Image lens with high resolution, low chromatic aberration, and long flange back distance

An image lens for imaging an object on an image plane, in the order from the object side to the image side thereof, comprising:

• a first lens having positive refraction power and comprising a first surface facing the object side and a second surface facing the image side;
• and
• a second lens having negative refraction power and comprising a third surface facing the object side and a fourth surface facing the image side;
• wherein the image lens satisfies the following formulas:
• FB/TTL>0.38;
• (1)
• R11/F1>2.23;
• (2)
• Z/Y>0.11;
• (3)
• Z/T<0.42;
• (4)
• R23/F2<R12/F2<R24/F2;
• (5)
• wherein FB is a distance between the fourth surface and the image plane along an optical axis of the image lens, TTL is a total length of the image lens, Z is a distance from a central point of the fourth surface to an outer edge of the fourth surface along the optical axis of the image lens, Y is a distance from the central point of the fourth surface to the outer edge of the fourth surface along a direction perpendicular to the optical axis of the image lens, T is a thickness of the second lens on the optical axis, R23 is a curvature radius of the third surface, R24 is a curvature radius of the fourth surface, R11 is a curvature radius of the first surface;
• R12 is a curvature radius of the second surface, and F2 is a focal length of the second lens.