| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an optical pickup device reducing coma and spherical aberrations and astigmatism while making beams having an ideal intensity distribution incident on an objective lens. <P>SOLUTION: In the optical pickup device 10 for emitting beams of different wavelengths from light sources 1 and 2, and transmitting the beams through a common collimator lens 5 and a common objective lens 8 to irradiate an optical disk 11 with the beams, one beam is emitted as an infinite beam from the collimator lens 5 and the other beam as a finite beam from the collimator lens 5. Between the lenses 5 and 8, there is provided a beam shaping element 6 constituted of a wedge-shaped light transmissive prism for making the beam emitted from the collimator lens 5 incident from one surface, reflecting it on the other opposite surface, emitting it toward the objective lens 8 from one surface, and converting the aspect ratio of the beam. In the other surface of the element 6, there is provided a diffraction grating 7 patterned for correcting wavelength dispersion characteristics of the element 6 and astigmatism generated for the finite beam by the element 6 is disposed. <P>COPYRIGHT: (C)2008,JPO&INPIT |
