Patent attributes
Wide-angle optical imaging lenses designed to have a wide field of view, stability in optical properties over temperature excursions, and, low chromatic aberrations are described. The lenses are comprised of three lens groups. A first group (counting from the object side) having a negative refractive power comprises two negatively powered elements. The first element has a meniscus shape with a convex object surface. The second lens element has a concave image surface and in preferred embodiments is aspherical. The second group having a positive power comprising two elements. Both elements having positive power. The image surface of the first element in the 2nd group and the object surface of the 2nd element in the 2nd group are both convex. An aperture stop is located between the second and third lens groups. The third lens group has a positive power and includes a cemented doublet or triplet, and a singlet element. Selected lens elements are aspherical and selected lens elements are formed from an optical material having a negative do/dT coefficient.
