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1. (WO2018203465) OBJECTIVE OPTICAL SYSTEM

Pub. No.:    WO/2018/203465    International Application No.:    PCT/JP2018/015169
Publication Date: Fri Nov 09 00:59:59 CET 2018 International Filing Date: Thu Apr 12 01:59:59 CEST 2018
IPC: G02B 13/04
Applicants: OLYMPUS CORPORATION
オリンパス株式会社
Inventors: TAKATO Hideyasu
高頭英泰
Title: OBJECTIVE OPTICAL SYSTEM
Abstract:
Provided is an objective optical system that is not readily affected by various errors and that is bright, and whereby various aberrations are satisfactorily corrected. An objective optical system has, in order from the object side thereof, a first lens group G1 having a negative refractive power, a second lens group G2 having a positive refractive power, a third lens group G3 having a negative refractive power, and a fourth lens group G4 having a positive refractive power, the second lens group G2 moving toward the object side and the third lens group G3 moving toward the image side during focusing from a distant object point to a close object point, and conditional expression (1) being satisfied. (1) 2 < fG2/f < 8. In the expression, fG2 is the focal length of the second lens group, and f is the focal length of the objective optical system overall when focused at the distant object point.