Patent ID: 8526286
Filing Date: 2013-09-03
Classification: G11B

Abstract:
1. An optical pick-up apparatus for reproducing information recorded on an optical recording medium or recording information on the optical recording medium comprising: a light source unit generating beams; a diffraction element which diffracts beams which are generated from the light source unit; and an objective lens which focuses a p order diffracted beam which is used for recording and reproducing information among a plurality of diffracted beams which are diffracted by the diffraction element on any one of a plurality of information recording layers which are formed on the optical recording medium, wherein a p±1 order diffracted beam which is not used for recording and reproducing information is focused on a point that is away from the plurality of information recording layers and a surface of the optical recording medium, wherein a difference (f 2×Dmax−Dmin+s×t≦f