US Patent 7785023 Miniature camera lens system

A lens system for a miniature camera includes an imager and four cylindrical lenses disposed concentrically on an optical axis of the lens system. The lenses include, in order from a front end of the lens system to a back end thereof, a first lens, a second lens, a third lens and a fourth lens. 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.