Patent ID: 8547648

Claim:
A lens module, comprising: a first lens, disposed between an object side and an image side, wherein a first surface of the first lens facing the object side is an aspheric surface, and a curvature radius of the first surface is R 1 ; a second lens, disposed between the first lens and the image side, wherein a second surface of the second lens facing the image side is an aspheric surface, and a curvature radius of the second surface is R 2 ; a light transmissive device, wherein the first lens and the second lens are respectively leaned against two opposite sides of the light transmissive device; and an aperture stop, disposed between the first lens and the second lens, wherein a distance from the first surface to the aperture stop is dl, and a distance from the second surface to the aperture stop is d 2 , wherein the lens module satisfies 6>d 2 /d 1 >2.5 and −2.5<R 1 /R 2 <1.5, an effective focal length (EFL) of the lens module is f, and the lens module satisfies 0.8<f<1.6, and a material refractive index of the first lens and the second lens is n d , and 1.62>n d >1.48, wherein the first surface and the second surface are even aspheric surfaces, and which are respectively expressed as: Z = cr 2 1 + 1 - ( 1 + k ) ⁢ c 2 ⁢ r 2 + α 1 ⁢ r 2 + a 2 ⁢ r 4 + α 3 ⁢ r 6 + α 4 ⁢ r 8 + α 5 ⁢ r 10 + α 6 ⁢ r 12 + α 7 ⁢ r 14 + α 8 ⁢ r 16 . wherein α 1 to α 8 are aspheric coefficients, and the first surface and the second surface satisfy α 1 =0.