Abstract: A zoom lens includes a first optical system having a positive focal length, the first optical system, a second optical system having a negative focal length, a third optical system having a positive focal length, a fourth optical system having a negative focal length, and a fifth optical system having a positive focal length, which are arranged in order from an object side to an image side and an aperture stop provided at an object side of the third optical system. The following condition is satisfied: 0.5<(T23w/Y?)/(ft/fw)<1.0 where T23w is an interval between the second optical system and the third optical system at the short focus end, Y? is a maximum image height of the zoom lens, ft is a focal length of the zoom lens at the long focus end, and fw is a focal length of the zoom lens at the short focus end.

Abstract: A zoom lens includes a first lens group having a positive refracting power, a second lens group having a negative refracting power, a third lens group having a positive refracting power, and a fourth lens group having a positive refracting power, being disposed in order from an object side, and an aperture stop disposed at an object side of the third lens group. When changing the magnification from a wide angle end to a telephoto end, an interval between the first and second lens groups increases, an interval between the second and third lens groups decreases, and an interval between the third and fourth lens groups changes.

Abstract: A zoom lens unit includes, in order from an object side to an image side: a first lens group having a positive refracting power; a second lens group having a negative refracting power; a third lens group having a positive refracting power; a fourth lens group having a negative refracting power; a fifth lens group having a positive refracting power; and a sixth lens group having a negative refracting power, an aperture stop is disposed between the second lens group and the third lens group, and when changing magnification from a wide-angle end to a telephoto end, at least the second lens group, the third lens group and the fifth lens group are moved, and the first lens group includes a reflecting optical element which bends a light path in the first lens group to obtain a predetermined light path length.

Abstract: A zoom lens includes a first lens group having a positive focal length, a second lens group having a negative focal length, a third lens group having a positive focal length, a fourth lens group having a negative focal length which are arranged in order from an object side to an image side, and a diaphragm disposed between the second and third lens groups. During a change of zoom ratio from short to long focus end, the first to fourth lens groups move so that an interval between the first and second lens groups increases, an interval between the second and third lens groups decreases, and an interval between the third and fourth lens groups increases. The first lens group includes first and second negative lenses, a reflective optical element, and at least one positive lens arranged in order from the object side to the image side.

Abstract: A zoom lens includes, in order along an optical axis from a side nearest to a photographic subject to an imaging site, a first lens group I that comprises a positive refraction index and is anchored in place when performing a magnification of an image, a second lens group II that comprises a negative refraction index, a third lens group III that comprises a positive refraction index, a fourth lens group IV that comprises a positive refraction index, a fifth lens group V that comprises a negative refraction index, and a sixth lens group VI that comprises a positive refraction index, wherein, when magnifying from a wide angle end to a telephoto end, the magnification thereof is performed by moving the second lens group II, the fourth lens group IV, and the fifth lens group V, at a minimum, the first lens group I comprises a reflective optical element, which is for refracting a light path therein, an additional lens group VII, comprising a negative refraction index, is interposed between the lens groups of the z

Abstract: A zoom lens includes a first optical system having a positive focal length, the first optical system, a second optical system having a negative focal length, a third optical system having a positive focal length, a fourth optical system having a negative focal length, and a fifth optical system having a positive focal length, which are arranged in order from an object side to an image side and an aperture stop provided at an object side of the third optical system. The following condition is satisfied: 0.5<(T23w/Y?)/(ft/fw)<1.0 where T23w is an interval between the second optical system and the third optical system at the short focus end, Y? is a maximum image height of the zoom lens, ft is a focal length of the zoom lens at the long focus end, and fw is a focal length of the zoom lens at the short focus end.

Abstract: A zoom lens includes a first lens group having a positive focal length, a second lens group having a negative focal length, a third lens group having a positive focal length, a fourth lens group having a negative focal length which are arranged in order from an object side to an image side, and a diaphragm disposed between the second and third lens groups. During a change of zoom ratio from short to long focus end, the first to fourth lens groups move so that an interval between the first and second lens groups increases, an interval between the second and third lens groups decreases, and an interval between the third and fourth lens groups increases. The first lens group includes first and second negative lenses, a reflective optical element, and at least one positive lens arranged in order from the object side to the image side.

Abstract: A zoom lens unit includes, in order from an object side to an image side: a first lens group having a positive refracting power; a second lens group having a negative refracting power; a third lens group having a positive refracting power; a fourth lens group having a negative refracting power; a fifth lens group having a positive refracting power; and a sixth lens group having a negative refracting power, an aperture stop is disposed between the second lens group and the third lens group, and when changing magnification from a wide-angle end to a telephoto end, at least the second lens group, the third lens group and the fifth lens group are moved, and the first lens group includes a reflecting optical element which bends a light path in the first lens group to obtain a predetermined light path length.

