Eyepiece
AssigneeNikon Corporation
InventorMasami Arisaka
Life of this patent
Estimating the term…
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.
Claims8
An eyepiece, which has an apparent visual angle of not less than 40.degree., comprising, 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 refractive power;
- and
- a fourth lens group including a single negative lens component,
- wherein at least one surface in said first to fourth lens groups is an aspherical surface whose peripheral portion has a radius of curvature larger than a radius of curvature near a vertex thereof, and
- wherein said aspherical surface satisfies the following formulas:
- ##EQU3## where x is the distance measured from the vertex in an optical axis direction, y is the distance measured from the vertex in a direction perpendicular to the optical axis, C.sub.0 =1/R (radius of curvature at the vertex) is the vertex curvature, .kappa. is a constant of cone, and C.sub.4, C.sub.6, C.sub.8, and C.sub.10 are respectively 4th-, 6th-, 8th-, and 10th-order aspherical surface coefficients.
An eyepiece, which has an apparent visual angle of not less than 40.degree., comprising, 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 refractive power;
- and
- a fourth lens group including a single negative lens component,
- wherein at least one surface of the lens components having positive refractive power in said first to fourth lens groups is an aspherical surface, and said aspherical surface satisfies the following formula:
- 5.times.10.sup.-3 <.vertline.dx/h.vertline.<5.times.10.sup.-2
- where dx is the displacement amount from an incident position of a principal ray with a maximum incident height onto said aspherical surface to an incident position onto an imaginary reference spherical surface, which is measured in the optical axis direction, and h is the distance from the optical axis of the incident position of the principal ray with the maximum incident height.
An eyepiece, which has an apparent visual angle of not less than 40.degree., comprising, 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 refractive power;
- and
- a fourth lens group including a single negative lens component,
- wherein at least one surface of the lens components having a negative refractive power in said first to fourth lens groups is an aspherical surface, and said aspherical surface satisfies the following formula:
- 5.times.10.sup.-4 <.vertline.dx/h.vertline.<5.times.10.sup.-2
- where dx is the displacement amount from an incident position of a principal ray with a maximum incident height onto said aspherical surface to an incident position onto an imaginary reference spherical surface, which is measured in the optical axis direction, and h is the distance from the optical axis of the incident position of the principal ray with the maximum incident height.
An eyepiece lens, which has an apparent visual angle of not less than 40.degree., comprising, 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 refractive power;
- and
- a fourth lens group including a single negative lens component,
- wherein at least one surface in said first to fourth lens groups is an aspherical surface whose peripheral portion has a radius of curvature larger than a radius of curvature near a vertex thereof, and
- wherein at least one of a lens surface on the eyepoint side and a lens surface on the object side of said positive lens component in said second lens group is said aspherical surface, and said aspherical surface satisfies the following formula:
- -1<S.sub.1 <0
- for S.sub.1 =(r.sub.b +r.sub.a)/(r.sub.b -r.sub.a)
- where r.sub.a is the radius of curvature at the vertex of the lens surface on the eyepoint side, and r.sub.b is the radius of curvature at the vertex of the lens surface on the object side.
An eyepiece lens, which has an apparent visual angle of not less than 40.degree., comprising, 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 refractive power;
- and
- a fourth lens group including a single negative lens component,
- wherein at least one surface in said first to fourth lens groups is an aspherical surface whose peripheral portion has a radius of curvature larger than a radius of curvature near a vertex thereof, and
- wherein at least one of a lens surface on the eyepoint side and a lens surface on the object side of said negative lens component in said fourth lens group is said aspherical surface, and said aspherical surface satisfies the following formula:
- -1<S.sub.2 <1
- for S.sub.2 =(r.sub.d +r.sub.c)/(r.sub.d -r.sub.c)
- where r.sub.c is the radius of curvature at the vertex of the lens surface on the eyepoint side, and r.sub.d is the radius of curvature at the vertex of the lens surface on the object side.
Dependencies are inferred from the claim text.