Apparatus and method for detecting land prepit

摘要

A filter generates a received-light signal LAD2 from which impulse components TR included in a received-light LAD1 have been removed. A filter generates a received-light signal LBC2 from which impulse components TR included in a received-light LBC1 have been removed. A subtracter subtracts a received-light signal WBC from a received-light signal WAD, thereby generating a radial push-pull signal WPP. A comparator compares the radial push-pull signal WPP from which the impulse components have been removed with a reference level VT, thereby detecting a land prepit.