Abstract: An objective optical system for endoscope includes a first group having a negative refractive power, an aperture stop, and a second group having a positive refractive power. The first group includes a negative meniscus lens having a convex surface directed toward the object side, and a positive lens having a convex surface directed toward the object side. The second group includes a predetermined lens, a positive cemented lens, and a positive single lens, or includes the predetermined lens, the positive single lens, and a positive cemented lens. The predetermined lens is a meniscus lens having a convex surface directed toward an image side. and an image-side lens, and the following conditional expressions (1?), (2), and (4?) are satisfied: 0.7<|R1/R2|<1.1??(1?), 0.6<|R1/FL|<3??(2), and 5?|Fc/FL|?7??(4?).

Abstract: An image-acquisition apparatus includes an objective lens consisting of, in order from an object side, a first group and a second group, an image-acquisition device that converts an optical image of an object formed by the objective lens into an electrical signal, a first holding frame holding the first group of the objective lens inside, and a second holding frame holding the second group of the objective lens and the image-acquisition device inside. The objective lens satisfies specific conditions.

Abstract: An objective optical system for endoscope includes a first group having a negative refractive power, an aperture stop, and a second group having a positive refractive power. The first group includes a negative meniscus lens having a convex surface directed toward the object side, and a positive lens having a convex surface directed toward the object side. The second group includes a predetermined lens, a positive cemented lens, and a positive single lens, or includes the predetermined lens, the positive single lens, and a positive cemented lens. The predetermined lens is a meniscus lens having a convex surface directed toward an image side. and an image-side lens, and the following conditional expressions (1?), (2), and (4?) are satisfied: 0.7<|R1/R2|<1.1??(1?), 0.6<|R1/FL|<3??(2), and 5?|Fc/FL|?7??(4?).

Abstract: An imaging unit includes: a columnar optical member including an incident surface on which light is incident, a reflecting surface for reflecting the light incident from the incident surface in a direction different from the incident surface, and an emission surface for causing the light incident from a direction orthogonal to the incident surface and reflected from the reflecting surface to travel in a straight line and emitting the light to the outside; an imaging device including a light receiving unit, formed on a surface of the imaging device, for receiving the light emitted from the emission surface and performing photoelectric conversion on the light; and a cylindrical imaging holder, protruding from at least part of an outer edge of one end in line with a side surface shape of the optical member, for defining the position of the incident surface and holding the optical member.

Abstract: This endoscope imaging device is to improve focus adjustment accuracy between an imaging element and an objective lens. This endoscope imaging device has an objective lens unit frame holding objective lenses, and an imaging element supporting frame fitted onto an outer side of the objective lens unit and holding an imaging element. The lateral cross-sectional shape of a fitted portion of an outer surface of the objective lens unit frame and the lateral cross-sectional shape of a fitted portion of an inner surface of the imaging element supporting frame are different, and in the fitted portions, a contact portion where said two frames come into contact, and a gap portion where said two frames do not come into contact are formed, and also the objective lens unit frame and the imaging element supporting frame are cemented by a photosetting glue filled in the gap portion.

Abstract: An image-acquisition apparatus includes an objective lens consisting of, in order from an object side, a first group and a second group, an image-acquisition device that converts an optical image of an object formed by the objective lens into an electrical signal, a first holding frame holding the first group of the objective lens inside, and a second holding frame holding the second group of the objective lens and the image-acquisition device inside. The objective lens satisfies conditions (1) and (2): ?2.871<f_front/f<?1.180??(1) ?1.498<f_front/f_rear<?0.607??(2) where f_front is a focal length of the first group, f_rear is a focal length of the second group, and f is a focal length of the entire objective lens.

Abstract: Manufacturing errors are suppressed, and the precision of positioning between an image-acquisition device and an objective lens is improved.

