Olympus Medical Systems Corporation

Akari Kanazawa

Tsutomu Igarashi

Provided is an endoscope objective optical systemincluding, in order from an object side, a first lenscomposed of a negative single lens, a second lenscomposed of a positive single lens, an aperture stop, a third lenscomposed of a positive single lens, and a fourth lenscomposed of a positive combined lens, wherein the third lenshas a meniscus shape having a convex surface facing the image side. The endoscope objective optical system () satisfies the following conditions:0.3&#x3c;&#x3c;1.15,&#x2003;&#x2003;(1)1&#x3c;1.79,&#x2003;&#x2003;(2)2&#x3e;1,&#x2003;&#x2003;(3)0.6&#x3c;&#x3c;0.83,&#x2003;&#x2003;(4) and|1|&#x2212;|2|+1&#x3e;1.8&#x2003;&#x2003;(5)wherein Df is the distance from a surface of the first lens facing the object side to the aperture stop, f is the focal length of the entire system, n1 is the refractive index of the first lens (d-line), n2 is the refractive index of the second lens (d-line), IH is the maximum image height of the entire system, r1 is the radius of curvature of a surface of the third lens facing the object side, r2 is the radius of curvature of the surface of the third lens facing the image side, and d1 is the center thickness of the third lens.

Endoscope objective optical system

An endoscope objective optical system includes, in order from an object side, a first lens composed of a negative single lens, a second lens composed of a positive single lens, an aperture stop, a third lens composed of a positive single lens, and a fourth lens composed of a positive combined lens, the third lens having a meniscus shape having a convex surface facing the image side. The endoscope objective optical system satisfies the following conditions:0.3&#x3c;&#x3c;1.15,&#x2003;&#x2003;(1)1&#x3c;1.79,&#x2003;&#x2003;(2)2&#x3e;1,&#x2003;&#x2003;(3)0.6&#x3c;&#x3c;0.83,&#x2003;&#x2003;(4)and|1|&#x2212;|2|+1&#x3e;1.8&#x2003;&#x2003;(5)Df is the distance from a surface of the first lens facing the object side to the aperture stop, f is the focal length of the entire system, IH is the maximum image height of the entire system, and d1 is the center thickness of the third lens.

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Tokyo, Japan

Akari Kanazawa