US Patent 7718939 Optical pickup apparatus

An optical pickup apparatus includes a light source to emit light of a predetermined wavelength, an objective lens to focus the light emitted from the light source to form a light spot on an optical disc having a plurality of recording layers, a photodetector to detect a signal and an error signal by detecting the light reflected from the optical disc, and a light scattering portion to reduce an amount of the light reflected from a non-target layer of the recording layers and incident on the photodetector by scattering part of the light reflected from the optical disc during a reproduction of data from the optical disc.