Title:
VARIABLE POWER OPTICAL SYSTEM FOR ENDOSCOPE AND ENDOSCOPE
Document Type and Number:
WIPO Patent Application WO/2019/163744
Kind Code:
A1
Abstract:
A variable power optical system for an endoscope is provided with, in order from an object, a first lens group having a negative power and a second lens group having a positive power and capable of moving along the optical axis. The first lens group includes a negative lens with the concave surface facing an image and a positive lens with the convex surface facing the object in order from the object, and the second lens group includes a cemented lens bonded to a positive lens with the convex surface facing the object. The variable power optical system for an endoscope satisfies the following expressions:
0.6 < |fs1 / f1| < 1.6,
1.2 < ft / fw < 1.4, and
0.5 < |f2 / f1| < 0.8
where f1 [mm] and f2 [mm] represent synthetic focal lengths of the first and second lens groups, respectively; fw [mm] represents a synthetic focal length for the entire system when observing a distant object; ft [mm] represents a synthetic focal length for the entire system when observing an enlarged object; and fs1 represents a focal length of the positive lens closest to the image in the first lens group.
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Inventors:
NASU SACHIKO (JP)
Application Number:
PCT/JP2019/006027
Publication Date:
August 29, 2019
Filing Date:
February 19, 2019
Export Citation:
Assignee:
HOYA CORP (JP)
International Classes:
A61B1/00; G02B13/04; G02B15/16; G02B15/163; G02B23/26
Domestic Patent References:
| WO2017043352A1 | 2017-03-16 |
Foreign References:
| JP2016161628A | 2016-09-05 | |||
| JP2015215406A | 2015-12-03 | |||
| JPS6287926A | 1987-04-22 | |||
| JPH0519169A | 1993-01-29 | |||
| JPH09152552A | 1997-06-10 | |||
| JP2011247922A | 2011-12-08 | |||
| JPH103038A | 1998-01-06 |
Attorney, Agent or Firm:
GLOBAL IP TOKYO (JP)
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