Patent attributes
A lens including a first lens group including three positive singlets and an achromatic doublet for collecting all field rays received at the first lens group while making initial corrections of spherical and color aberrations, a second lens group including a near-symmetrical group including two positive meniscus elements and two negative meniscus elements, wherein the second lens group is configured to correct distortions, a third lens group including two positive lenses with an air gap disposed between the two positive lenses, wherein the third lens group is configured to correct field curvature and astigmatism and a fourth lens group including a triplet and a positive meniscus element, wherein the fourth lens group is configured to correct spherical, coma, axial color and lateral color aberrations, wherein the lens is disposed in an order of the first lens group, the second lens group, the third lens group and the fourth lens group.