Abstract: An imaging optical system includes a positive or negative first lens group, a diaphragm and a positive second lens group. The first lens group includes a positive lens element, provided closest to the object side, that has an aspherical surface on the object side thereof, the aspherical surface including a paraxial convex surface convexing toward the object side. This aspherical surface has a curvature that is positive along a meridional cross-section at the paraxial portion thereof, and the curvature of the meridional cross-section changes from a positive value to a negative value in an area within 75% of an effective aperture from the paraxial portion toward the periphery of the aspherical surface.

Abstract: An imaging optical system includes a positive first lens group, a diaphragm and a positive second lens group. The first lens group includes a positive lens element, provided closest to the object side, that has an aspherical surface on the object side thereof, the aspherical surface including a paraxial convex surface convexing toward the object side. This aspherical surface has a curvature that is positive along a meridional cross-section at the paraxial portion thereof, and the curvature of the meridional cross-section changes from a positive value to a negative value in an area within 75% of an effective aperture from the paraxial portion toward the periphery of the aspherical surface.

Abstract: The object-side surface of a negative lens element closest to the object side within a first lens group includes a paraxial convex surface and a peripheral surface having a curvature less than that of the paraxial surface. The image-side surface of a last lens element of a second lens group includes a paraxial concave surface and a peripheral surface having an inflection point changing from positive to negative values. 0.10<La/TL<0.31, and 0.35<Bh<0.70 are satisfied; La: distance from the object-side surface of the negative lens element, closest to the object side, to an axial light-bundle restriction diaphragm closest to the object side; TL: distance from the object-side surface of this negative lens element to an imaging surface; Bh: height to an inflection point on the image side of the lens element closest to the image side divided by the effective radius thereof.

Abstract: The object-side surface of a negative lens element closest to the object side within a first lens group includes a paraxial convex surface and a peripheral surface having a curvature less than that of the paraxial surface. The image-side surface of a last lens element of a second lens group includes a paraxial concave surface and a peripheral surface having an inflection point changing from positive to negative values. 0.10<La/TL<0.31, and 0.35<Bh<0.70 are satisfied; La: distance from the object-side surface of the negative lens element, closest to the object side, to an axial light-bundle restriction diaphragm closest to the object side; TL: distance from the object-side surface of this negative lens element to an imaging surface; Bh: height to an inflection point on the image side of the lens element closest to the image side divided by the effective radius thereof.

Abstract: An imaging optical system includes a positive or negative first lens group, a diaphragm and a positive second lens group. The first lens group includes a positive lens element, provided closest to the object side, that has an aspherical surface on the object side thereof, the aspherical surface including a paraxial convex surface convexing toward the object side. This aspherical surface has a curvature that is positive along a meridional cross-section at the paraxial portion thereof, and the curvature of the meridional cross-section changes from a positive value to a negative value in an area within 75% of an effective aperture from the paraxial portion toward the periphery of the aspherical surface.

Abstract: A zoom optical system includes a negative first lens group having a first deflection optical element, a positive second lens group, a positive third lens group, a positive fourth lens group, and a second deflection optical element, in that order from the object side. The first lens group is provided at a fixed position relative to an imaging plane. Zooming is performed by moving at least the second and third lens groups so that distances between adjacent lens groups of the first through fourth lens groups change. The third lens group is a focusing lens group which moves along the optical axis during focusing. The following condition (1) is satisfied: 0.2<f3/f4<1.0??(1), wherein f3 designates the focal length of the third lens group, and f4 designates the focal length of the fourth lens group.

Abstract: An imaging apparatus includes a front lens group having a front lens element and a reflector, in that order from an object side. The reflector includes a reflection surface which reflects light rays, from the front lens element, toward a different direction; a rear lens group positioned closer to an image plane than the front lens group, the imaging apparatus performs an image-stabilizing operation by driving the front lens element, a movable frame holding the front lens element; a support member supporting the reflector and is immovable relative to an optical axis of the front lens element, in a reference state; and a support mechanism which supports the movable frame to spherically swing about a spherical-swinging center, positioned on an extension of the optical axis of the front lens element extending behind an underside of the reflection surface of the reflector.

