RECORDING/REPRODUCING METHOD OF OPTICAL INFORMATION RECORDING MEDIUM, OPTICAL PICKUP DEVICE, CONDENSER OPTICAL SYSTEM, OBJECTIVE LENS AND METHOD FOR DESIGNING OBJECTIVE LENS

摘要

PROBLEM TO BE SOLVED: To reproduce plural optical disks with one condenser optical system, to embody the reproduction at a low cost without complication and to deal with the optical disk of high NA as well. SOLUTION: The refraction surface S1 on the light source side of the objective lens 16 of the optical pickup device is provided with three splitting surfaces Sd1 to Sd3. The luminous fluxes passing the first splitting surface Sd1 and the third splitting surface Sd3 are utilized at the time of reproducing the first optical disk of t1 in the thickness of a transparent substrate and the luminous fluxes passing the first splitting surface Sd1 and the second splitting surface Sd2 are utilized at the time of reproducing the second optical disk of t2 (t2≠t1) in the thickness of the transparent substrate.