US 12,345,863 B2
Optical system, optical apparatus and method for manufacturing the optical system
Fumiaki Ohtake, Tokyo (JP)
Assigned to Nikon Corporation, Tokyo (JP)
Appl. No. 17/783,632
Filed by Nikon Corporation, Tokyo (JP)
PCT Filed Nov. 17, 2020, PCT No. PCT/JP2020/042794
§ 371(c)(1), (2) Date Jun. 8, 2022,
PCT Pub. No. WO2021/117429, PCT Pub. Date Jun. 17, 2021.
Claims priority of application No. 2019-223170 (JP), filed on Dec. 10, 2019.
Prior Publication US 2023/0023567 A1, Jan. 26, 2023
Int. Cl. G02B 15/177 (2006.01); B29D 11/00 (2006.01); G02B 15/14 (2006.01)
CPC G02B 15/177 (2013.01) [B29D 11/00009 (2013.01); G02B 15/145507 (2019.08)] 28 Claims
OG exemplary drawing
 
1. An optical system consisting of a preceding lens group having a negative refractive power and a succeeding lens group having a positive refractive power which are arranged in order from an object side along an optical axis,
wherein the succeeding lens group comprises a focusing group having a positive refractive power which is arranged to be closest to an object in the succeeding lens group, and an image-side group which is arranged to be closer to an image than the focusing group, and the focusing group moves to an image side along the optical axis upon focusing on a short-distance object from an object at infinity, and
the following conditional expressions are satisfied:
0.78<fB/fC<1.00
1.20<FNO<3.00
where
fB: a focal length of the succeeding lens group upon focusing on infinity,
fC: a focal length of the image-side group upon focusing on infinity, and
FNO: F number of the optical system upon focusing on infinity.