| 摘要 |
<P>PROBLEM TO BE SOLVED: To form a successful spot in any of a plurality of kinds of optical recording media with one objective lens to more compactly arrange elements. <P>SOLUTION: In a blue/CD compatible optical pickup, an optical recording medium (CD system) 107a or an optical recording medium (blue system) 107b is set. At the time of recording, reproduction of the CD system optical recording medium, radiation light of a semiconductor laser 101a for CD opposite to the objective lens 105 via a dichroic prism 103 is made incident on the objective lens 105 through the dichroic prism 103 which performs dead zone transmission of a hologram element 102 for CD, transmits infrared wavelength light and reflects blue wavelength light and a quarter wavelength plate 104 with aperture restriction and condensed by the optical recording medium 107a. Reflected light of the optical recording medium 107a diffracts only a light beam of a backward path rotated in the perpendicular direction of a forward path on a hologram formation surface of the hologram element 102 for CD and is received by a light receiving element 101c for CD. High light use efficiency is secured both on the forward and backward paths by the hologram formation surface. <P>COPYRIGHT: (C)2006,JPO&NCIPI |
