Title:
ENDOSCOPIC OPTICAL SYSTEM
Document Type and Number:
WIPO Patent Application WO/2019/220730
Kind Code:
A1
Abstract:
The purpose of the present invention is to provide an endoscopic optical system which has favorably corrected chromatic aberration and is able to prevent lens shift due to a small shock. This endoscopic optical system comprises, in order from the object side, a fixed negative first lens group G1, a movable positive second lens group G2, a fixed aperture stop S, and a fixed positive third lens group G3, and is switchable between a normal observation state and an enlarged observation state by moving the second lens group G2 along an optical axis AX. The third lens group G3 comprises, in order from the object side, a three-lens cemented lens CL1 obtained by cementing three lenses of a positive lens L5, a negative lens L6, and a positive lens L7, and a two-lens cemented lens CL2 obtained by cementing two lenses of a positive lens L8 and a negative lens L9, and the following conditional expressions (1), (2) are satisfied: 1.70<(nd3G1+nd3G2+nd3G3)/3<2.0 … (1) and 1.72<(nd3G4+nd3G5)/2<2.0 … (2).
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Inventors:
KATAKURA MASAHIRO (JP)
Application Number:
PCT/JP2019/006760
Publication Date:
November 21, 2019
Filing Date:
February 22, 2019
Export Citation:
Assignee:
OLYMPUS CORP (JP)
International Classes:
G02B13/04; A61B1/00; G02B15/15; G02B23/26
Domestic Patent References:
| WO2018008460A1 | 2018-01-11 | |||
| WO2017183371A1 | 2017-10-26 |
Foreign References:
| JPH1073758A | 1998-03-17 | |||
| JP2012063756A | 2012-03-29 | |||
| JP2011227351A | 2011-11-10 |
Attorney, Agent or Firm:
SAITO Keisuke (JP)
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