading and writing on rotatable informatio

System for creating, reading and writing on rotatable informatio

System for creating, reading and writing on rotatable informatio

System for creating, reading and writing on rotatable informatio

System for creating, reading and writing on rotatable informatio

System for creating, reading and writing on rotatable informatio

System for creating, reading and writing on rotatable informatio

System for creating, reading and writing on rotatable informatio

System for creating, reading and writing on rotatable informatio

System for enhanced astigmatic focus signal detection

System for performing focusing operation when recording and/or r

System for recording data on spiral track

System for reproducing pulse time modulated wave forms stored al

System having optical disk and disk drive unit