Patent ID: 8625396

Claim:
An optical pick-up comprising: a light source; a first objective lens configured to focus light emitted from the light source on a high-density optical information storage medium; a photo-detector configured to detect a signal by receiving light reflected from the high-density optical information storage medium; an optical-path changer configured to convert a travel path of incident light to allow the light emitted from the light source to proceed toward the high-density optical information storage medium, and to allow the light reflected from the high-density optical information storage medium to proceed toward the photo-detector; a blocking device disposed in an optical path of signal light reflected from a target reproducing/recording layer of the high-density optical information storage medium, passes through the first objective lens, and proceeds toward the photo-detector, wherein the blocking device includes a blocking region around a signal light transmission region to block interlayer interference light reflected from a layer other than the target reproducing/recording layer, in response to the high-density optical information storage medium having a plurality of recording layers, and in order to pass the signal light without blocking the signal light in response to the first objective lens being shifted due to actuating, the signal light transmission region of the blocking device is formed to configure a width of the signal light transmission region in the shift direction of the first objective lens is greater than a width of the signal light; and a hologram device disposed in an optical path between the blocking device and the photo-detector and having a hologram region configured to divide a portion of a light region of the signal light into 0 th -order light and first-order light to obtain a tracking error signal from a detection signal of the first-order light.