Focus error detecting device

Focus error detecting method and optical head using the same

Focus error detection system for an optical recording/reproducin

Focus error detection using an equal path length lateral shearin

Focus error signal generation using a birefringent lens with...

Focus error signal generation using a birefringent plate...

Focus error signal generation using confocally filtered detectio

Focus error signal generation using two polarizers in...

Focus jump control apparatus of a player for multilayer recordin

Focus jump device for reproducing information from a storage...

Focus layer jump control circuits and methods of controlling...

Focus offset calibration

Focus offset correction method

Focus offset optimization for reading optically recorded data

Focus point switching

Focus position adjustment device and optical disc drive...

Focus pull-in method and optical disk device

Focus search apparatus and method

Focus search method and controller for digital disk

Focus searching method and optical disc device