Endoscope objective lens
AssigneeAsahi Kogaku Kogyo Kabushiki Kaisha
InventorsChikara Yamamoto, Ryota Ogawa
Life of this patent
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Abstract
An endoscope objective lens having a first lens group of negative power, a diaphragm, a second lens group of positive power consisting of first and second lenses, and a third lens group of positive power consisting of a positive lens cemented to a negative lens. The first lens group, diaphragm, first and second lenses of the second lens group, and positive and negative lenses of the third lens group are arranged in this order from an object side. A lens surface on the image side of the first lens has a radius of curvature ri which satisfies the relationship "-0.25.ltoreq.1/ri<0".
Claims14
An endoscope objective lens comprising:
- a first lens group of negative power;
- a diaphragm;
- a second lens group of positive power and consisting of first and second lenses;
- and,
- a third lens group of positive power and consisting of a positive lens cemented to a negative lens;
- wherein said first lens group, said diaphragm, said first and second lenses of said second lens group, and said positive and negative lenses of said third lens group are arranged in this order from an object side to an image side;
- and,
- wherein a lens surface on the image side of said first lens has a radius of curvature ri which satisfies the relationship "-0.25.ltoreq.1/ri<0".
An endoscope objective lens comprising:
- a first lens group of negative power;
- a diaphragm;
- a second lens group of positive power;
- and,
- a third lens group having a positive power, arranged in this order from an object side to an image side, wherein said second lens group consists of a plano-convex lens having a planar surface facing the object side and a positive meniscus lens adhered to the plano-convex lens and having a convex surface facing the image side.
An endoscope objective lens comprising:
- a first lens group made of a single lens of negative power;
- a diaphragm;
- a second lens group of positive power and consisting of a first optical element and a second optical element;
- and,
- a third lens group of positive power and consisting of a positive lens cemented to a negative lens;
- wherein said first lens group, said diaphragm, said first and second optical elements of said second lens group, and said positive and negative lenses of said third lens group are arranged in this order from an object side to an image side;
- and,
- wherein said first and second optical elements are made of glass materials having different Abbe's numbers satisfying the relationship ".nu.2<.nu.3", .nu.2 designating the Abbe's number of the first optical element and .nu.3designating the Abbe's number of the second optical element;
- and,
- further wherein a lens surface on the image side of said first optical element has a radius of curvature ri that satisfies the relationship "-0.25<1/ri<0".
Dependencies are inferred from the claim text.