US 7,551,539 B2
Optical element, aberration correcting element, light converging element, objective optical system, optical pickup device, and optical information recording reproducing device
Tohru Kimura, Hachioji (Japan); Kiyoshi Yamashita, Hachioji (Japan); Nobuyoshi Mori, Hachioji (Japan); and Yuichi Atarashi, Hachioji (Japan)
Assigned to Konica Minolta Opto, Inc., Tokyo (Japan)
Filed on Feb. 26, 2008, as Appl. No. 12/71,740.
Application 12/071740 is a division of application No. 10/866902, filed on Jun. 15, 2004, granted, now 7,369,481.
Claims priority of application No. 2003-173911 (JP), filed on Jun. 18, 2003; application No. 2003-296556 (JP), filed on Aug. 20, 2003; application No. 2003-318483 (JP), filed on Sep. 10, 2003; application No. 2003-385393 (JP), filed on Nov. 14, 2003; application No. 2003-435248 (JP), filed on Dec. 26, 2003; and application No. 2004-110368 (JP), filed on Apr. 02, 2004.
Prior Publication US 2008/0170487 A1, Jul. 17, 2008
Int. Cl. G11B 7/00 (2006.01)
U.S. Cl. 369—112.07  [369/112.12] 35 Claims
OG exemplary drawing
 
1. An optical system for use in an optical pickup apparatus in which reproducing and/or recording information is conducted for a first optical information recording medium equipped with a protective layer having a thickness t1 by using a light flux having a first wavelength λ1 emitted from a first light source and reproducing and/or recording information is conducted for a second optical information recording medium equipped with a protective layer having a thickness t2 (t2≧t1) by using a light flux having a second wavelength λ2 (λ2>λ1) emitted from a second light source, comprising:
a correcting optical system;
a light converging element to converge a light flux having a wavelength λ1 emitted from the correcting optical system on an information recording plane of the first optical information recording medium and to converge a light flux having a wavelength λ2 emitted from the correcting optical system on an information recording plane of the second optical information recording medium;
wherein an optical surface of the correcting optical system has a plurality of optical functional zones, and a superposition type diffractive structure is formed within one of the plurality of optical functional zones such that a plurality of ring-shaped zones are formed concentrically around the optical axis and plural stepped sections shaped stepwise are formed within each ring-shaped zone.