OPTICAL PICKUP AND OPTICAL INFORMATION PROCESSOR

• Main Authors: HAMANO YUKIKO, HIRAI HIDEAKI
• Format: Patent
• Language: English
• Published: 17.04.2008
• Subjects: INFORMATION STORAGE; INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORDCARRIER AND TRANSDUCER; PHYSICS

PROBLEM TO BE SOLVED: To provide an optical pickup which includes a plurality of light sources corresponding to wavelengths to be used and forms a good spot on any one of recording planes of four types of optical recording media with different substrate thickness using a single objective lens. SOLUTION: A central area 502a of a first diffraction plane 502 corresponds to a NA O.45 of a CD system 137, and transmits a first luminous flux, and diffracts second and third luminous fluxes. A second area 502b corresponds to NA 0.45 to 0.65 of a CD system to DVD system, transmitting the luminous flux, diffracting the second luminous flux, but does not make the CD system condense the third luminous flux. A third area 502c is a flat part corresponding to NA 0.65 to 0.85 of the DVD system to the CD system, transmitting the first to third luminous fluxes, and makes a BD system condense them through the objective lens 106 but does not make the HD, DVD, CD systems condense them. A central area 503a of a second diffraction plane 503 corresponds to a NA 0.65 of the HD system 117, and transmits the first luminous flux to be condensed on the BD system, diffracting the first luminous flux for aberration correction of the HD system, forming a dual focusing lens together with the objective lens 106 to obtain good spots. COPYRIGHT: (C)2008,JPO&INPIT