Optical: systems and elements – Lens – Including a nonspherical surface
Reexamination Certificate
2008-03-18
2008-03-18
Sugarman, Scott J. (Department: 2873)
Optical: systems and elements
Lens
Including a nonspherical surface
C359S708000, C359S720000, C369S112010
Reexamination Certificate
active
07345829
ABSTRACT:
Lens aberration in an objective lens for recording and reproducing optical information, which is composed of a molded aspherical single lens, is inhibited while at the same time good lens productivity is attained. Also attained are excellent optical properties and high production efficiency in a mold processing step and a press molding step conducted to manufacture the lens. To this end there is provided an objective lens1having a convex aspherical surface formed at a first surface and a numerical aperture NA which satisfies the condition NA≧0.8. It is preferable to have an aspherical surface also at the second surface. A molding material that was premolded to a prescribed shape and is in a heated and softened state is press molded by using a pair of upper and lower molds having opposing molding surfaces, a molding surface shape is transferred by using a spherical molding material with a radius r and pressing the molding material between a pair of upper and lower molds, and the paraxial curvature radius R of the convex aspherical surface satisfies the following relation r/R≦1.35.
REFERENCES:
patent: 6781764 (2004-08-01), Takeuchi et al.
patent: 6785215 (2004-08-01), Yamanouchi et al.
patent: 6822800 (2004-11-01), Koreeda et al.
patent: 7253968 (2007-08-01), Kimura et al.
patent: 2003/0035225 (2003-02-01), Kim et al.
Koyanagi Hideaki
Terashima Yasutaka
Yamashita Teruo
Yoneda Yasuhiro
Collins Darryl J.
Hoya Corporation
Jordan and Hamburg LLP
Sugarman Scott J.
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