| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an optical head device and an optical information recording and reproducing apparatus, which can record information and reproduce the recorded information at both of optical recording media of a next generation standard, in which the wavelength of the light source is made shorter, the numerical aperture of the objective lens is made higher, and the thickness of the substrate is made thinner, and conventional recording media of DVD and CD standards. <P>SOLUTION: A light having wavelength of 405 nm, emitted from an optical system 1a, is incident to an objective lens 4a as a collimated light, and is focused on a disk 5a having a substrate thickness of 0.1 mm. A light having wavelength of 650 nm, emitted from an optical system 1b, is incident to the objective lens 4a as a diverging light, and is focused on a disk 5b having a substrate thickness of 0.6 mm. A light having wavelength of 780 nm, emitted from an optical system 1c, is incident to the objective lens 4a as a diverging light, and is focused on a disk 5c having a substrate thickness of 1.2 mm. A spherical aberration, which remains in the light having wavelength of 650 nm or wavelength of 780 nm, is decreased by the change of the magnification of the objective lens 4a, further the decreased spherical aberration is decreased by using a wavelength selective filter 3a. <P>COPYRIGHT: (C)2006,JPO&NCIPI |
