Viewfinder optical system
First Claim
1. An eyepiece lens consisting of a single lens element having a positive optical power, said single lens element having a refractive power of an aspherical surface and having a diffractive power,wherein the following condition is fulfilled:
-
space="preserve" listing-type="equation">-0.0006<
{1/(fl·
ν
)}φ
DOE/ν
DOE<
0.0002wherefl represents a focal length resulting from both refractive effect and diffractive effect of the eyepiece lens,ν
represents an Abbe number of the eyepiece lens,φ
DOE represents a power resulting from the diffractive effect of the eyepiece lens, andν
DOE represents an Abbe-number-equivalent value resulting from the diffractive effect of the eyepiece lens.
1 Assignment
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Accused Products
Abstract
An eyepiece lens has a single lens element having a positive optical power, and the single lens element has a refractive power of an aspherical surface and a diffractive power. The eyepiece lens satisfies the following condition:
-0.0006<{1 /(fl·ν)}+φDOE/νDOE<0.0002
where fl represents the focal length resulting from both refractive effect and diffractive effect of the eyepiece lens, ν represents the Abbe number of the eyepiece lens, φDOE represents the power resulting from the diffractive effect of the eyepiece lens, and νDOE represents the Abbe-number-equivalent value resulting from the diffractive effect of the eyepiece lens.
18 Citations
18 Claims
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1. An eyepiece lens consisting of a single lens element having a positive optical power, said single lens element having a refractive power of an aspherical surface and having a diffractive power,
wherein the following condition is fulfilled: -
space="preserve" listing-type="equation">-0.0006<
{1/(fl·
ν
)}φ
DOE/ν
DOE<
0.0002where fl represents a focal length resulting from both refractive effect and diffractive effect of the eyepiece lens, ν
represents an Abbe number of the eyepiece lens,φ
DOE represents a power resulting from the diffractive effect of the eyepiece lens, andν
DOE represents an Abbe-number-equivalent value resulting from the diffractive effect of the eyepiece lens. - View Dependent Claims (2, 3, 4, 5)
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6. An eyepiece lens consisting of a single lens element having a positive optical power, said single lens element having a refractive power of an aspherical surface and having a diffractive power,
wherein the following condition is fulfilled: -
space="preserve" listing-type="equation">-0.0006<
{1/(fl·
ν
)}+φ
DOE/ν
DOE<
0 0002where fl represents a focal length resulting from both refractive effect and diffractive effect of the eyepiece lens, ν
represents an Abbe number of the eyepiece lens,φ
DOE represents a power resulting from the diffractive effect of the eyepiece lens, andν
DOE represents an Abbe-number-equivalent value resulting from the diffractive effect of the eyepiece lens;wherein the eyepiece lens is formed in a meniscus shape.
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7. An eyepiece lens consisting of a single lens element having a positive optical power, said single lens element having a refractive power of an aspherical surface and having a diffractive power,
wherein the following condition is fulfilled: -
space="preserve" listing-type="equation">-0.0006<
{1/(fl·
ν
)}+φ
DOE/ν
DOE<
0.0002where fl represents a focal length resulting from both refractive effect and diffractive effect of the eyepiece lens, ν
represents an Abbe number of the eyepiece lens,φ
DOE represents a power resulting from the diffractive effect of the eyepiece lens, andν
DOE represents an Abbe-number-equivalent value resulting from the diffractive effect of the eyepiece lens;wherein two surfaces of the eyepiece lens each have a diffractive power. - View Dependent Claims (8, 9)
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10. An eyepiece lens consisting of a single lens element having a positive optical power, said single lens element having a refractive power of an aspherical surface and having a diffractive power;
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wherein chromatic aberration resulting from the refractive power of an aspherical surface is substantially canceled by chromatic aberration resulting from the diffractive power; and wherein the following condition is fulfilled;
space="preserve" listing-type="equation">-0.0006<
{1/(fl·
ν
)}+φ
DOE/ν
DOE<
0.0002where fl represents a focal length resulting from both refractive effect and diffractive effect of the eyepiece lens, ν
represents an Abbe number of the eyepiece lens,φ
DOE represents a power resulting from the diffractive effect of the eyepiece lens, andν
DOE represents an Abbe-number-equivalent value resulting from the diffractive effect of the eyepiece lens.
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11. A real-type viewfinder optical system comprising:
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an eyepiece lens system; and an objective lens system; wherein one of said eyepiece lens system and said objective lens system includes a lens element which has a surface having a diffractive power, wherein the following condition is fulfilled;
space="preserve" listing-type="equation">0.01<
|φ
DOE/φ
e|<
0.16where φ
DOE represents a composite power of the surface having a refractive power and a surface having a diffractive power within the lens element, andφ
e represents a composite power of surfaces having refractive powers and surfaces having diffractive powers within said one of said eyepiece lens system and said objective lens system having said lens element therein. - View Dependent Claims (12, 13, 14)
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15. A real-type viewfinder optical system comprising an eyepiece lens system having a lens element which has a surface having a diffractive power,
wherein the following condition is fulfilled: -
space="preserve" listing-type="equation">0.01<
|φ
DOE/φ
e|<
0.16where φ
DOE represents a composite power of the surface having a refractive power and a surface having a diffractive power within the lens element, andφ
e represents a composite power of surfaces having refractive powers and surfaces having diffractive powers within the entire eyepiece lens system;wherein the surface having a diffractive power within the lens element constitutes part of an outer covering of an optical apparatus.
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16. A real-type viewfinder optical system comprising:
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an objective lens; an objective-side inverting prism; and an eyepiece-side inverting prism; wherein; said eyepiece-side inverting prism has a diffractive optical surface formed on a pupil side surface, said pupil side surface of said eyepiece-side inverting prism has a curved surface, and wherein the following condition is fulfilled;
space="preserve" listing-type="equation">0.03<
rE·
φ
D/(1--N)<
0.1where rE represents the radius of curvature of the pupil side surface of the inverting prism, φ
D represents the power of the diffractive optical surface DOE provided on the pupil side surface of the inverting prism, andN represents the refractive index of the inverting prism. - View Dependent Claims (17, 18)
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Specification