US Patent 7660049 Optical lens system for taking image

An optical lens system for taking image comprises four lens elements with refractive power, from the object side to the image side: a first meniscus lens element with negative refractive power; a second lens element with positive refractive power having a convex object-side and a convex image-side surface; a third lens element with negative refractive power having a concave object-side surface and a convex image-side surface; a fourth lens element with positive refractive power having a convex object-side surface and a concave image-side surface; and an aperture stop located between the object and the second lens element. The above arrangements effectively reduce the volume of the optical lens system while providing a relatively high resolution.