US 11,656,437 B2
Optical imaging system including six lenses of −−++−+ refractive powers
Qiqi Lou, Zhejiang Province (CN); Fujian Dai, Zhejiang Province (CN); and Liefeng Zhao, Zhejiang Province (CN)
Assigned to ZHEJIANG SUNNY OPTICAL CO., LTD., Zhejiang Province (CN)
Filed by Zhejiang Sunny Optical Co., Ltd, Zhejiang Province (CN)
Filed on Jul. 28, 2020, as Appl. No. 16/940,551.
Claims priority of application No. 201910740929.0 (CN), filed on Aug. 12, 2019.
Prior Publication US 2021/0048635 A1, Feb. 18, 2021
Int. Cl. G02B 13/00 (2006.01); G02B 9/62 (2006.01); G02B 13/06 (2006.01)
CPC G02B 13/0045 (2013.01) [G02B 9/62 (2013.01); G02B 13/06 (2013.01)] 17 Claims
OG exemplary drawing
 
1. An optical imaging system, consisting of six lenses sequentially from an object side to an image side of the optical imaging system along an optical axis, wherein
the first lens has negative refractive power with a convex object-side surface;
the second lens has negative refractive power;
the third lens has positive refractive power;
the fourth lens has positive refractive power;
the fifth lens has negative refractive power; and
the sixth lens has positive refractive power,
wherein tan(FOV/2)/TTL>1.0 mm−1,
0.9≤CT1/CT4<1.5, and
2.5<f1/f2<8.0,
where FOV is a maximum field-of-view of the optical imaging system, TTL is a distance along the optical axis from the object-side surface of the first lens to an imaging plane of the optical imaging system, CT1 is a center thickness of the first lens along the optical axis, CT4 is a center thickness of the fourth lens along the optical axis, f1 is an effective focal length of the first lens, and f2 is an effective focal length of the second lens
wherein one of following conditions is satisfied,
1.4≤f6/f4<2.5, and
0.8≤SAG22/R4<1.0,
where f4 is an effective focal length of the fourth lens, f6 is an effective focal length of the sixth lens, SAG22 is an on-axis distance from an intersection of an image-side surface of the second lens and the optical axis to a vertex of a maximum effective half-aperture of the image-side surface of the second lens, and R4 is a radius of curvature of the image-side surface of the second lens.