| 摘要 |
PURPOSE:To ensure the steady recording and reproduction of the information, by installing the polarized beam splitter into the optical path reaching the information recording medium from the light source in order to isolate the reflected light from the information recording medium to the optical path. CONSTITUTION:The lambda/4 plate 6 is put between information recording medium 2 and condensing lens 9 within the focus surface of condensing lens 9. Reflected light l3' from convex cylindrical lens 7 transmits toward convex cylindrical lens 4 without being reflected toward detector 11 and on polarizing face X. Accordingly, the optical image of reflected light l2' from medium 2 is not affected by the reflected light caused by light l3' and lens 9. On the other hand, the reflected light on face H of the upper part of plate 6 gives no floating light to detector 11, but the light reflected on lower face I enters lens 7 to be reflected by polarized beam splitter 1 toward detector 11. In this connection, face I of plate 6 is put more inside than the focal plane of lens 9. As a result, the dispersing light is obtained, and this light does not disturb the optical image on detector 11. |
