Patents Represented by Law Firm Shapiro and Shappiro
  • Patent number: 5691850
    Abstract: An eyepiece has an apparent visual angle of 40.degree. or more, and is constituted by, in the following order from the eyepoint side, a first lens group including a cemented lens of negative and positive lens components and having a positive refractive power, a second lens group including a single positive lens component, a third lens group including a cemented lens of positive and negative lens components and having a positive refracting power, and a fourth lens group including a single negative lens component. At least one surface in these lens groups is an aspherical surface, and the fourth-order aspherical surface coefficient of the aspherical surface satisfies .vertline.C.sub.4 .vertline..ltoreq.1.times.10.sup.-3.
    Type: Grant
    Filed: March 17, 1995
    Date of Patent: November 25, 1997
    Assignee: Nikon Corporation
    Inventor: Masami Arisaka