公开(公告)号：US06266315B1

公开(公告)日：2001-07-24

申请号：US09196111

申请日：1998-11-20

Applicant: Chul-Woo Lee ,  Chong-Sam Chung ,  Yong-Moon Lee ,  Cheol-Sung Yeon ,  Joong-Eon Seo ,  Young-Min Cheong ,  Dong-Ho Shin ,  Kun-Mo Cho ,  Pyong-Yong Seong ,  Jang-Hoon Yoo

Inventor： Chul-Woo Lee ,  Chong-Sam Chung ,  Yong-Moon Lee ,  Cheol-Sung Yeon ,  Joong-Eon Seo ,  Young-Min Cheong ,  Dong-Ho Shin ,  Kun-Mo Cho ,  Pyong-Yong Seong ,  Jang-Hoon Yoo

IPC: G11B700

CPC classification number: G11B7/1387 ,  G11B7/08576 ,  G11B7/0901 ,  G11B7/0908 ,  G11B7/122 ,  G11B7/1374 ,  G11B7/22 ,  G11B7/24 ,  G11B11/10547 ,  G11B11/10554 ,  G11B11/1058 ,  G11B11/10584 ,  G11B2007/13725

Abstract: An optical focusing system which uses a light beam emitted from a light source, includes a refractive surface on one side of the optical focusing system and having a first radius of curvature, a first reflection surface on the above one side, surrounding the refractive surface and having a second radius of curvature being different from the first radius of curvature, a transparent beam focusing surface on the other side of the optical focusing system, and a second reflection surface on the above other side and surrounding the beam focusing surface. The refractive surface refracts an incident light beam, the second reflection surface reflects a light beam refracted by the refractive surface toward the first reflection surface, and the first reflection surface focuses a laser light beam reflected from the second reflection surface on the beam focusing surface as a focused beam spot. The optical focusing system can be used in an optical pickup. The optical pickup uses the optical focusing system to generate, from a light beam e.g. laser light emitted from a light source, a beam spot used for recording or reading information to a recording medium. The optical pickup uses a near field effect provided by an optical focusing system according to the present invention, to allow a superior density of recording or reading. Further, the optical focusing system according to the invention can use a light beam having a beam diameter smaller than that of the laser beam used for an existing optical focusing system for forming a near field. Thus, the optical pickup according to the invention can record or read information on an optical disk having a surface recording density of 10 Gbit/inch2 or more. Even if an incident light beam inclination occurs due to movement of the disk or the optical pickup, information can be recorded on or read from a disk accurately. Also, the assembly of the optical focusing system and the adjustment of the assembled optical focusing system are easily performed.