LIGHT SPOT INSPECTION DEVICE AND OPTICAL SUBSTRATE FOR ABERRATION CORRECTION USED FOR THIS DEVICE AS WELL AS OPTICAL PICKUP DEVICE SUBJECTED TO INSPECTION OF LIGHT SPOT SHAPE BY USING THIS DEVICE

摘要

PROBLEM TO BE SOLVED: To provide a light spot inspection device which is capable of realizing aberration correction under different conditions with one pseudo disk without using an intricate switching mechanism and an optical substrate used for this device. ;SOLUTION: This light spot inspection device 10 is used to inspect the shape of a light spot which is emitted from a light source 2 and is focused near the recording surface 6a of the disk 6 which is an information recording medium via optical systems 3 (31, 32, 33 and 5). The device is constituted by arranging the optical substrate 21 for aberration correction having a variable reflection surface changed in its transmission and/reflection ratio by the wavelength of the light emitted from the light source 2 between an objective lens 11a of the light spot inspection device 10 and an objective lens 5 of the optical pickup device 1 for the optical disk. The optical path length within the optical substrate 21 of the light, which is emitted from the light source and for which the aberration correction more than the thickness size of the optical substrate 21, is assured by suitably utilizing the transmitted light and reflected light at the variable reflection surface, by which the desired aberration correction is made possible.;COPYRIGHT: (C)2001,JPO