ApplicationNo. 321683 filed on 03/10/1989
US Classes:359/708, Including a nonspherical surface359/770, First component negative359/781First component negative
ExaminersPrimary: Bovernick, Rodney B.
Assistant: Gass, Rebecca D.
Attorney, Agent or Firm
Foreign Patent References
International ClassesG02B 009/34
Foreign Application Priority Data1988-03-11 JP
AbstractA first lens, a second lens, means and a third lens means are arranged successively in a direction of travel of a ray. The first lens means each comprising a single lens element power. The second lens means has a predetermined negative refracting power. The third lens means has a predetermined positive refracting power. A fourth lens means consisting of a plurality of lens elements follows the third lens means in the direction of travel of the ray and has a predetermined positive refracting power. At least one surface of the first, second, third, and fourth lens elements is aspherical. The follwoing conditions (1), (2), and (3) are satisfied:4f<f3<20f (1)0.65<(f4/d34)<1.40 (2)10f<R5 (3)where the character "f" denotes a focal length of the optical projection system, the character "f3"denotes a focal length of the third lens means, the character "f4" denotes a focal length of the lens group, the character "d34" denotes a distance between a rear principal point of the third lens means and a front principal point of the fourth lens, and the character "R5" denotes a radius of curvature of a front surface of the third lens means.