| 摘要 |
PURPOSE:To obtain an inexpensive and compact astigmatic optical pickup, by using a 1/4 wavelength plate, a column surface lens of a large curvature radius, a reflecting mirror and a polarized beam splitter in place of a column surface lens of a small curvature radius. CONSTITUTION:A 1/4 wavelength plate 10, a column surface lens 20 of a large curvature radius and a reflecting mirror 30 are arrange at the exit side of the disk reflected light of a polarized beam splitter 2. At the same time, a 4-split optical sensor 8 is provided at the reflecting surface side of the exit surface of the disk reflected light of the splitter 2. A concave lens 40 can obtain a circular beam of a desired diameter at the center of the sensor 8 when a disk 6 has a focused state. |
