IMAGING LENS
First Claim
1. An imaging lens for a solid-state image sensor in which lenses are arranged in order from an object side to an image side, comprising:
- an aperture stop;
a first lens with positive refractive power having a convex surface on the object side near an optical axis;
a second lens with positive refractive power having a convex surface on the image side near the optical axis;
a third lens with positive refractive power having a convex surface on the image side near the optical axis; and
a fourth lens with negative refractive power having a concave surface on the image side near the optical axis,wherein all lens surfaces are aspheric;
wherein all the lenses are made of plastic material;
wherein a diffractive optical surface is formed on at least one of lens surfaces from an image-side surface of the first lens to an image-side surface of the second lens; and
wherein at least one of the three lenses with positive refractive power satisfies a conditional expression (1) below;
1.58<
Ndi
(1)whereNdi;
refractive index of the i-th positive lens at d-ray.
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Accused Products
Abstract
An imaging lens includes, from the object side to the image side, an aperture stop, a first lens with positive refractive power having a convex object-side surface near an optical axis, a second lens with positive refractive power having a convex image-side surface near the axis, a third lens with positive refractive power having a convex image-side surface near the axis, and a fourth lens with negative refractive power having a concave image-side surface near the axis, wherein all lens surfaces are aspheric, all lenses are made of plastic material, a diffractive optical surface is formed on at least one of the lens surfaces from the first lens image-side surface to the second lens image-side surface, and at least one of the three positive lenses satisfies expression (1):
1.58<Ndi (1)
- where
- Ndi: refractive index of the i-th positive lens at d-ray.
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Citations
10 Claims
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1. An imaging lens for a solid-state image sensor in which lenses are arranged in order from an object side to an image side, comprising:
-
an aperture stop; a first lens with positive refractive power having a convex surface on the object side near an optical axis; a second lens with positive refractive power having a convex surface on the image side near the optical axis; a third lens with positive refractive power having a convex surface on the image side near the optical axis; and a fourth lens with negative refractive power having a concave surface on the image side near the optical axis, wherein all lens surfaces are aspheric; wherein all the lenses are made of plastic material; wherein a diffractive optical surface is formed on at least one of lens surfaces from an image-side surface of the first lens to an image-side surface of the second lens; and wherein at least one of the three lenses with positive refractive power satisfies a conditional expression (1) below;
1.58<
Ndi
(1)where Ndi;
refractive index of the i-th positive lens at d-ray. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
-
Specification