Title:
OBSERVATION OPTICAL SYSTEM FOR ENDOSCOPE
Document Type and Number:
Japanese Patent JPH05288986
Kind Code:
A
Abstract:
PURPOSE:To make a wide-angle endoscope observation while a distortion aberration is excellently compensated by arranging at least an object-side observation aperture in liquid and satisfying specific conditions. CONSTITUTION:When an object in optional liquid is observed, an image having its distortion aberration excellently compensated is obtained. In this case, at least the observation aperture of the object is arranged in the liquid and the conditions shown by expressions are satisfied. Here, Nw is the refractive index of the liquid, (f) the focal length of an objective optical system, thetaA1 the field angle in air at maximum image height, thetaA0.5 the field angle in air at image height a half as high as the maximum image height, II the maximum image height, and I0.5 the image height a half as high as the maximum image height. In this case, a sapphire material is used for the concave lens which is arranged most on the object side to increase durability to high-temperature and high- pressure steam in bacillus reduction, and the need to put cover glass in the optical path between the objective optical system and body is eliminated.
Inventors:
KIKUCHI AKIRA
TSUYUKI HIROSHI
TSUYUKI HIROSHI
Application Number:
JP11667392A
Publication Date:
November 05, 1993
Filing Date:
April 10, 1992
Export Citation:
Assignee:
OLYMPUS OPTICAL CO
International Classes:
G02B13/04; G02B13/18; G02B23/26; (IPC1-7): G02B13/04; G02B13/18; G02B23/26
Attorney, Agent or Firm:
Koji Mukai