Patent ID: 6963522
Filing Date: 2005-11-08
Classification: G11B

Abstract:
1. An optical head apparatus comprising: a light source; means for generating a main beam, first sub beams and second sub beams from incident light emitted from said light source; an objective lens which focuses said main beam, said first sub beams and said second sub beams on an optical recording medium; a photo detector which receives said main beam, said first sub beams and said second sub beams reflected from the optical recording medium; means for detecting a focusing error signal or a tracking error signal from each of said main beam, said first sub beams, and said second sub beams, the distribution of the intensity of the main beam being the same as the distribution of the intensity of the first sub beams, the distribution of the intensity of the main beam being different from the distribution of the intensity of the second sub beams.