Abstract: An endoscope includes an insert part. The endoscope has an imaging unit provided in the insert part, a light guide having a light guide exit surface from which illumination light is emitted provided in the insert part and an end cover provided at the distal end of the insert part. The end cover has a cut-through portion in which the imaging unit is inserted and fixed. The end cover has a first surface on its object side, a second surface on its operator side, and a side surface on its outer circumference. The first surface includes a first flat surface and a curved surface. The curved surface is located between the first flat surface and the side surface. The second surface has an illumination area on which the illumination light is incident. At least a portion of the illumination area is formed as a partial torus surface. First specific cross sections are defined as cross sections containing the center axis of the end cover and intersecting the light guide exit surface.

Abstract: An endoscope includes an imaging system and an illumination system. The illumination system includes a light guide and at least one illumination lens, and the imaging system includes an objective lens unit and an image pickup element. When a direction along a long side of the image pickup element is set to be a first direction, and a direction along a short side of the image pickup element is set to be a second direction, the illumination system is disposed at a position shifted in the second direction with respect to the imaging system.

Abstract: There is provided an endoscope in which the generation of heat at a front-end portion is reduced. An endoscope includes an imaging system; and, an illumination system, wherein the illumination system includes a light guide and at least one illumination lens, and the imaging system includes an objective lens unit and an image pickup element, and when a direction along a long side of the image pickup element is let to be a first direction, and a direction along a short side of the image pickup element is let to be a second direction, the illumination system is disposed at a position shifted in the second direction with respect to the imaging system, and the endoscope satisfies the following conditional expressions (1), (2) and (3) 1.35<A ??(1) 1<LH/LV ??(2) 1.5<(rV?LV)/(rH?LH)?3.

Abstract: Provided is an endoscope objective optical system including, in order from an object side, a first group having negative refractive power, a second group having positive refractive power, and a third group having positive refractive power. The second group is provided so as to be movable in an optical-axis direction. The following conditional expression is satisfied, 9<f2/fa<16??(1) where f2 is a focal length of the second group, and fa is a focal length of the entire system in the normal observation state.

Abstract: Provided is an endoscope objective optical system including, in order from an object side, a first group having negative refractive power, a second group having positive refractive power, and a third group having positive refractive power. The second group is provided so as to be movable in an optical-axis direction. The following conditional expression is satisfied, 9<f2/fa<16??(1) where f2 is a focal length of the second group, and fa is a focal length of the entire system in the normal observation state.

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 endoscope objective optical system used in an endoscope has an objective optical system including a first lens group having a positive refractive power, an aperture stop, a second lens group having a negative refractive power and a third lens group having a positive refractive power, the first lens group, the aperture stop and the second and third lens group being successively disposed from the object side. The second lens group is made movable along an optical axis to change the focal length of the objective optical system. The lens surface at the object-side outermost position in the first lens group is formed so as to be convex on the object side.

Abstract: An endoscope objective optical system used in an endoscope has an objective optical system including a first lens group having a positive refractive power, an aperture stop, a second lens group having a negative refractive power and a third lens group having a positive refractive power, the first lens group, the aperture stop and the second and third lens group being successively disposed from the object side. The second lens group is made movable along an optical axis to change the focal length of the objective optical system. The lens surface at the object-side outermost position in the first lens group is formed so as to be convex on the object side.

Abstract: An endoscope has an insertion portion, a contact portion, an observation portion and a marking portion. The insertion portion can be inserted into a body cavity. The contact portion is provided at a distal end portion of the insertion portion. The contact portion provided at the distal end portion can be in contact with a subject. The observation portion is provided at the contact portion. The marking portion is provided at the contact portion. The marking portion applies a marker to the subject with which the contact portion is in contact.

Abstract: An endoscope has an insertion portion, an abutment portion, an increasing device and an observation portion. The insertion portion is an insertion portion which can be inserted into a subject. The abutment portion is provided at a distal end portion of the insertion portion. The abutment portion provided at the distal end portion can contact with the subject. The increasing device increases the abutment area of the abutment portion. The observation portion performs observation of the subject on the abutment portion provided at the distal end portion and having been increased by the increasing device, or performs observation of the subject spaced by a predetermined distance by the increased abutment portion.

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: The invention relates to an imaging system in which, while high image quality is maintained with the influence of diffraction minimized, the quantity of light is controlled, and which enables the length of the zoom lens to be cut down. The imaging system comprises a zoom lens comprising a plurality of lens groups G1 and G2 wherein the spacing between individual lens groups is varied to vary a focal length and an aperture stop located in an optical path for limiting at least an axial light beam diameter, and an electronic image pickup device I located on the image side of the zoom lens. The aperture stop has a fixed shape, and a filter S2 for performing light quantity control by varying transmittance is located on an optical axis of a space located at a position different from that of a space in which the aperture stop is located.

Abstract: A zoom optical system includes, in order from the object side, a first lens unit with positive refracting power, a second lens unit with negative refracting power, a third lens unit with positive refracting power, and a fourth lens unit with positive refracting power. An aperture stop is interposed between the second lens unit and the fourth lens unit. Upon zooming, at least, the first lens unit, the second lens unit, and the third lens unit are moved so that spacings between these lens units are varied. The first lens unit is constructed with at most two lens elements. The second lens unit includes, in order from the object side, a first negative lens in which the image-side surface is greater in curvature than the object-side surface, an air spacing, a second negative lens in which the image-side surface is greater in curvature than the object-side surface, an air spacing, and a positive lens in which the object-side surface is greater in curvature than the image-side surface.

