Patent ID: 6304526
Filing Date: 2001-10-16
Classification: G11B

Abstract:
An optical head comprising:a light source which emits a light beam; anda condenser which condenses the light beam emitted by said light source to form a light spot on a recording medium, said condenser comprising first and second object lenses mounted to a lens holder provided for a plurality of kinds of optical recording medium;wherein said first and second object lenses satisfy two conditions that.vertline.Lt1.vertline.>.vertline.Lt2.vertline.,and.vertline.Lb1.vertline.>.vertline.Lb2.vertline.,wherein Lt1 and Lt2 denote third order coma aberration components of wave front aberration that change when angles of optical axes of said first and second object lenses are varied by a unit angle, respectively, and Lb1 and Lb2 denote third order coma aberration components of wave front aberration that change when angles of incident light beams on said first and second object lenses are varied by a unit angle, respectively.