Abstract: To allow placement of optical members by providing a long back focus, make aberrations less subject to manufacturing errors, and reduce variations in aberrations during focusing. An endoscopic objective optical system includes, in order from an object side, a front group with negative refractive power, a focusing lens, and a rear group with positive refractive power, wherein: the endoscopic objective optical system satisfies conditional expressions (1) to (4) below: 4<FB/FL??(1) FL/|fc|<0.1??(2) ?3<F_F/FL<?0.9??(3) 2.5<F_R/FL<5??(4) where FB is back focus of the entire system, FL is a focal length of the entire system, fc is a focal length of the focusing lens, |fc| is an absolute value of fc, F_F is a focal length of the front group, and F_R is a focal length of the rear group.

Abstract: This endoscope objective optical system is capable of acquiring images of high resolution and wide angle of observation field, maintaining low invasiveness and appropriately correcting various aberrations. This optical system has at least a first cemented lens which has a positive lens and a negative lens, in which the cemented lens satisfies the following conditional expressions. 15.0<?A?ndA<15.75??(1) ?0.2>rdyA1/ih>?20??(2) ?A is an Abbe number of the negative lens, ndA is a refractive index of the negative lens at the d-line, rdyA1 is a curvature radius of a joining surface of the negative lens, and ih is an image height.

Abstract: An endoscope optical system has a first lens group having positive refractive power, an aperture diaphragm, a second lens group having negative refractive power and a third lens group having positive refractive group, the second lens group moving along an optical axis to perform focusing, the first lens group having a first lens having negative refractive power and a second lens having positive refractive power, and the optical system satisfying the following conditional equation: ?5.0<H(76)*(1?nd01)/r2<?0.2??(1) 0.5<(r1+r2)/(r1?r2)<1.2??(2) where H(76) is a height at which a principal ray having an incidence angle of view of 76 degrees during normal observation passes through a surface on an image side of the first lens, nd01 is a refractive index of the first lens with respect to a line d, and r1 and r2 are respectively curvature radii of surfaces on the object side and the image side of the first lens.

Abstract: A fiber unit has an illumination fiber and detection fibers. The illumination fiber and the detection fiber comprise a soft portion that is bendable, a distal end hard portion provided at an end thereof and having a greater hardness than the soft portion, and a pitch conversion portion that connects the soft portion and the distal end hard portion and changes a distance between adjacent fibers at the distal end hard portion with respect to a distance between the adjacent fibers at the soft portion, by bending and extending. 1.0 degree<Deg_max<6.0 degrees, where Deg_max is a most inclined angle of angles each formed by a central axis of the distal end hard portion and a line segment connecting an end portion of the pitch conversion portion closer to the soft portion and an end portion of the pitch conversion portion closer the distal end hard portion.

Abstract: An endoscope optical system has a first lens group having positive refractive power, an aperture diaphragm, a second lens group having negative refractive power and a third lens group having positive refractive group, the second lens group moving along an optical axis to perform focusing, the first lens group having a first lens having negative refractive power and a second lens having positive refractive power, and the optical system satisfying the following conditional equation: ?5.0<H(76)*(1?nd01)/r2<?0.2??(1) 0.5<(r1+r2)/(r1?r2)<1.2??(2) where H(76) is a height at which a principal ray having an incidence angle of view of 76 degrees during normal observation passes through a surface on an image side of the first lens, nd01 is a refractive index of the first lens with respect to a line d, and r1 and r2 are respectively curvature radii of surfaces on the object side and the image side of the first lens.

Abstract: To allow placement of optical members by providing a long back focus, make aberrations less subject to manufacturing errors, and reduce variations in aberrations during focusing. An endoscopic objective optical system includes, in order from an object side, a front group with negative refractive power, a focusing lens, and a rear group with positive refractive power, wherein: the endoscopic objective optical system satisfies conditional expressions (1) to (4) below: 4<FB/FL??(1) FL/|Fc|<0.1??(2) ?3<F—F/FL<?0.9??(3) 2.5<F—R/FL<5??(4) where FB is back focus of the entire system, FL is a focal length of the entire system, fc is a focal length of the focusing lens, |fc| is an absolute value of fc, F_F is a focal length of the front group, and F_R is a focal length of the rear group.

