Hoya Corporation

Sachiko Nasu

Hiroaki Fujii

The objective lens unit includes, a front lens group having a negative refractive power, a diaphragm, and a rear lens group having a positive refractive power, in order from an object side. The front lens group includes a negative lens having a concave surface facing an image surface side, and a positive lens having a convex surface facing the object side, and the rear lens group includes a positive lens having a convex surface facing the image surface side and a cemented lens in which a positive lens and a negative lens are cemented. The endoscope objective lens unit satisfies &#x2212;1.6&#x3c;f/f&#x3c;&#x2212;1.2 and &#x2212;1.0&#x3c;SF&#x3c;&#x2212;0.5. fand fare the focal lengths of the front lens group and the rear lens group, SFis (R+R)/(R&#x2212;R), and Rand Rare respectively the curvature radiuses of surfaces.

Endoscope objective lens unit and endoscope

The objective lens unit includes, a front lens group having a negative refractive power, a diaphragm, and a rear lens group having a positive refractive power, in order from an object side. The front lens group includes a negative lens having a concave surface facing an image surface side, and a positive lens having a convex surface facing the object side, and the rear lens group includes a positive lens having a convex surface facing the image surface side and a cemented lens in which a positive lens and a negative lens are cemented. The endoscope objective lens unit satisfies &#x2212;1.6&#x3c;f/f&#x3c;&#x2212;1.2 and &#x2212;1.3&#x3c;f/f&#x3c;&#x2212;0.7. Note that fand fare focal lengths of the entire system of the front lens group and the rear lens group, and fis a focal length of a positive lens, in the rear lens group.

An endoscope magnification optical system includes, in order from an object side, a first lens group having a negative power, a second lens group having a positive power, and a third lens group having a meniscus lens with a convex surface facing the object side. A distance from a lens surface of the first lens group that is nearest to the object side to an image surface is kept constant while the second lens group is moved in an optical axis direction with respect to the first lens group and the third lens group, which are fixed lens groups, and thereby an optical image is magnified.

Endoscope magnification optical system, endoscope, and endoscope system

A light source optical system includes a light source, an optical system that collects light incident from the light source; and a light guide rod having a reflecting inner surface for guiding light received through an entrance port to an exit port by total internal reflection, the reflecting inner surface being gradually tapered, towards a light guide axis in the direction of the exit port, in one of an entire region defined from the entrance port to the exit port, and a region defined from a midway point between the entrance port and the exit port to the exit port.

Light source optical system having tapered light guide rod

A variable power optical system for an endoscope comprising a first lens group having a negative power, a second lens group having a positive power and a third lens group, and wherein the first lens group includes at least a negative lens having a concave surface pointing to an image side and a positive meniscus lens having a concave surface pointing to an object side, the second lens group includes at least a meniscus lens having a convex surface pointing to the object side and a cemented lens formed by cementing together a negative lens and a positive lens, and the third lens group includes at least a positive lens having a convex surface pointing to the object side, and wherein the variable power optical system for an endoscope is configured to satisfy a predetermined condition.

Endoscope and variable power optical system for the same

An objective lens for an endoscope, including a negative front lens group and a positive rear lens group arranged such that an aperture stop is positioned therebetween, wherein the front lens group has at least a front-side negative lens and a front-side positive lens arranged in this order from an object side, and the rear lens group has at least a rear-side positive lens and a cemented lens arranged in this order from the object side, the cemented lens being configured by cementing together negative and positive lenses. The objective lens satisfies following conditions: &#x2212;4.5&#x2266;f/f&#x2266;&#x2212;2.0 and 1.5&#x2266;f/f&#x2266;2.5, where f(unit: mm) represent of the front lens group, f (unit: mm) represents a total focal length of the front lens group and the rear lens group, and f(unit: mm) represents a focal length of the rear-side positive lens.

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Tokyo, Japan

Sachiko Nasu