| 摘要 |
PROBLEM TO BE SOLVED: To obtain an optical pickup device by which an optical disk using a thin substrate and an optical disk having a standard thickness as in conventional cases can be used in common by a method wherein a deflection-face rotation means and a phase conversion means are provided between a collimating lens and an objective lens. SOLUTION: A luminous flux which is radiated from a semiconductor laser 21 is converted into a nearly parallel luminous flux by a collimating lens 22, it is transmitted through a returned-light separation prism 23, it is passed further through an objective lens 24, and its image is formed as a very small light spot on a recording face 26 at the bottom face of a thin high-density optical disk substrate 25. In addition, reflected light which is reflected here and which contains information is converted into nearly parallel light by the objective lens 24. In addition, the light which is separated from a forward passage clue to the action of a light separation face 27 formed at the inside of the returned- light separation prism 23 is passed through a condensing lens 28 and a cylindrical lens 29, and it is incident on a light detection part 30 while it is being converged. Then, it is photoelectrically converted so as to be sent to a signal processing part. |
