OPTICAL PICKUP AND OPTICAL INFORMATION PROCESSING DEVICE

• Main Authors: NASUKAWA TOSHIMICHI, HAMANO YUKIKO, HIRAI HIDEAKI, UMEKI KAZUHIRO
• Format: Patent
• Language: English
• Published: 04.12.2008
• Subjects: INFORMATION STORAGE; INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORDCARRIER AND TRANSDUCER; PHYSICS

PROBLEM TO BE SOLVED: To perform aperture switching and aberration correction only with a phase shifter surface to enable reproducing and recording of optical recording media having different substrate thicknesses with the same wavelength luminous flux and a single objective lens. SOLUTION: On the phase shifter surface 502 of a aberration correction means 501, rectangular or step-like differences with different heights in the optical axial direction are formed in a concentric manner around an optical axial center within an area of a region 502a in a region 502b where a light beam passes through. The level differences transmit a light beam having a wavelength of 405 nm directly, and applies a phase difference for correcting spherical aberration of the optical recording medium 117. A light beam that passes through an annular zone region which applies a phase difference that is equal to the integer multiple of 2π to a wavelength among the steps (region where height d of the step is 0 multiple of 2π, which means the region with no level difference) is focused on an optical recording media 107. A light beam that passes through an outside region 502c (flat part) is focused by an object lens 106 on the optical recording medium 107, and is not focused on the optical recording medium 117. The phase shifter surface 502 enables the aberration correction of the optical recording medium 117 and the aperture switching to form a good spot. COPYRIGHT: (C)2009,JPO&INPIT