INFORMATION REPRODUCING DEVICE AND OPTICAL RECORDING MEDIUM

摘要

PROBLEM TO BE SOLVED: To provide an information reproducing device and an optical recording medium which can detect spherical aberration quickly without requiring a special optical system. SOLUTION: This information reproducing device has a focusing means to condense the signal reading probe light on an optical recording medium, a focusing servo means to maintain the focus on the recording surface of the optical recording medium using the focusing means, and an offset means to give a predetermined offset to the target of the focusing servo means. It is constituted so that it has a spherical aberration detecting means to detect the signals corresponding to the spherical aberration included in the probe light on the basis of the reproduced signal strength to the two or more targets obtained by the offset means in the signal of predetermined spatial frequency recorded on the optical recording medium.