| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an optical head in which a signal outputted from a photodetector for the light source light quantity control depends only on the light quantity emitted from a light source while the spherical aberration that occurs when the base member thickness of an optical recording medium is different from a reference value but is corrected. <P>SOLUTION: This optical head for recording and/or reproducing a signal to/from the optical recording medium 10 has an aperture 16H for an objective lens for determining the aperture of an objective lens 9, spherical aberration correcting means 5 and 6 for correcting the spherical aberration that occurs when the base member thickness of the optical recording medium deviates from the reference value, an aperture 17H for the light source light quantity control for applying aperture restriction of the light separated by a light separating means 7, a photodetector 15 for receiving the light subjected to aperture restriction, and a photodetector 13 for receiving the light reflected from the optical recording medium. Optical path lengths of the both apertures up to the spherical aberration correcting means are set to be substantially equal, and the aperture sizes of the both apertures are set to be substantially equal. <P>COPYRIGHT: (C)2005,JPO&NCIPI |