Abstract: The invention relates to an imaging system in which, while high image quality is maintained with the influence of diffraction minimized, the quantity of light is controlled, and which enables the length of the zoom lens to be cut down. The imaging system comprises a zoom lens comprising a plurality of lens groups G1 and G2 wherein the spacing between individual lens groups is varied to vary a focal length and an aperture stop located in an optical path for limiting at least an axial light beam diameter, and an electronic image pickup device I located on the image side of the zoom lens. The aperture stop has a fixed shape, and a filter S2 for performing light quantity control by varying transmittance is located on an optical axis of a space located at a position different from that of a space in which the aperture stop is located.

Abstract: A zoom optical system includes, in order from the object side, a first lens unit with positive refracting power, a second lens unit with negative refracting power, a third lens unit with positive refracting power, and a fourth lens unit with positive refracting power. An aperture stop is interposed between the second lens unit and the fourth lens unit. Upon zooming, at least, the first lens unit, the second lens unit, and the third lens unit are moved so that spacings between these lens units are varied. The first lens unit is constructed with at most two lens elements. The second lens unit includes, in order from the object side, a first negative lens in which the image-side surface is greater in curvature than the object-side surface, an air spacing, a second negative lens in which the image-side surface is greater in curvature than the object-side surface, an air spacing, and a positive lens in which the object-side surface is greater in curvature than the image-side surface.

Abstract: A zoom optical system includes, in order from the object side, a first lens unit with positive refracting power, a second lens unit with negative refracting power, a third lens unit with positive refracting power, and a fourth lens unit with positive refracting power. An aperture stop is interposed between the second lens unit and the fourth lens unit. Upon zooming, at least, the first lens unit, the second lens unit, and the third lens unit are moved so that spacings between these lens units are varied. The first lens unit is constructed with at most two lens elements. The second lens unit includes, in order from the object side, a first negative lens in which the image-side surface is greater in curvature than the object-side surface, an air spacing, a second negative lens in which the image-side surface is greater in curvature than the object-side surface, an air spacing, and a positive lens in which the object-side surface is greater in curvature than the image-side surface.

Abstract: The invention relates to a zoom optical system wherein various aberrations are corrected while the total thickness of a lens arrangement upon received at a collapsible lens mount is reduced thereby ensuring compactness, high image-formation capabilities, and high zoom ratios at the wide-angle end, and an imaging system that incorporates the same. The zoom optical system comprises a first lens group G1 of negative refracting power and a second lens group G2 of positive refracting power. The first lens group G1 comprises a negative single lens comprising at least one aspheric surface and a positive single lens with an air separation interposed between the negative single lens and the positive single lens. The second lens group G2 comprises a positive lens, a cemented lens consisting of a positive lens and a negative lens and a positive lens, and comprises at least one aspheric surface. Zooming is carried out by varying a spacing between the respective lens groups.

Abstract: A zoom optical system includes, in order from the object side, a first lens unit with positive refracting power, a second lens unit with negative refracting power, a third lens unit with positive refracting power, and a fourth lens unit with positive refracting power. An aperture stop is interposed between the second lens unit and the fourth lens unit. Upon zooming, at least, the first lens unit, the second lens unit, and the third lens unit are moved so that spacings between these lens units are varied. The first lens unit is constructed with at most two lens elements. The second lens unit includes, in order from the object side, a first negative lens in which the image-side surface is greater in curvature than the object-side surface, an air spacing, a second negative lens in which the image-side surface is greater in curvature than the object-side surface, an air spacing, and a positive lens in which the object-side surface is greater in curvature than the image-side surface.

Abstract: The invention relates to a zoom optical system wherein various aberrations are corrected while the total thickness of a lens arrangement upon received at a collapsible lens mount is reduced thereby ensuring compactness, high image-formation capabilities, and high zoom ratios at the wide-angle end, and an imaging system that incorporates the same. The zoom optical system comprises a first lens group G1 of negative refracting power and a second lens group G2 of positive refracting power. The first lens group G1 comprises a negative single lens comprising at least one aspheric surface and a positive single lens with an air separation interposed between the negative single lens and the positive single lens. The second lens group G2 comprises a positive lens, a cemented lens consisting of a positive lens and a negative lens and a positive lens, and comprises at least one aspheric surface. Zooming is carried out by varying a spacing between the respective lens groups.

Abstract: The invention provides a zoom lens that operates in such a zooming mode and zoom arrangement that the number of lens elements is reduced to make the total thickness of each lens group thin while stable yet high image-formation capability is maintained, thereby achieving thorough size reductions in video cameras or digital cameras, and an electronic imaging system using the same. The zoom lens comprises a first lens group G1 of negative refracting power, a second lens group G2 of positive refracting power and a third lens group G3 of positive refracting power. For zooming from the wide-angle end to the telephoto end of the zoom lens upon focused on an infinite object point, the second lens group G2 moves toward the object side alone of the zoom lens, and the third lens group G3 moves in a locus different from that of the second lens group while the spacing between adjacent lens groups varies. The second lens group G2 is composed of two lens components, i.e.