COMPOUND OPTICAL DEVICE AND OPTICAL PICKUP DEVICE

PROBLEM TO BE SOLVED: To provide a compound optical device which is inexpensive and permits reduction in man-hours of adjustment work at the time of assembly, and to provide an optical pickup having this compound optical device. SOLUTION: The compound optical device of this invention is used for the optical pickup device having a resin layer provided with a optical path difference-making structure on at least one optical surface of an aspheric lens. Then, a ratio of an optical path length L' when an incident luminous flux passes through the resin layer at the end of an effective diameter corresponding to a required numerical aperture to an optical path length L in the optical axis when the incident luminous flux passes through the resin layer satisfies a formula (1): 0.8≤(L'/L)≤1.2. COPYRIGHT: (C)2006,JPO&NCIPI