OPTICAL HEAD DEVICE, OPTICAL INFORMATION DEVICE USING SAME, COMPUTER, OPTICAL DISK PLAYER, CAR-NAVIGATION SYSTEM, OPTICAL DISK RECORDER, AND OPTICAL DISK SERVER

PROBLEM TO BE SOLVED: To realize compatible reproduction and recording; among an optical disk (CD) having a substrate material of 1.2 mm in thickness and a corresponding wavelength of λ3 (normally about 790 nm), an optical disk (DVD) having a substrate material of 0.6 mm in thickness and a corresponding wavelength of λ2 (normally about 650 nm) and an optical disk (blue optical disk) having a substrate material of 0.1 mm in thickness and a corresponding wavelength of λ1 (normally about 405 nm); with a high light-utility efficiency by means of a single objective lens. SOLUTION: In an optical head device which executes recording and reproduction by using an objective lens having a large NA, a saw-tooth-shaped hologram is used for recording and reproduction of a conventional optical disk such as a DVD or the like. To blue color, the height of the saw tooth is an optical path length 2λ, and a secondary diffracted ray is used. Red color emits a first diffracted ray. A blaze direction is a convex lens type, and the chromatic aberration of a refractive lens is corrected. A relay lens is arranged between an infrared laser light source and the objective lens. The light beam emitted from the infrared laser light source is condensed by means of the relay lens and then entered into the objective lens again while diffusing. Then, the light beam is condensed on the recording surface of the optical disk as a micro spot by the objective lens through the substrate material of 1.2 mm in thickness. COPYRIGHT: (C)2005,JPO&NCIPI