Abstract: A zoom optical system includes a negative first lens group having a first deflection optical element, a positive second lens group, a positive third lens group, a positive fourth lens group, and a second deflection optical element, in that order from the object side. The first lens group is provided at a fixed position relative to an imaging plane. Zooming is performed by moving at least the second and third lens groups so that distances between adjacent lens groups of the first through fourth lens groups change. The third lens group is a focusing lens group which moves along the optical axis during focusing. The following condition (1) is satisfied: 0.2<f3/f4<1.0??(1), wherein f3 designates the focal length of the third lens group, and f4 designates the focal length of the fourth lens group.

Abstract: An imaging optical system includes a bending optical element which bends an object-emanating light bundle, a post-bending lens system on a post-bending optical axis defined by the bending optical element, and an image sensor. An effective optical surface of a large-diameter lens element, having a greatest axial light bundle effective radius, is formed into a non-circular shape by making a length of the effective optical surface from the post-bending optical axis toward a side opposite from the object side smaller than the axial light bundle effective radius, with reference to the axial light bundle effective radius lying on a plane which extends orthogonal to a plane including both the post-bending optical axis and a pre-bending optical axis of the imaging optical system and includes the post-bending optical axis.

Abstract: An imaging apparatus includes a front lens group having a front lens element and a reflector, in that order from an object side. The reflector includes a reflection surface which reflects light rays, from the front lens element, toward a different direction; a rear lens group positioned closer to an image plane than the front lens group, the imaging apparatus performs an image-stabilizing operation by driving the front lens element, a movable frame holding the front lens element; a support member supporting the reflector and is immovable relative to an optical axis of the front lens element, in a reference state; and a support mechanism which supports the movable frame to spherically swing about a spherical-swinging center, positioned on an extension of the optical axis of the front lens element extending behind an underside of the reflection surface of the reflector.

Abstract: An imaging optical system includes a bending optical element which bends an object-emanating light bundle, a post-bending lens system on a post-bending optical axis defined by the bending optical element, and an image sensor. An effective optical surface of a large-diameter lens element, having a greatest axial light bundle effective radius, is formed into a non-circular shape by making a length of the effective optical surface from the post-bending optical axis toward a side opposite from the object side smaller than the axial light bundle effective radius, with reference to the axial light bundle effective radius lying on a plane which extends orthogonal to a plane including both the post-bending optical axis and a pre-bending optical axis of the imaging optical system and includes the post-bending optical axis.

Abstract: An imaging optical system, which includes an imaging lens group having at least one lens, and an image side prism that bends light which has passed through the imaging lens group toward an image pickup device arranged at a predetermined position, and wherein the image side prism includes a reflection surface which reflects, toward the image pickup device, incident light proceeding from the imaging lens group and an exit surface from which light reflected from the reflection surface emerges, and wherein the image side prism has a cut surface formed by cutting off a vertex portion between the reflection surface and the exit surface such that a whole normal light incident area within which normal light is incident on the reflection surface remains, and the cut surface is a non-diffusing surface.

Abstract: A simulation is configured including: an image generation part configured to generate mutually different two images as an image which is viewed by right and left eyes respectively through a lens in a monovision prescription state, when a relation between a point spread function and a distance is set in a different state by wearing the lens in the monovision prescription state; and an image displayer configured to display the two different images generated by the image generation part individually for each of the right and left eyes of an examinee.

Abstract: An imaging optical system, including an imaging lens group, an image side prism having an entrance surface a reflection surface and an exit surface from which light exits toward an image pickup device, and a first shielding member shielding at least a part of a region on the entrance surface, wherein the region on the entrance surface is located from an edge line of an apex between the entrance surface and the exit surface to a position corresponding to a height h from the edge line, and when L represents a length of the exit surface, ? represents an angle formed between the reflection surface and the exit surface, n represents a refractive index of a surrounding area of the image side prism, and n? represents a refractive index of the image side prism, the height h satisfies a following condition: h=L×cos {?+sin?1(n/n?)}.

