Patent ID: 7965594

Claim:
An optical pickup comprising: a semiconductor laser light source; a beam splitting element having the function to split a laser optical beam emitted from said semiconductor laser light source into a main optical beam and sub-optical beams; an objective lens for focusing the main optical beam and each of the sub-optical beams on a predetermined recording layer provided in an optical information recording medium; and a photodetector for independently receiving reflections of the main optical beam and sub-optical beams from said recording layer to detect predetermined signals, wherein the photodetector includes a light receiving plane for main optical beam on which the main optical beam is incident and which is divided into four divisional areas by two mutually substantially orthogonal sectioning lines; and light receiving planes for sub-optical beams on which the sub-optical beams are incident and each of which is divided into four divisional areas by two mutually substantially orthogonal sectioning lines and being capable of detecting a focus control signal based on an astigmatism scheme wherein the light receiving planes for sub-optical beams each further includes a strip-shaped light shielding zone provided on and near any of the two sectioning lines provided for the light receiving plane for sub-optical beams and having a predetermined width and substantially completely blocking the incident light, and wherein the light shielding zone has a wavelength-selectability which exhibits a different transmission factor in accordance a wavelength band of the laser optical beam such that the transmission factor becomes substantially zero for a predetermined wavelength band of the laser optical beam.