An endoscope or the like that prevents crosstalk between multiple light-emitting parts is provided. An endoscope includes: an observation window that is disposed at a distal end of an insertion part; a plurality of first light-emitting parts that are disposed around the observation window; a second light-emitting part that is disposed between the first light-emitting parts and emits light at a bandwidth different from a bandwidth of light emitted by the first light-emitting parts; and a light-shielding body that is disposed between one of the first light-emitting parts and the second light-emitting part.

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 −1.6<f.sub.F/f.sub.R<−1.2 and −1.0<SF.sub.5<−0.5. f.sub.F and f.sub.R are the focal lengths of the front lens group and the rear lens group, SF.sub.5 is (R.sub.51+R.sub.52)/(R.sub.51−R.sub.52), and R.sub.51 and R.sub.52 are respectively the curvature radiuses of surfaces.

There is provided an objective optical system that is easy to produce, capable of forming optical images that can be observed without difficulties while small in size. The objective optical system includes, in order from the object side, a flat plate OP1, an aperture stop S, and a substantially hemispherical planoconvex lens L1 having an outer diameter substantially equal to the outer diameter of the flat plate. The flat plate and the planoconvex lens L1 are cemented together with the aperture stop between. The objective optical system satisfies the following conditional expressions (1), (2), and (3): 0.3<IH/Dp<0.45 (1) 1.7<1+Dp×ωr/(2×IH)<2.1 (2) 0.9<NL/(1+Dp×ωr/(2×IH))<1.1 (3).

An objective optical system includes in order from an object side, a front unit having a positive refractive power and a rear unit. The front unit includes in order from the object side, a first lens having a negative refractive power, a second lens having a positive refractive power, and a third lens having a positive refractive power. The rear unit includes one lens or a plurality of lenses and the following conditional expression is satisfied:
|(FLag−FLaC)/FLad|<0.05  (1) where, FLad denotes a focal length for a d-line of the front unit, FLag denotes a focal length for a g-line of the front unit, and FLaC denotes a focal length for a C-line of the front unit.

An objective optical system for an endoscope consisting of, in order from an object side toward an image side: a front group; and a rear group, wherein: the front group consists of, in order from the object side toward the image side: one negative lens; an optical path deflecting prism; an aperture stop; and one positive lens. The objective optical system for an endoscope satisfies a predetermined conditional expression.

The present invention relates to an endoscope including an object, which is to be supplied with electric current, in an endoscope head of the endoscope, and a circuit board for the object to be supplied with electric current. The circuit board extends from the object, which is to be supplied with electric current, in the distal direction of the endoscope head.

An optical probe assembly as a confocal endomicroscope includes an optical focusing stage that focuses an output beam onto a sample and a mirror scanning stage that is movable for scanning the output beam in both a lateral two dimensional plane and an axial direction, using a side-view configuration. The side-view configuration allows for output beam illumination and fluorescent imaging of the sample with greater imaging resolution and improved access to hard to reach tissue within a subject.

Optical imaging systems configured to image object space in multiple fields-of-view (FOVs)—front and lateral FOVs—and form corresponding images that are co-oriented and co-directional regardless of mutual repositioning of the object and imaging systems. Images formed with such optical systems in which FFOV— and LFOV-image portions are co-directional. Co-directionality of formed images is achieved due to direct imaging with a system utilizing a specific involute reflective surface or as a result of radial spatial redistribution of irradiance of an initial image(s), formed with a system devoid of an involute reflective surface, while maintaining aspect ratios of dimensions of corresponding pixels of initial and transformed images. Methodology of transformation of images utilizing radial redistribution of image irradiance.

There is provided an objective optical system, an image pickup apparatus, and an endoscope that are short in overall length and simple in structure and have a focusing function. The objective optical system includes, in order from the object side to the image side, a positive front lens group and a positive rear lens group. Focusing is performed by moving the front lens group along the optical axis. The front lens group includes, in order from the object side, a negative first lens, a positive second lens, an aperture stop, and a positive third lens, as lenses having refractive power. The rear lens group includes, in order from the object side, a positive cemented fourth lens and a positive fifth lens having a convex surface facing toward the object. The objective optical system satisfies the following conditional expression (1):

0.35<FL/Ff<0.85  (1).

There is provided an objective optical system, an image pickup apparatus, and an endoscope that are small in size and easy to assemble. The objective optical system includes, in order from the object side to the image side, a negative front lens group, an aperture stop, and a positive rear lens group. The front lens group includes a negative first lens disposed closest to the object, a meniscus second lens having a convex surface facing toward the image side, and a view-direction changing element. The objective optical system satisfies the following conditional expressions (1) to (4):

9<FL2/FL<15 (1)

0.3<FL1/FLf <0.64 (2)

95<(r2f+r2r)/(r2f-r2r)<−18 (3)

2.8<FLr/FL<4 (4).