Patent ID: 11947087
Assignee: TOKYO VISIONARY OPTICS CO., LTD.
Field: Optics (Instruments)
Classification: CPC G | IPC G

Claim 0:
1. An imaging lens comprising in order from an object side to an image side,
a first lens having a convex surface facing the object side and positive refractive power near an optical axis,
a second lens having negative refractive power near the optical axis,
a third lens having aspheric surfaces on both sides,
a fourth lens, and
a fifth lens having a concave surface facing the image side and the negative refractive power near the optical axis, wherein an image-side surface of said fifth lens is formed as an aspheric surface having at least one pole point in a position off the optical axis, and below conditional expressions (1), (2) and (3) are satisfied:

0.70<νd3/νd4<1.30  (1)

0.40<r2/f<1.20  (2)

2.20<r9/f<6.00  (3), where
νd3: an abbe number at d-ray of the third lens,
νd4: an abbe number at d-ray of the fourth lens,
r2: paraxial curvature radius of an image-side surface of the first lens,
r9: paraxial curvature radius of an object-side surface of the fifth lens, and
f: a focal length of the overall optical system of the imaging lens.