Abstract: Positioning precision between an image-acquisition device and an objective lens is enhanced by suppressing manufacturing errors. Provided is an endoscope image-acquisition unit equipped with an objective-lens-unit frame that holds an objective lens and an image-acquisition-device holding frame that is fitted to the objective-lens-unit frame and that holds an image-acquisition device, wherein the objective-lens-unit frame and the image-acquisition-device holding frame are attached and secured to each other by means of thermosetting resin that is applied to fitting portions therebetween and in which polar-molecule materials are mixed, and one of the objective-lens-unit frame and the image-acquisition-device holding frame, whichever one is positioned outside at the fitting portions, is formed of a material that allows microwaves to pass therethrough.

Abstract: An object is to provide an endoscope objective lens in which the aberrations are less susceptible to manufacturing errors and in which the variation in field curvature caused by focusing is small. There is provided an endoscope objective lens including: in sequence from an object side, a front group having negative refractive power, an aperture stop, and a rear group having positive refractive power; and a focusing lens that has a negative refractive power and that can be inserted into an optical path between the front group and the rear group. The focusing lens is inserted into the optical path in a normal observation state and is retracted from the optical path in a short-distance observation state, in which the working distance is smaller than that in the normal observation state.

Abstract: Positioning precision between an image-acquisition device and an objective lens is enhanced by suppressing manufacturing errors. Provided is an endoscope image-acquisition unit equipped with an objective-lens-unit frame that holds an objective lens and an image-acquisition-device holding frame that is fitted to the objective-lens-unit frame and that holds an image-acquisition device, wherein the objective-lens-unit frame and the image-acquisition-device holding frame are attached and secured to each other by means of thermosetting resin that is applied to fitting portions therebetween and in which polar-molecule materials are mixed, and one of the objective-lens-unit frame and the image-acquisition-device holding frame, whichever one is positioned outside at the fitting portions, is formed of a material that allows microwaves to pass therethrough.

Abstract: The depth of field is extended by using a simple structure. Provided is an imaging device comprising: an objective optical system that comprises an aperture stop that is disposed at an intermediate position on an optical axis and that has an opening that allows incident light from an object to pass therethrough; and an imaging element that acquires an optical image of the object, which is formed by the objective optical system, wherein pixels of the imaging element are arranged in a square along two mutually orthogonal axial directions, and the aperture stop includes a light-blocking portion at a portion aligned with the optical axis, the light-blocking portion having a square shape with sides inclined at 45° relative to the directions in which the pixels are arranged.

Abstract: An imaging unit includes: a columnar optical member including an incident surface on which light is incident, a reflecting surface for reflecting the light incident from the incident surface in a direction different from the incident surface, and an emission surface for causing the light incident from a direction orthogonal to the incident surface and reflected from the reflecting surface to travel in a straight line and emitting the light to the outside; an imaging device including a light receiving unit, formed on a surface of the imaging device, for receiving the light emitted from the emission surface and performing photoelectric conversion on the light; and a cylindrical imaging holder, protruding from at least part of an outer edge of one end in line with a side surface shape of the optical member, for defining the position of the incident surface and holding the optical member.

Abstract: An object is to provide an endoscope objective lens in which the aberrations are less susceptible to manufacturing errors and in which the variation in field curvature caused by focusing is small. There is provided an endoscope objective lens including: in sequence from an object side, a front group having negative refractive power, an aperture stop, and a rear group having positive refractive power; and a focusing lens that has a negative refractive power and that can be inserted into an optical path between the front group and the rear group. The focusing lens is inserted into the optical path in a normal observation state and is retracted from the optical path in a short-distance observation state, in which the working distance is smaller than that in the normal observation state.

