| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an optical pickup device which does not require a lens with a special function free of versatility to cancel astigmatism generated by a plane-parallel plate beam splitter when the direction of the astigmatism generated by the plane-parallel plate beam splitter is not in a direction proper for focus control for a dividing line direction of a photodetection area of an optical detector. <P>SOLUTION: A first plane-parallel plate 12 is arranged between the plane-parallel plate beam splitter 7 and photodetector 14 while tilted in the direction rotated π/2 radians around the optical axis with respect to the beam splitter 7, and a second plane-parallel plate 13 is disposed while tilted in a direction of rotation around the optic axis such that the direction of astigmatism projected on light receiving regions of the photodetector 14 has an angle of π/4 radians relative to each of dividing lines, wherein astigmatism generated by the beam splitter 7 is canceled and astigmatism used for focus control is generated by at least the two first and second plane-parallel plates. <P>COPYRIGHT: (C)2006,JPO&NCIPI |
