Abstract: An optical pickup device enables prevention of an increase of spherical aberration during tracking without needing any finite optical system. The diameters of parallel light beams (A, B, C) for the next-generation DVDs, DVDs, and CDs are limited to diameters of a, b, c (a>b>c) in accordance with the NA for each type by a light beam limiting element, the diameter of light beam B is limited to the diameter ranges of b to c and d (=0.85×c) to e (d>e>0), the diameter of the light beam C is limited to the diameter ranges of c to d and less than e. They are passed through a phase correcting element (13B) and focused on the corresponding optical recording medium signal planes by means of a common objective lens. The objective lens is so optimized that the wave front aberration to the light beam A is minimum on the signal plane of the next generation DVD.

Abstract: An optical pickup device enables prevention of an increase of spherical aberration during tracking without needing any finite optical system. The diameters of parallel light beams (A, B, C) for the next-generation DVDs, DVDs, and CDs are limited to diameters of a, b, c (a>b>c) in accordance with the NA for each type by a light beam limiting element, the diameter of light beam B is limited to the diameter ranges of b to c and d (=0.85×c) to e (d>e>0), the diameter of the light beam C is limited to the diameter ranges of c to d and less than e. They are passed through a phase correcting element (13B) and focused on the corresponding optical recording medium signal planes by means of a common objective lens. The objective lens is so optimized that the wave front aberration to the light beam A is minimum on the signal plane of the next generation DVD.

Abstract: A fine displacement detection device by sound or the like: which can easily align individual optical components; which disposes a light emitting element (13) and a light receiving element (14) on a substrate, emits light from the light emitting element (13) to a diaphragm (I) set at a position facing the substrate, receives light reflected from the diaphragm (1) by the light receiving element (14), and detects as an electric signal the fine displacement of the diaphragm (1) by sound or the like; and which provides, on the optical paths of the substrate and the diaphragm (1), a focusing element (2) that focuses an incidence light from the light emitting element (13) for leading to the diaphragm (1) and focuses a diverged/reflected light from the diaphragm (1) for leading to the light receiving element (14), and a reflected light flux dividing element (3) that divides the diverged/reflected light focused by the focusing element (2) for leading to the light receiving element (14).

Abstract: A displacement/quantity of light converter in which sensitivity to a micro displacement due to sound of a diaphragm, or the like, can be enhanced easily. In the displacement/quantity of light converter where a light emitting part (2) and a light receiving part (3) are disposed oppositely to a diaphragm (1), light emitted from the light emitting part (2) and reflected off the diaphragm (1) is received at the light receiving part (3), and a displacement of the diaphragm (1) is converted into an output from the light receiving part (3), a concave diaphragm is used and the concave face is directed toward the light emitting part (2) and the light receiving part (3). According to the arrangement, light emitted from the light emitting part (2) and reflected off the diaphragm (1) impinges efficiently on the light receiving part (3) in the form of focused light.

Abstract: A fine displacement detection device by sound or the like: which can easily align individual optical components; which disposes a light emitting element (13) and a light receiving element (14) on a substrate, emits light from the light emitting element (13) to a diaphragm (1) set at a position facing the substrate, receives light reflected from the diaphragm (1) by the light receiving element (14), and detects as an electric signal the fine displacement of the diaphragm (1) by sound or the like; and which provides, on the optical paths of the substrate and the diaphragm (1), a focusing element (2) that focuses an incidence light from the light emitting element (13) for leading to the diaphragm (1) and focuses a diverged/reflected light from the diaphragm (1) for leading to the light receiving element (14), and a reflected light flux dividing element (3) that divides the diverged/reflected light focused by the focusing element (2) for leading to the light receiving element (14).

Abstract: A displacement/quantity of light converter in which sensitivity to a micro displacement due to sound of a diaphragm, or the like, can be enhanced easily. In the displacement/quantity of light converter where a light emitting part (2) and a light receiving part (3) are disposed oppositely to a diaphragm (1), light emitted from the light emitting part (2) and reflected off the diaphragm (1) is received at the light receiving part (3), and a displacement of the diaphragm (1) is converted into an output from the light receiving part (3), a concave diaphragm is used and the concave face is directed toward the light emitting part (2) and the light receiving part (3). According to the arrangement, light emitted from the light emitting part (2) and reflected off the diaphragm (1) impinges efficiently on the light receiving part (3) in the form of focused light.