Patent ID: 8004951

Claim:
A pickup device comprising: an irradiation optical system including an object lens for focusing light flux on a track of a recording surface of an optical recording media having a plurality of recording layers stacked while a spacer layer is interposed between the recording layers to form a spot; and a detection optical system including a photo detector having a plurality of light receiving parts for receiving returning light reflected from the recording layers through the object lens to perform photoelectric conversion, the pickup device controlling a position of the object leans according to an electrical signal calculated from outputs of the light receiving parts, wherein the pickup device further comprises: an astigmatic device for providing astigmatism to the returning light directed to the light receiving parts; and a division device, having divisional regions divided by a division line extending in an astigmatic direction about an optical axis of the returning light, for dividing the returning light having the astigmatism into a plurality of partial light fluxes divided for the respective divisional regions along the optical axis of returning light, wherein ones of the divisional regions neighboring each other provide the partial light fluxes with an optical action so that interference between the corresponding partial light fluxes does not occur on the light receiving parts.