Miniature camera lens system

1. A lens system for a miniature camera, the lens system comprising:

an imager; and,

four cylindrical lenses disposed concentrically on an optical axis of the lens system and including, in order from a front end of the lens system to a back end of the lens system, a first lens, a second lens, a third lens and a fourth lens, wherein:

each of the lenses has opposite front and back surfaces;

the first lens has a positive power and aspheric front and back surfaces;

the second lens has a negative power and aspheric front and back surfaces;

the third lens is made of glass, has a positive power, a plano front surface and a spherical convex back surface; and,

the fourth lens has a negative power and aspheric front and back surfaces.

2. The lens system as recited in claim 1 , wherein the respective diameters of the lenses increase from front to back of the lens system.

3. The lens system as recited in claim 1 , wherein each successive lens has a larger diameter that the preceding lens.

4. The lens system as recited in claim 1 , wherein the lenses are configured such that a first lens and a fourth lens are comprised of the same material such that N 1 =N 4 and v 1 =v 4 .

5. The lens system as recited in claim 1 , wherein the lenses comprise four lenses that are configured such that:

0.2 ≦|N 3 −N 1 |≦0.25;

0.15 ≦|N 3 −N 2 |≦0.19;

0 ≦|N 2 −N 1 |≦0.1;

23 ≦|v 1 −v 2 |≦29;

20 ≦|v 3 −v 2 |≦25;

0 ≦|v 3 −v 1 |≦10; and,

wherein N 1 , N 2 , N 3 and N 4 are the refractive indices at the d line of the first, second, third, and fourth lenses, respectively and v 1 , v 2 , v 3 and v 4 represent the Abbe numbers of the first, second, third, and fourth lenses, respectively.

6. The lens system as recited in claim 1 , wherein the lenses comprise four lenses that are configured such that:

2.5 ≦F/#≦ 4;

0.5 ≦Σd/f≦ 1.1;

0.5 ≦f 1 /f≦ 0.8;

−0.8 ≦f 2 /f≦− 0.6;

0.9 ≦f 3 /f≦ 1.3;

−4.5 ≦f 4 /f≦− 2; and,

wherein F/# is the f-number of the lens system and f 1 , f 2 , f 3 and f 4 represent the effective focal length of a first, second, third, and fourth lens, respectively.

7. The lens system for the miniature camera of claim 1 wherein the imager has a diameter of about 0.25 mm to about 1/3.2 mm.

8. A miniature camera incorporating the lens system of claim 1 .

9. A cellular telephone incorporating the miniature camera of claim 7 .