Objective lens system for endoscopes having an image transfer optical fiber bundle
First Claim
1. An objective lens system for an endoscope having an image transfer optical fiber bundle, which comprises from the object end to the image end a negative powered first lens element L1 having a concave image side surface, a positive powered second lens element L2 having a radius of curvature greater on an image side than on an object side, a positive powered third lens element L3 having a radius of curvature greater on the object side than on the image side, a positive powered doublet lens component comprising fourth lens element L4 and fifth lens element L5, and an aperture diaphragm interposed between the second lens element and the third lens element, said objective lens system satisfying the following relations:
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space="preserve" listing-type="equation">|d·
f/f.sub.R.sup.2 |<
0.11
space="preserve" listing-type="equation">v2<
45.0where f is the equivalent focal length of the entire objective lens system, fR is the equivalent focal length of the rear lens group including the third, fourth and fifth lens elements;
d is the axial distance between the aperture diaphragm and the front focal point of the rear lens group, and v2 is the Abbe number of glass for the second lens element.
1 Assignment
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Accused Products
Abstract
An objective lens system for an endoscope having an image transfer optical fiber bundle comprises from the object end a first lens of negative power having a concave image side surface, a second lens of positive power having a radius of curvature greater on an image side than on an object side, a third lens of positive power having a radius of curvature greater on the object side than on the image side, a doublet lens of positive power which comprises a forth lens element and a fifth lens element, and an aperture diaphragm interposed between the second and third lenses and satisfies the following relations:
|d·f/f.sub.R.sup.2 |<0.11
v2<45.0
where f is the equivalent focal length of the entire objective lens system, fR is the equivalent focal length of the rear lens group including the third, fourth and fifth lens elements, d is the axial distance between the aperture diaphragm and the front focal point of the rear lens group, and v2 is the Abbe number of glass for the second lens.
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Citations
8 Claims
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1. An objective lens system for an endoscope having an image transfer optical fiber bundle, which comprises from the object end to the image end a negative powered first lens element L1 having a concave image side surface, a positive powered second lens element L2 having a radius of curvature greater on an image side than on an object side, a positive powered third lens element L3 having a radius of curvature greater on the object side than on the image side, a positive powered doublet lens component comprising fourth lens element L4 and fifth lens element L5, and an aperture diaphragm interposed between the second lens element and the third lens element, said objective lens system satisfying the following relations:
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space="preserve" listing-type="equation">|d·
f/f.sub.R.sup.2 |<
0.11
space="preserve" listing-type="equation">v2<
45.0where f is the equivalent focal length of the entire objective lens system, fR is the equivalent focal length of the rear lens group including the third, fourth and fifth lens elements;
d is the axial distance between the aperture diaphragm and the front focal point of the rear lens group, and v2 is the Abbe number of glass for the second lens element. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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Specification