Optical pickup apparatus

An optical pickup apparatus for reading information from one of different kinds of optical information recording media, each medium having a transparent base board of a different thickness, or for recording information onto one of said different kinds of optical information recording media, the apparatus comprising:

• a laser light source;
• a light converging optical system for converging luminous flux from said laser light source through said transparent base board of said optical information recording medium onto an information recording surface of said optical information recording medium;
• wherein said light converging optical system includes an objective lens and divides a light flux from said laser light source into a light flux of a first region, being closest to an objective lens optical axis, a light flux of a second region, being outside of said first region, and a light flux of a third region, being outside of said second region in a direction perpendicular to a laser optical axis;
• said different kinds of optical information recording media include a first optical information recording medium, having a transparent base board with a thickness of t1, and a second optical information recording medium, having a transparent base board with a thickness of t2 wherein t2 is larger than t1;
• and a magnification m2 of said objective lens, viewed from a second optical information recording medium side in a recording or reading operation, is smaller than a than a magnification m1 of said objective lens, viewed from a first optical information recording medium side in a recording or reading operation information;
• and said light flux of said first region is used for recording or reading information of said first optical information recording medium and said second optical information recording medium and said light flux of said third region is used for recording or reading information of said first optical information recording medium;
• and
• wherein said light flux of said first region, said light flux of said second region and said light flux of said third region are substantially coaxial with the objective lens optical axis.