OBJECTIVE LENS FOR LIGHT PICKUP DEVICE, LIGHT PICKUP DEVICE, AND LIGHT INFORMATION RECORDING/REPRODUCTION DEVICE

摘要

When focusing, other than a main FE signal (m) expressing a correct focus position, a fake FE signal (f) expressing an incorrect focus position is only produced in a single location; therefore, it is possible to easily identify the main FE signal (m), and to significantly reduce the danger of incorrect detection.