Fish-eye lens and imaging device
First Claim
1. A fisheye lens with an angle of incidence of at least 60 degrees, comprising a front group made up of a total of three groups, which are, in order from the object side, two concave lenses whose concave surfaces are directed toward the image side, and a compound lens whose concave surface is directed toward the image side and which has an overall convex or concave refractive power;
- and a rear group formed by three groups of convex lenses, wherein the front group includes at least one compound lens set, the rear group includes only one compound lens set, and at least a first surface of a first concave lens of the front group is an aspheric surface, and satisfies the following conditions;
(1) The aspheric first surface of the first concave lens of the front group either is expressed by the formula X=G(Y), where the origin is the apex of the aspheric surface, X is the optical axis direction, and Y is a direction perpendicular to the optical axis (a positive value), or is expressed as a functional approximation by the formula dx/dY>
0 within the range of Ymax>
Y>
0.5f, where Ymax is the maximum value of the effective radius of the lens, and f is the focal distance of the lens system overall,(2) When the projection function of the lens is taken using h=f*sin ω
as a reference scale, the distortion aberration V when the incidence angle ω
is 60 degrees is such that −
10%≧
V≧
−
16%. Here, V=(H−
h)*100/h (%), and H represents the height of the image from the optical axis when the incidence angle ω
is 60 degrees.
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Accused Products
Abstract
A fisheye lens, comprising a front group made up of a total of three groups, which are two concave lenses 1 and 2 whose concave surfaces are directed toward the image side, and a compound lens 3 whose concave surface is directed toward the image side and which has an overall convex or concave refractive power; and a rear group formed by three groups of convex lenses 4, 5, and 6, wherein the front group includes at least one compound lens set, the rear group includes one compound lens set, and at least a first surface of a first concave lens 1 of the front group is an aspheric surface, and satisfies specific conditions. As a result, it is possible to obtain a fisheye lens that can realize a foveal optical system with undiminished illuminance all the way to the periphery and with high resolution over the entire field of view, and with which a wide field of view and an extremely compact size can be attained with a single wide-angle optical system.
104 Citations
20 Claims
-
1. A fisheye lens with an angle of incidence of at least 60 degrees, comprising a front group made up of a total of three groups, which are, in order from the object side, two concave lenses whose concave surfaces are directed toward the image side, and a compound lens whose concave surface is directed toward the image side and which has an overall convex or concave refractive power;
- and a rear group formed by three groups of convex lenses, wherein the front group includes at least one compound lens set, the rear group includes only one compound lens set, and at least a first surface of a first concave lens of the front group is an aspheric surface, and satisfies the following conditions;
(1) The aspheric first surface of the first concave lens of the front group either is expressed by the formula X=G(Y), where the origin is the apex of the aspheric surface, X is the optical axis direction, and Y is a direction perpendicular to the optical axis (a positive value), or is expressed as a functional approximation by the formula dx/dY>
0 within the range of Ymax>
Y>
0.5f, where Ymax is the maximum value of the effective radius of the lens, and f is the focal distance of the lens system overall,(2) When the projection function of the lens is taken using h=f*sin ω
as a reference scale, the distortion aberration V when the incidence angle ω
is 60 degrees is such that −
10%≧
V≧
−
16%. Here, V=(H−
h)*100/h (%), and H represents the height of the image from the optical axis when the incidence angle ω
is 60 degrees. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
- and a rear group formed by three groups of convex lenses, wherein the front group includes at least one compound lens set, the rear group includes only one compound lens set, and at least a first surface of a first concave lens of the front group is an aspheric surface, and satisfies the following conditions;
-
11. A fisheye lens with an angle of incidence of at least 60 degrees, comprising a front group made up of a total of three groups, which are, in order from the object side, two concave lenses whose concave surfaces are directed toward the image side, and a compound lens whose concave surface is directed toward the image side and which has an overall convex or concave refractive power;
- and a rear group formed by three groups of convex lenses, wherein the front group includes at least one compound lens set, the rear group includes two or more compound lens sets, and at least a first surface of a first concave lens of the front group is an aspheric surface, and satisfies the following conditions;
(6) The aspheric first surface of the first concave lens of the front group either is expressed by the formula X=G(Y), where the origin is the apex of the aspheric surface, X is the optical axis direction, and Y is a direction perpendicular to the optical axis (a positive value), or is expressed as a functional approximation by the formula dx/dY>
0 within the range of Ymax>
Y>
0.5f, where Ymax is the maximum value of the effective radius of the lens, and f is the focal distance of the lens system overall,(7) When the projection function of the lens is taken using h=f*sin ω
as a reference scale, the distortion aberration V when the incidence angle ω
is 60 degrees is such that −
10%≧
V≧
−
16%,here, V=(H−
h)*100/h (%), and H represents the height of the image from the optical axis when the incidence angle ω
is 60 degrees. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19, 20)
- and a rear group formed by three groups of convex lenses, wherein the front group includes at least one compound lens set, the rear group includes two or more compound lens sets, and at least a first surface of a first concave lens of the front group is an aspheric surface, and satisfies the following conditions;
Specification