Abstract: An endoscope apparatus includes an objective optical system mounted at a distal end portion of an endoscope, which is inserted into a tube cavity, and configured to form an image of an object in the tube cavity, the objective optical system including a focusing lens movable in an optical axis direction, a solid-state image pickup device for color image pickup configured to pick up the image formed by the objective optical system, a color separation filter being arranged for each pixel in the solid-state image pickup device, a focus adjusting mechanism configured to move the focusing lens and automatically adjust the objective optical system to a focus position in a focused state, a moving range switching section configured to perform switching of a moving range of the focusing lens, a moving range limiting section configured to limit the moving range in association with the switching by the moving range switching section, and the like.

Abstract: The depth of field is extended by using a simple structure. Provided is an imaging device comprising: an objective optical system that comprises an aperture stop that is disposed at an intermediate position on an optical axis and that has an opening that allows incident light from an object to pass therethrough; and an imaging element that acquires an optical image of the object, which is formed by the objective optical system, wherein pixels of the imaging element are arranged in a square along two mutually orthogonal axial directions, and the aperture stop includes a light-blocking portion at a portion aligned with the optical axis, the light-blocking portion having a square shape with sides inclined at 45° relative to the directions in which the pixels are arranged.

Abstract: An endoscope system has a light source apparatus and an endoscope including an illumination optical system and an objective optical system. At least the objective optical system of the endoscope is provided with an adjustable diaphragm, and in a light path in one of the light source apparatus, the illumination optical system, and the objective optical system, an insertable/retractable filter for observation for special light is provided. The adjustable diaphragm performs a closing operation or an opening operation only when the filter for observation for special light is inserted into the light path.

Abstract: An objective lens for an endoscope includes, in order from an object side, a front lens group having negative refractive power as a whole, a brightness aperture stop, and a rear lens group having positive refractive power as a whole. The front lens group includes, in order from the object side, a first lens group having negative refractive power and that may include only a single lens; and a second lens group that may include only a single lens, with the second lens group having a lens surface closest to the image side that is of a concave form directed toward the image side, the second lens group having positive refractive power as a whole; and the following condition (1) is satisfied: |f0/f1|?1.1??(1) where f0 is the composite focal length of the front lens group, and f1 is the focal length of the first lens group.

Abstract: An endoscope objective lens unit includes a front lens group and a rear lens group with a diaphragm interposed therebetween. The front lens group includes a first lens and a second lens, and the rear lens group includes a third lens, a fourth lens and a fifth lens. The endoscope objective lens unit satisfies following expressions (1A) to (4): (1A) ?3 <SF ?1; (2) ?3 <Fr/Ff <?1.1; (3) ?1.6 <Ff/f <?0.6; and (4) Ff/f1 <1.6, where SF is a shape factor, Ff is a focal length of the front lens group, Fr is a focal length of the rear lens group, f is a focal length of the entire unit, and f1 is a focal length of the first lens.

Abstract: An illumination optical system includes a prism disposed on an incident optical axis and a lens that is disposed between the light source and an incident surface of the prism or between an emitting surface of the prism and an illuminated object, at least one of the reflection surfaces being a transmission/reflection surface. Additionally, an illumination optical system includes a prism having a surface that is disposed so as to obliquely intersect with an incident optical system, that transmits a part of the entering light to be emitted therefrom, and that deflects at least part of the rest of the light in a direction that intersects with the incident optical axis to be emitted therefrom. Furthermore, an illumination optical system has a rod lens that is disposed so that a longitudinal direction thereof is inclined with respect to an incident optical axis is provided.

Abstract: An endoscope objective lens unit includes a front lens group and a rear lens group with a diaphragm interposed therebetween. The front lens group includes a first lens and a second lens, and the rear lens group includes a third lens, a fourth lens and a fifth lens. The endoscope objective lens unit satisfies following expressions (1A) to (4): (1A) ?3<SF??1; (2) ?3<Fr/Ff<?1.1; (3) ?1.6<Ff/f<?0.6; and (4) Ff/f1<1.6, where SF is a shape factor, Ff is a focal length of the front lens group, Fr is a focal length of the rear lens group, f is a focal length of the entire unit, and f1 is a focal length of the first lens.