Title:
VARIABLE POWER LENS
Document Type and Number:
Japanese Patent JPH03158817
Kind Code:
A
Abstract:
PURPOSE:To effectively correct aberration by using an axial type refractive index distribution type lens in a lens system. CONSTITUTION:The lens system is constituted of four lens groups of negative, positive, positive, and positive groups, the lens most close to the image side in the 1st lens group is a refractive index distribution type lens having refractive index distribution satisfying condition (1) on the image side part and the distor tion aberration or the like of the wide side is corrected by the lens concerned. Since the light height of out-of-axis light is high in the 1st lens group, the lens aperture is large and the use of an aspherical surface is not easy, the use of the refractive index distribution type lens is effective. Since a refractive index distribution type lens satisfying condition (3) is used for the most image side lens in the 4th lens group, the spherical aberration, astigmatism and comatic aberration of the wide end are effectively corrected. (1) ¦N1(1).fw¦<0.1 (3) ¦N1(4).fw¦<0.1.
Inventors:
MATSUZAKI HIROSHI
TSUCHIDA HIROBUMI
AOKI NORIHIKO
TSUCHIDA HIROBUMI
AOKI NORIHIKO
Application Number:
JP29762089A
Publication Date:
July 08, 1991
Filing Date:
November 17, 1989
Export Citation:
Assignee:
OLYMPUS OPTICAL CO
International Classes:
G02B9/00; G02B13/18; G02B15/20; (IPC1-7): G02B9/00; G02B13/18; G02B15/20
Attorney, Agent or Firm:
Koji Mukai