Abstract: An optical measuring device includes: a light source unit; a measurement probe including a fiber bundle, an illumination fiber that illuminates a living tissue with a illumination light, and a plurality of light-receiving fibers that receives return light of the illumination light reflected and/or scattered at the living tissue; a detection unit that receives the return light of the illumination light detected by the plurality of respective light-receiving fibers, and performs photoelectric conversion to detect respective signal intensities; and an association unit that associates the respective signal intensities detected by the detection unit with distances from the illumination fiber to the respective light-receiving fibers on an end face of a distal end portion of the measurement probe, when light having an intensity gradient around the illumination fiber is projected to the end face of the distal end portion of the measurement probe.

Abstract: To off-axis and on-axis aberrations at low cost while having a wide angle of view, an endoscope objective optical system (1) has in order: a negative first lens (L1); a negative second lens (L2) and a third lens (L3) joined to each other; a brightness diaphragm (S); and a positive lens group (G2) having a cemented lens (CL2) including one positive lens and one negative lens joined to each other, and satisfies expressions (1) and (2): 1.0<D3(96 deg)/f_all<10 ??(1) 1.1<(r1+r2)/(r1?r2)<5.0 ??(2) where, D3(96 deg) is a distance in which a chief ray of a d-line having an incident angle of 96 degrees that enters the first lens transmits the third lens, f_all is a focal distance of the whole system, r1 and r2 are radii of curvature of an object side surface of the first lens and an image side surface of the second lens, respectively.

Abstract: A fiber unit has an illumination fiber and detection fibers. The illumination fiber and the detection fiber comprise a soft portion that is bendable, a distal end hard portion provided at an end thereof and having a greater hardness than the soft portion, and a pitch conversion portion that connects the soft portion and the distal end hard portion and changes a distance between adjacent fibers at the distal end hard portion with respect to a distance between the adjacent fibers at the soft portion, by bending and extending. 1.0 degree<Deg_max<6.0 degrees, where Deg_max is a most inclined angle of angles each formed by a central axis of the distal end hard portion and a line segment connecting an end portion of the pitch conversion portion closer to the soft portion and an end portion of the pitch conversion portion closer the distal end hard portion.

Abstract: A measurement probe includes an illumination fiber configured to irradiate a body tissue with illumination light, and a plurality of light receiving fibers configured to receive return light of the illumination light that is reflected and/or scattered from the body tissue. The illumination fiber and the light receiving fibers satisfy the following condition expressions: 0.21<NA<0.30 ??(1) 15 ?m<Dcore<45 ?m ??(2) 0.40<Dcore/Dclad<0.80 ??(3), where NA indicates a numerical aperture of each of the illumination fiber and the receiving fibers, Dcore indicates a core diameter of each of the illumination fiber and the light receiving fibers, and Dclad indicates a cladding diameter of each of the illumination fiber and the light receiving fibers.

Abstract: A measurement probe has a fiber bundle formed by irregularly bundling a plurality of optical fibers, is detachably connected to a bio-optical measurement apparatus performing optical measurement to a biological tissue that is an object to be measured, and includes a recording unit 35 that records positional information related to positions of an illumination fiber that emits light from a light source of the bio-optical measurement apparatus as illumination light and of a light-receiving fiber that receives returned light of the illumination light reflected and/or scattered at the biological tissue, the positions being at an end face of the fiber bundle, the end face being at an end that is attached to the bio-optical measurement apparatus.

Abstract: An endoscope optical system includes a negative lens that focuses light entering along an incident optical axis, a first prism that deflects and emits the light from the negative lens along a first axis substantially orthogonal to the incident optical axis, a second prism having a first reflecting surface, which deflects the light from the first prism along a second axis substantially orthogonal to the first axis, and a second reflecting surface that deflects and emits the light substantially parallel to the first axis and that faces the first prism, a third prism that deflects the light from the second prism substantially parallel to the incident optical axis, and a positive lens that focuses the light from the second prism, in this order from an object side, the negative lens and the first prism being rotatable about the first axis relative to the second prism.

