Abstract: A wide-angle optical system includes a pair of front side lens units, an optical member, and a pair of rear side lens units. Each of the pair of front side lens units has a negative refractive power. The optical member has a pair of inclined surfaces and a bottom surface, and the pair of inclined surfaces is disposed such that a line of intersection is formed on an object side. Each of the pair of rear side lens units includes a positive lens, and in the pair of rear side lens units, two axes of rotational symmetry are parallel. With respect to two light rays, intersection and reflection occur at the optical member, and the intersection and the reflection occur after the two light rays are transmitted through the pair of inclined surfaces and before two light rays are transmitted through the bottom surface.

Abstract: A wide-angle optical system includes a pair of front side lens units, an optical member, and a pair of rear side lens units. Each of the pair of front side lens units has a negative refractive power. The optical member has a pair of inclined surfaces and a bottom surface, and the pair of inclined surfaces is disposed such that a line of intersection is formed on an object side. Each of the pair of rear side lens units includes a positive lens, and in the pair of rear side lens units, two axes of rotational symmetry are parallel. With respect to two light rays, intersection and reflection occur at the optical member, and the intersection and the reflection occur after the two light rays are transmitted through the pair of inclined surfaces and before two light rays are transmitted through the bottom surface.

Abstract: A set of negative meniscus lenses is a set which is to be used for an optical system having an angle of view not smaller than 240°. One negative meniscus lens in the set of negative meniscus lenses is located nearest to an object. The set of negative meniscus lenses has a predetermined lens surface, and the predetermined lens surface is a hemispherical surface or a surface extending beyond hemisphere.

Abstract: An optical system is an optical system in which an enlargement-side conjugate point positioned on an enlargement side and a reduction-side conjugate point positioned on a reduction side are conjugate. The optical system includes a super-hemispherical meniscus lens. The super-hemispherical meniscus lens has a reduction-side surface positioned on the reduction side and an enlargement-side surface positioned on the enlargement side. The reduction-side surface is a concave curved surface on the reduction side, and the enlargement-side surface is a convex curved surface on the enlargement side, having a positive refractive power. The curved surface of the enlargement-side surface is a curved surface extending beyond a hemisphere. An intersection of the reduction-side surface and an optical axis of the optical system is positioned closer to the enlargement side than the reduction-side conjugate point is.

Abstract: An endoscope includes a circular cylindrical member, a distal end member, and an image forming optical system. The circular cylindrical member has an inner peripheral surface and an outer peripheral surface. A space between the inner peripheral surface and the outer peripheral surface is filled with a transparent material. The distal end member is positioned at one end of the circular cylindrical member. The image forming optical system is disposed at an interior of the circular cylindrical member. The image forming optical system includes only transmitting surfaces and all the transmitting surfaces are disposed such that a normal of a plane at a point intersecting with the optical axis is aligned with the optical axis. The image forming optical system has a curvature of field, and the following conditional expression (1) is satisfied: ?10<P?<?0.8??(1).

Abstract: The optical system is characterized by a rotationally symmetric front group that is located on a single axis of rotational symmetry passing through the center of an image plane, a rotationally symmetric back group, and an aperture, wherein the front group includes two internal reflecting surfaces and two transmitting surfaces, a light beam incident from at least one object plane on the front group forms an optical path along which the light beam enters a first transmitting surface, is reflected off a first reflecting surface and then off a second reflecting surface, and exits out of a second transmitting surface, and the light beam passes through the back group and aperture and is imaged in a position of the image plane away from the axis of rotational symmetry without being intermediately imaged within a section including the axis of rotational symmetry.

Abstract: The stereoscopic imaging optical system 1 includes, in order from an object side thereof to an image plane side thereof, a front group Gf including a first front group Gf1 with a center axis C1 thereof as center and a second front group Gf2 with a center axis C2 thereof arranged parallel with the center axis of the first front group as center, a front deflection group Gfd located on an image plane side of at least one of the first front group Gf1 and the second front group, and a rear group Gb that is located on the image plane side of the front group Gf and the front deflection group Gfd and has a single center axis.

Abstract: A stereoscopic imaging optical system assembly including a first optical system at least including, in order from an object side to an image plane side, a negative lens and an aperture, the first optical system being rotationally symmetric with respect to a first center axis, a second optical system that is rotationally symmetric with respect to a second center axis parallel with the first center axis, and that has the same construction as, and is located in parallel with, the first optical system, and a variable optical system located in such a way as to intersect the respective optical paths through the first optical system and the second optical system. The variable optical system effects a change of at least either one of focus and vergence.

Abstract: An optical system 1 includes, in order from an object side to an image plane side, a front group Gf including a first front group Gf1 arranged centering a first front central axis Cf1 and a second front group Gf2 arranged centering a second front group central axis Cf2 as a rotation symmetry axis extending parallel to the first front group central axis Cf1; and a back group Gb arranged centering a single back group central axis Cb. A central principal ray of a first light beam L1 that has passed through the first front group Gf1 and a central principal ray of a second light beam L2 that has passed through the second front group Gf2 do not cross each other from when they exit from the back group Gb to when they reach the image plane.

Abstract: The optical system is characterized by a rotationally symmetric front group that is located on a single axis of rotational symmetry passing through the center of an image plane, a rotationally symmetric back group, and an aperture, wherein the front group includes two internal reflecting surfaces and two transmitting surfaces, a light beam incident from at least one object plane on the front group forms an optical path along which the light beam enters a first transmitting surface, is reflected off a first reflecting surface and then off a second reflecting surface, and exits out of a second transmitting surface, and the light beam passes through the back group and aperture and is imaged in a position of the image plane away from the axis of rotational symmetry without being intermediately imaged within a section including the axis of rotational symmetry.