Abstract: A variable power optical system, including a fixed negative first lens group, a second positive lens group and a third positive lens group, wherein the first lens group includes a deflecting element arranged to bend an optical path, and when d12w denotes a distance between an image side principal point of the first lens group and an object side principal point of the second lens group at a short focal length end, d12t denotes a distance between the image side principal point of the first lens group and the object side principal point of the second lens group at a long focal length end, fw denotes a focal length of the optical system at the short focal length end, ft denotes a focal length of the optical system at the long focal length end, and f1 denotes a focal length of the first lens group, the optical system satisfies: 2.5<(d12w/d12t)/|?{square root over (fw×ft)}/f1|<4.0.

Abstract: An imaging optical system, including an imaging lens group, an image side prism having an entrance surface a reflection surface and an exit surface from which light exits toward an image pickup device, and a first shielding member shielding at least a part of a region on the entrance surface, wherein the region on the entrance surface is located from an edge line of an apex between the entrance surface and the exit surface to a position corresponding to a height h from the edge line, and when L represents a length of the exit surface, ? represents an angle formed between the reflection surface and the exit surface, n represents a refractive index of a surrounding area of the image side prism, and n? represents a refractive index of the image side prism, the height h satisfies a following condition: h=L×cos {?+sin?1(n/n?)}.

Abstract: An imaging optical system, which includes an imaging lens group having at least one lens, and an image side prism that bends light which has passed through the imaging lens group toward an image pickup device arranged at a predetermined position, and wherein the image side prism includes a reflection surface which reflects, toward the image pickup device, incident light proceeding from the imaging lens group and an exit surface from which light reflected from the reflection surface emerges, and wherein the image side prism has a cut surface formed by cutting off a vertex portion between the reflection surface and the exit surface such that a whole normal light incident area within which normal light is incident on the reflection surface remains, and the cut surface is a non-diffusing surface.

Abstract: A variable power optical system, including a fixed negative first lens group, a second positive lens group and a third positive lens group, wherein the first lens group includes a deflecting element arranged to bend an optical path, and when d12w denotes a distance between an image side principal point of the first lens group and an object side principal point of the second lens group at a short focal length end, d12t denotes a distance between the image side principal point of the first lens group and the object side principal point of the second lens group at a long focal length end, fw denotes a focal length of the optical system at the short focal length end, ft denotes a focal length of the optical system at the long focal length end, and f1 denotes a focal length of the first lens group, the optical system satisfies: 2.5<(d12w/d12t)/|?{square root over (fw×ft)}/f1|<4.

Abstract: An imaging optical system, which is provided with an imaging lens group having at least one lens, an image side prism that bends light which has passed through the imaging lens group toward an image pickup device arranged at a predetermined position, and a cover glass that is provided for the image pickup device and lets the light bent by the image side prism pass therethrough, and wherein an exist surface of the image side prism from which the light bent by the image side prism emerges and an entrance surface of the cover glass are adhered to each other with an adhesive which is optically transparent.

Abstract: An imaging unit including an image sensor, an incident-side prism, an exit-side prism, and an intermediate optical system positioned therebetween, wherein light incident on the incident-side prism passes through the incident-side prism, the intermediate optical system and the exit-side prism to be incident on the image sensor, the imaging unit includes a housing supporting the incident-side prism, the exit-side prism and the intermediate optical system such that incident and exit optical axes of the incident-side prism, an optical axis of the intermediate optical system, and incident and exit optical axes of the exit-side prism all lie on a common plane; and a cover board, on which the image sensor is mounted, fixed to the housing so that the image sensor faces an exit surface of the exit-side prism, the cover board closing an opening of the housing.