Electro-optic apodization having backward compatibility and discrimination capabilities for optical disk drives

Abstract

The present invention preferably includes a shading band which is suitably electro-optically created in a grid pattern formed through a photolithographic process, so consequently, the electro optic shading band is easily eliminated or re-configured dynamically to substantially eliminate its shading effect for lower density optical disks which do not experience substantial adjacent track crosstalk (ATC). Eliminating or reconfiguring the shading effect also helps in accommodating different media types and generations and those of different manufacturers. Moreover, the electro-optic shading band suitably adjusts the amplitude, phase, frequency, polarization and/or the like of the light beam to compensate for possible material property variations, defects, misalignments or other imperfections in the reading process. The present electro-optic shading band substantially restricts or alters any portion of a light beam containing signal information read from an optical disk. In a preferred embodiment, the electro-optic shading band reduces undesired portion of the low frequency distribution in the diffraction pattern of the readout beam which results from reading marks in high density optical disks, thereby enhancing the signal relative to the noise and crosstalk in high performance optical disk drives.