| 摘要 |
PURPOSE: A compatible optical pick-up unit for heterogeneous recording media is provided to use one objective lens for both an HD disk and a DVD, thereby simplifying a structure of an optical system. CONSTITUTION: An objective lens(21) is formed by cutting a paraboloid lens in a direction crossing a major axis of an oval so that a focus of the oval is located in a random space outside a lens body. HOE(Holographic Optical Element) patterns(22) are formed on an incident plane of the objective lens. A reflective plane(21a) for waveguide and a paraboloid reflective plane(21b) for focusing are formed inside the objective lens. An HD disk(23) and a DVD(24) are put in a focusing direction of an emitting plane of the objective lens. |
