| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a phase correction element which can deal with recording and/or reproducing of information of three kinds of optical disks; an HD (Hard Disk), DVD (Digital Versatile Disk) and CD (Compact Disk) by using a single objective lens for the HD. <P>SOLUTION: The phase correction element 10 is constituted by forming a phase correction layer 10A consisting of rugged parts which have rotational symmetry with respect to the optical axis of incident light in a region of a numerical aperture NA<SB>2</SB>and in which the sectional shapes are serrated or the respective projecting parts of the serrations are approximated by staircase shapes and by integrating the same with a first phase plate 30A which generates a birefringent phase difference of odd times approximately π/2 the linearly polarized light of a wavelength λ<SB>1</SB>. The element has a function to make the transmission wave surface of the wavelength λ<SB>1</SB>invariable to incident light of three wavelenrths; λ<SB>1</SB>=410 wavelength band, λ<SB>2</SB>=650 wavelength band, and λ<SB>3</SB>=780 wavelength band, and to change the transmision wave surface of the wavelength λ<SB>2</SB>or the transmision wave surfaces of the wavelength λ<SB>2</SB>and the wavelength λ<SB>3</SB>. <P>COPYRIGHT: (C)2004,JPO&NCIPI |
