US 11,668,897 B2
Imaging lens
Yukio Sekine, Tokyo (JP); and Kenichi Kamada, Tokyo (JP)
Assigned to TOKYO VISIONARY OPTICS CO., LTD., Tokyo (JP)
Filed by TOKYO VISIONARY OPTICS CO., LTD., Tokyo (JP)
Filed on Sep. 10, 2020, as Appl. No. 17/17,326.
Claims priority of application No. JP2019-128345 (JP), filed on Jul. 10, 2019.
Prior Publication US 2021/0231922 A1, Jul. 29, 2021
Int. Cl. G02B 9/60 (2006.01); G02B 13/00 (2006.01); G02B 27/00 (2006.01)
CPC G02B 9/60 (2013.01) [G02B 13/0045 (2013.01); G02B 27/0025 (2013.01)] 6 Claims
OG exemplary drawing
 
1. An imaging lens comprising, in order from an object side to an image side:
a first lens with positive refractive power having a convex object-side surface in a paraxial region,
a second lens with negative refractive power in a paraxial region,
a third lens with negative refractive power in a paraxial region,
a fourth lens with positive refractive power in a paraxial region, and
a fifth lens with negative refractive power having a convex image-side surface in a paraxial region, wherein the following conditional expressions (1), (2), (3) and (8) are satisfied:
48.00<νd3<70.00  (1)
0.20<|r2|/f<8.00  (2)
−2.30<|r2|/r3/r10<−0.45  (3)
0.05<D3/T3<0.25  (8)
where
νd3: an abbe number at d-ray of the third lens,
f: a focal length of an overall optical system of the imaging lens,
r2: a paraxial curvature radius of an image-side surface of the first lens,
r3: a paraxial curvature radius of an object-side surface of the second lens,
r10: a paraxial curvature radius of an image-side surface of the fifth lens,
D3: a thickness along the optical axis of the third lens, and
T3: a distance along the optical axis from an image-side surface of the third lens to an object-side surface of the fourth lens.