Abstract: An optical system for an endoscope includes a negative lens-group, an aperture diaphragm and a positive lens-group in this order from an object side, wherein the negative lens-group includes a negative first-lens and a negative second-lens in this order from the object side; and wherein the optical system meets conditional expressions (1) and (2): 0.05<H(100)×(nd01?1)/Rf01<0.38??(1) and 0.5<enp/FL<2.5??(2), where: H(100) is a height at which a principal ray with a field angle of incidence of 100 degrees falls on a surface on the object side of the first lens; Rf01 is a curvature radius of the surface on the object side of the first-lens; nd01 is a refractive index of the first-lens; FL is a focal length of an entire system; and enp is a distance between an entrance pupil and the surface on the object side of the first lens.

Abstract: A zoom lens has a plurality of lens units including, in order from its object side to image side, a first lens unit having a negative refracting power composed of two lens elements including a biconcave negative lens and a positive lens, and a second lens unit having a positive refracting power composed of four lens elements including a positive lens and a negative lens. During zooming from the wide angle end to the telephoto end, a distance between the lens units changes, and the second lens unit moves toward the object side. The zoom lens has an aperture stop that moves integrally with the second lens during the zooming and satisfies a specific condition.

Abstract: A zoom lens has a plurality of lens units including, in order from its object side to image side, a first lens unit having a negative refracting power composed of two lens elements including a biconcave negative lens and a positive lens, and a second lens unit having a positive refracting power composed of four lens elements including a positive lens and a negative lens. During zooming from the wide angle end to the telephoto end, a distance between the lens units changes, and the second lens unit moves toward the object side. The zoom lens has an aperture stop that moves integrally with the second lens during the zooming and satisfies a specific condition.

Abstract: Provided is a diffractive optical element that is formed by laminating two optical material layers formed of different energy-cured resins; in which a relief pattern is formed at the interface between the two optical material layers; and that satisfies the following conditional expressions: 0.01<d2/d1<0.2??(1) 0.05<d1/?E<1.0??(2) 0.0005<d2/?E<0.1??(3) wherein d1 is the center plate thickness (mm) of one optical material layer 2 that is cured first, d2 is the center plate thickness (mm) of the other optical material layer 3 that is cured later, and ?E is the effective diameter (mm) of the relief pattern 4.

Abstract: A zoom lens comprises, in order from an object side, a first lens group with a negative refracting power; a second lens group with a positive refracting power; a third lens group with a positive refracting power; and a fourth lens group with a refracting curved surface. Upon zooming from a wide-angle end to telephoto end, at least the first lens group, second lens group, and third lens group move, and a spacing between the respective lens groups are changed. The first lens group comprises; in order from the object side to an image side, a negative lens component with a negative refracting power and a positive lens component with a positive refracting power which are arranged on an optical axis with a predetermined spacing therebetween. The total number of the lens components in the first lens group is two.

Abstract: A zoom lens has a plurality of lens units including, in order from its object side to image side, a first lens unit having a negative refracting power composed of two lens elements including a biconcave negative lens and a positive lens, and a second lens unit having a positive refracting power composed of four lens elements including a positive lens and a negative lens. During zooming from the wide angle end to the telephoto end, a distance between the lens units changes, and the second lens unit moves toward the object side. The zoom lens has an aperture stop that moves integrally with the second lens during the zooming and satisfies a specific condition.

Abstract: An endoscope optical system includes a negative lens that focuses light entering along an incident optical axis, a first prism that deflects and emits the light from the negative lens along a first axis substantially orthogonal to the incident optical axis, a second prism having a first reflecting surface, which deflects the light from the first prism along a second axis substantially orthogonal to the first axis and a second reflecting surface that deflects and emits the light, substantially parallel to the first axis and that faces the first prism, a third prism that deflects the light from the second prism substantially parallel to the incident optical axis, and a positive lens that focuses the light from the second prism, in this order from an object side, the negative lens and the first prism being rotatable about the first axis relative to the second prism.

Abstract: Provided is an imaging optical system and an image acquisition apparatus that can be suitably used in a small-diameter endoscope while having an ultra-wide angle of view. Provided is an image optical system (1) containing, in order from the object side, a negative front group (FG), an aperture stop (S), and a positive back group (BG), wherein the front group (FG) contains, in order from the object side, a negative first lens (L1) and a negative second lens (L2), and the back group (BG) contains a cemented lens (CL) constituted of at least three lenses (L5, L6, L7) joined together.