Patent ID: 6717897
Filing Date: 2004-04-06
Classification: G11B

Abstract:
An optical pickup apparatus comprising:a light source having at least one light generation point irradiating a light beam; an objective lens irradiating said light beam onto a signal recording surface of an optical recording medium; and optical detection means for receiving a reflected light beam from the signal recording surface of said optical recording medium, wherein a light beam irradiated from said light source comprises a primary light beam which forms a primary spot for recording and/or reproducing an information signal on the signal recording surface of said optical recording medium and a secondary light beam which forms a secondary spot at a position apart from said primary spot on the signal recording surface of said optical recording medium; said secondary light beam differs from said primary light beam in a distance from an objective lens to a beam-condensing point and this distance difference Def satisfies a range: 0.4Ã—Def0&lE;Def&lE;1.7Ã—Def0 assuming that a light emission wavelength for said light source is &lgr;, a track pitch of said optical recording medium is Tp, and a numerical aperture of said objective lens is NA and that Def0=[0.178&lgr;/{1âˆ’cos(sinâˆ’1 NA)}]Â·[{1=(&lgr;/(TpÂ·NA))}+2.35].