Eccentricity Compensation Mechanism for Improving Reliability of Removable Performance in Near-Field Optical Disc Drive System

Abstract

In this paper, we propose the eccentricity-compensating actuator mechanism for near-field (NF) optical disc drives. In this proposed dual-stage compensating actuator mechanism, the disc-spindle unit is actuated instead of the solid immersion lens (SIL) along the tracking axis to cancel out an eccentricity less than 20 µmpp (pp: peak to peak), which is the required criterion for NF discs of 160 nm track pitch. As a result, the proposed method enables the decrease in the required residual tracking error to lower than the criteria of 4.5 nm in NF optical disc drive (ODD) even when using the tracking servo of moderate performance. The proposed active eccentricity compensation method can be effective and applicable to dealing with the eccentricity problem in NF ODD, which we verified experimentally.