Patent ID: 7755851

Claim:
A subminiature imaging optical system comprising: first, second, third and fourth lenses sequentially positioned from an object side to an image side, the first lens having positive refractive power, the second lens having negative refractive power, the third lens having negative refractive power, and the fourth lens having positive refractive power, wherein each of the third and fourth lenses has at least one aspherical surface, wherein the first lens has an Abbe number greater than Abbe numbers of the second and third lenses, respectively and the fourth lens has an Abbe number greater than the Abbe numbers of the second and third lenses, respectively, wherein the first to fourth lenses have the Abbe numbers satisfying following conditions 1 to 4, the optical system has an overall size satisfying following condition 5, the first lens has refractive power satisfying following condition 6, the second lens has refractive power satisfying following condition 7, and the third lens has refractive power satisfying following condition 8 , ν 1 ≧50 condition 1, ν 2 ≦40 condition 2, ν 3 ≦40 condition 3, ν 4 ≧50 condition 4, 0.85 <OL/D <1.05 condition 5, F 1 /F≦ 0.68 condition 6, | F 2 /F |≦1.1 condition 7, | F 3 /F 1|>5 condition 8, where ν 1 , ν 2 , ν 3 , and ν 4 are the respective Abbe numbers of the first to fourth lenses, OL is a distance from an object side of the first lens to an image plane, D is an effective optical size of the image plane, F is an effective focal length of a total optical system, F 1 is a focal length of the first lens, F 2 is a focal length of the second lens, and F 3 is a focal length of the third lens.