US Patent 10295789 Four-piece optical lens system

A four-piece optical lens system includes, in order from the object side to the image side: a stop, a first lens element with a positive refractive power, a second lens element with a negative refractive power, a third lens element with a positive refractive power, a fourth lens element with a negative refractive power. Such arrangements not only can be applied to a portable electronic product, but also has a long focal length, high pixel and low height.