Optical system with particular optical distortion
View Patent ↗An optical system satisfies conditions related to the optical distortion at the maximum image height and at eighty and sixty percent of the maximum image height in order to reduce the actual observed distortion of an image, for example, an image on a monitor, by balancing the optical distortion with TV distortion. The optical system may be a single focus lens that includes, in order from the object side: a diaphragm stop; and first and second lens components. An aspheric equation that includes a nonzero aspheric coefficient of order three or higher may determine an aspheric shape of a lens surface of the second lens component. Both lens components may be made of plastic.
1. An optical system that satisfies comprising a plurality of lens elements and a stop that form an optical image, said optical system satisfying the following conditions for an image formed by the optical system:
2.0%<|DIST6|<5.0%
| DIST 8 −DIST 6|<0.5%
| DIST 10 −DIST 8|<1.8%
where
DIST6 is the optical distortion of the image at 60% of the maximum image height,
DIST8 is the optical distortion of the image at 80% of the maximum image height, and
DIST10 is the optical distortion of the image at 100% of the maximum image height.
2. The optical system of claim 1 , wherein the lens element on the image side of the optical system includes an aspheric lens surface.
3. The optical system of claim 2 , wherein the shape of the aspheric lens surface is defined by the following equation:
Z=[( C·Y 2 )/{1+(1 −K·C 2 ·Y 2 ) 1/2 }]+Σ(A 1 ·Y i )
where
Z is the length, in millimeters, of a line drawn from a point on the aspheric lens surface at a distance Y from the optical axis to the tangential plane of the aspheric lens surface vertex,
C is the curvature, in millimeters to the minus one power, of the aspheric lens surface on the optical axis,
Y is the distance, in millimeters, from the optical axis,
K is the eccentricity, and
A i is the ith aspheric coefficient, the summation extends over i for i equal to three or greater, and at least one odd-order aspheric coefficient A i of order three or greater is nonzero.
4. The single focus lens of claim 3 , wherein the optical system is a single focus lens that includes at least two lens elements made of plastic.
5. The optical system of claim 1 , wherein the optical system is a single focus lens that includes at least two lens elements made of plastic.
6. The single focus lens of claim 2 , wherein the optical system is a single focus lens that includes at least two lens elements made of plastic.