US 12,032,145 B2
Imaging optical system, imaging device, and imaging system
Yoshio Matsumura, Osaka (JP); and Hiroyuki Shobayashi, Hyogo (JP)
Assigned to PANASONIC INTELLECTUAL PROPERTY MANAGEMENT CO., LTD., Osaka (JP)
Filed by Panasonic Intellectual Property Management Co., Ltd., Osaka (JP)
Filed on Dec. 10, 2020, as Appl. No. 17/117,658.
Application 17/117,658 is a continuation of application No. PCT/JP2019/023536, filed on Jun. 13, 2019.
Claims priority of application No. 2018-135302 (JP), filed on Jul. 18, 2018.
Prior Publication US 2021/0096346 A1, Apr. 1, 2021
Int. Cl. G02B 13/18 (2006.01); G02B 15/22 (2006.01); G02B 27/00 (2006.01); G02B 27/14 (2006.01); G03B 7/091 (2021.01); G02B 13/00 (2006.01)
CPC G02B 15/22 (2013.01) [G02B 27/0025 (2013.01); G03B 7/091 (2013.01); G02B 13/009 (2013.01)] 15 Claims
OG exemplary drawing
 
1. An imaging optical system having an image circle defined on an imaging element, the imaging optical system comprising:
lens elements arranged from an object side to an image plane side; and
a diaphragm arranged between two of the lens elements that are adjacent to each other,
wherein:
the lens elements include freeform lens elements, each having a freeform surface that is an asymmetrical surface with respect to a first cross section and a second cross section, the first cross section being defined by a first direction and an optical axis direction, the second cross section being defined by a second direction and the optical axis direction, the first direction crossing the second direction, and the optical axis direction being orthogonal to the first direction and the second direction;
at least two of the freeform lens elements are located on an object side of the diaphragm;
the image circle has a first diameter in the first direction and a second diameter in the second direction, the first diameter being equal to or larger than the second diameter;
the imaging optical system satisfies a following conditional expression (1) based on a summation for the freeform surfaces of the at least two of the freeform lens elements located on the object side of the diaphragm:

OG Complex Work Unit Math
N is a total number of the freeform surfaces of the at least two of the freeform lens elements located on the object side of the diaphragm;
k is a number identifying a k-th freeform surface of the total number of the freeform surfaces of the at least two of the freeform lens elements located on the object side of the diaphragm;
SLk is a sag amount at a first position where a first height of the k-th freeform surface in the first direction is 50% of a shortest image height among the image circle;
SSk is a sag amount at a second position where a second height of the k-th freeform surface in the second direction is 50% of the shortest image height among the image circle;
Δndk is a difference resulting from subtracting a refractive index on an object side of the k-th freeform surface from a refractive index on an image plane side of the k-th freeform surface; and
YSH is a height of 50% of the shortest image height among the image circle.