Abstract: Provided is a three-dimensional-endoscope optical system that is provided with two objective optical systems having optical axes, which are arranged with a spacing therebetween, and that satisfies the following conditions: 0.5 mm<OP<1.5 mm??(1); 3 mm<D<200 mm??(2); ?<10°??(3); and 110°<?<180°??(4), where OP is a spacing between the optical axes of optical members at the most distal ends of the objective optical systems, D is a depth of field, ? is an angle of convergence (inward angle) of the depth of field D when performing near-point observation, and ? is an angle of view of the objective optical systems.

Abstract: A first central principal ray Lc1 of a first light beam L1 that has passed through a first front group Gf1 passes through a back first group Gb1, a first aperture center CS1, a first deflection group Gv1, and a back second group Gb2 at a position separated from a back group central axis Cb and reaches a image plane I, and a second central principal ray Lc2 of a second light beam L2 that has passed through a second front group Gf2 passes through the back first group Gb1, a second aperture center CS2, a second deflection group Gv2, and the back second group Gb2 at a position separated from the back group central axis Cb and reaches the image plane I.

Abstract: An optical system 1 includes, in order from an object side to an image plane side, a front group Gf including a first front group Gf1 arranged centering a first front central axis Cf1 and a second front group Gf2 arranged centering a second front group central axis Cf2 as a rotation symmetry axis extending parallel to the first front group central axis Cf1; and a back group Gb arranged centering a single back group central axis Cb. A central principal ray of a first light beam L1 that has passed through the first front group Gf1 and a central principal ray of a second light beam L2 that has passed through the second front group Gf2 do not cross each other from when they exit from the back group Gb to when they reach the image plane.

Abstract: The stereoscopic imaging optical system 1 includes, in order from an object side thereof to an image plane side thereof, a front group Gf including a first front group Gf1 with a center axis C1 thereof as center and a second front group Gf2 with a center axis C2 thereof arranged parallel with the center axis of the first front group as center, a front deflection group Gfd located on an image plane side of at least one of the first front group Gf1 and the second front group, and a rear group Gb that is located on the image plane side of the front group Gf and the front deflection group Gfd and has a single center axis.

Abstract: A stereoscopic imaging optical system assembly including a first optical system at least including, in order from an object side to an image plane side, a negative lens and an aperture, the first optical system being rotationally symmetric with respect to a first center axis, a second optical system that is rotationally symmetric with respect to a second center axis parallel with the first center axis, and that has the same construction as, and is located in parallel with, the first optical system, and a variable optical system located in such a way as to intersect the respective optical paths through the first optical system and the second optical system. The variable optical system effects a change of at least either one of focus and vergence.

Abstract: Provided is a three-dimensional-endoscope optical system that is provided with two objective optical systems having optical axes, which are arranged with a spacing therebetween, and that satisfies the following conditions: 0.5 mm<OP<1.5 mm??(1); 3 mm<D<200 mm??(2); ?<10°??(3); and 110°<?<180°??(4), where OP is a spacing between the optical axes of optical members at the most distal ends of the objective optical systems, D is a depth of field, ? is an angle of convergence (inward angle) of the depth of field D when performing near-point observation, and ? is an angle of view of the objective optical systems.

Abstract: In the visual display device of the present invention, the first reflection plane 11 is so disposed as to face the eye point 4 in order of an optical path of reverse tracing that extends from the eye point 4 to the two-dimensional image displaying plane 3; the second reflection plane 21 is so disposed as to face the two-dimensional image displaying plane 3, and an optical axis connecting the first reflection plane 11 to the eye point 4 is so disposed as to cross an optical axis connecting the second reflection plane 21 to the two-dimensional image displaying plane 3; both the first and second reflection planes 11 and 21 have positive power; and diopter difference S of the position of a virtual image associated with diopter is substantially equal to that of the position of a virtual image associated with convergence.

Abstract: The invention relates to an optical apparatus allowing images in multiple directions to be simultaneously taken with simple construction using a prism optical system yet with high definitions even at wide angles of view. Specifically, the invention provides an optical apparatus using a prism optical system which has three optical surfaces: a first surface having transmission, a second surface having internal reflection plus transmission and a third surface having reflection and is formed of a medium having a refractive index of 1.3 or greater and in which light enters the medium through the first surface, is totally reflected at the second surface, and then reflected at the third surface 13, and finally leaves the medium this time through the second surface.

Abstract: An image pickup apparatus is provided with an imaging optical system (imaging lens), an image sensor for picking up a subject image formed by the imaging optical system, and a view division optical system (first mirror) which divides a view picked up by the image sensor into an environment imaging side view and an eyeball imaging side view.

Abstract: The invention provides a superwide-angle imaging or projecting optical system provided that, albeit being a wide-angle optical system having an angle of view exceeding 180°, is of small size and reduced F-number and fast, and has improved f-? performance. The optical system consists only of transmitting surfaces, and has an angle of view of 180° or more. The optical system comprises a front group (Gf) comprising at least one meniscus lens (L1) having a negative focal length, an aperture (S), and a rear group (Gb) comprising at least two lenses having a positive focal length. At least one transmitting surface in the front group is made up of an extended rotation free-form surface.