Title:
ENDOSCOPE OBJECTIVE LENS
Document Type and Number:
Japanese Patent JPH05134171
Kind Code:
A
Abstract:
PURPOSE:To provide an endoscope objective lens which has a small number of lenses, and a short total length, and is low-priced and corrected in aberrations favorably by providing a negative pre-group, a brightness diaphragm and a positive post-group and using a refractive index distribution type lens in the post-group. CONSTITUTION:An endoscope objective lens comprises a pre-group divergent system having negative power, a brightness diaphragm and a post-group convergent system having positive power which are disposed in order from the object side, wherein as at least one lens of the post-group convergent system, when the refractive index distribution is approximated by the expressions (I)-(V), a refractive index distribution lens expressed by the expressions (IV), (VII) is used. In the expressions (I)-(VII), Nd (r), NF (r), NC (r) are refractive index distribution concerning d line, F line C line when the radial distance from the respective optical axes are taken to be (r), N0d-N3d are coefficients of refractive index distribution concerning d line, N0F-N3F are coefficients of refractive index distribution concerning F line, N0C-N3C are coefficients of refractive index distribution concerning C line, and nu0d and nu1d are Abbe numbers expressed in the expressions (IV) and (V) using N0d, N0F, N0C, N1d, N1F, N1C.
Inventors:
KIKUCHI AKIRA
Application Number:
JP29381191A
Publication Date:
May 28, 1993
Filing Date:
October 15, 1991
Export Citation:
Assignee:
OLYMPUS OPTICAL CO
International Classes:
G02B3/00; G02B9/00; G02B9/04; G02B9/12; G02B23/26; (IPC1-7): G02B3/00; G02B9/00; G02B9/04; G02B9/12; G02B23/26
Attorney, Agent or Firm:
Koji Mukai