Abstract: A scanning and imaging optical system that condenses beams of light deflected by an optical deflector toward a surface to be scanned to form a light spot for optical scanning on the surface includes plurality of scanning lenses. Among the scanning lenses, at least two of the scanning lenses are resin lenses that are formed by plastic molding, and where a position coordinate in a horizontal scanning direction or in a vertical scanning direction is X, refractive index distribution in a cross-section with respect to the position coordinate X is ?n(X), the refractive index distribution in a cross-section in the horizontal scanning direction that includes an optical axis or in the vertical scanning direction of the resin lenses, signs of the refractive index distribution ?n(X) at least in the vertical scanning direction are not identical for all of the resin lenses.

Abstract: A zoom lens includes, in order along an optical axis from a side nearest to a photographic subject to an imaging site, a first lens group I that comprises a positive refraction index and is anchored in place when performing a magnification of an image, a second lens group II that comprises a negative refraction index, a third lens group III that comprises a positive refraction index, a fourth lens group IV that comprises a positive refraction index, a fifth lens group V that comprises a negative refraction index, and a sixth lens group VI that comprises a positive refraction index, wherein, when magnifying from a wide angle end to a telephoto end, the magnification thereof is performed by moving the second lens group II, the fourth lens group IV, and the fifth lens group V, at a minimum, the first lens group I comprises a reflective optical element, which is for refracting a light path therein, an additional lens group VII, comprising a negative refraction index, is interposed between the lens groups of the z

Abstract: A holding mechanism for a long length optical element, which extends in a main scanning direction that is a movement direction of a deflected luminous flux by an optical deflector, and leads the deflected luminous flux to a scanned surface, includes; a holding member which is placed in a sub-scanning direction orthogonal to the main scanning direction and holds the long length optical element in at least two places. The holding member has, an adjusting section which deflects the long length optical element in the sub-scanning direction and controls a tilt of the long length optical element in a sub-scanning cross-section and/or occurrences of a tilt distribution in a longitudinal direction in the sub-scanning cross-section.

Abstract: An optical scanner includes a light source, an optical coupler, an optical line image unit, a deflector, and an optical scanning unit. The optical scanning unit includes scanning lenses that guide the beams to a surface to be scanned. A surface on the deflector side of the scanning lens closest to a deflection reflecting surface has a negative power in a vertical scanning direction, and is a special toric surface in which a radius of curvature in a vertical scanning changes from an optical axis of the lens surface toward a periphery of the horizontal scanning direction. An F number of the beams toward the surface to be scanned of the scanning lens in the vertical scanning direction is larger in a peripheral part than in a central part in an effective scanning width.

Abstract: An optical scanner includes a light source, an optical coupler, an optical line image unit, a deflector, and an optical scanning unit. The optical scanning unit includes scanning lenses that guide the beams to a surface to be scanned. A surface on the deflector side of the scanning lens closest to a deflection reflecting surface has a negative power in a vertical scanning direction, and is a special toric surface in which a radius of curvature in a vertical scanning changes from an optical axis of the lens surface toward a periphery of the horizontal scanning direction. An F number of the beams toward the surface to be scanned of the scanning lens in the vertical scanning direction is larger in a peripheral part than in a central part in an effective scanning width.

Abstract: An optical scanner includes a light source, an optical coupler, an optical line image unit, a deflector, and an optical scanning unit. The optical scanning unit includes scanning lenses that guide the beams to a surface to be scanned. A surface on the deflector side of the scanning lens closest to a deflection reflecting surface has a negative power in a vertical scanning direction, and is a special toric surface in which a radius of curvature in a vertical scanning changes from an optical axis of the lens surface toward a periphery of the horizontal scanning direction. An F number of the beams toward the surface to be scanned of the scanning lens in the vertical scanning direction is larger in a peripheral part than in a central part in an effective scanning width.

Abstract: An optical scanner has a deflector, a coupling lens, a cylindrical lens, a plate through which light to and from the deflector pass, and an optical system which condenses the light deflected on a surface to be scanned. Bundles of light beams incident on the deflector have an angle between the bundles in a rotating plane of the deflector, and expressions 0.6<(?1max??)/(?2+?)<1.4, and 0.6<(?1min??)/(?2+?)<1.4, are satisfied, where ?1max and ?1min are maximum and minimum average angles of incidence on the deflecting surface, ?2 is a half-view angle, and ? is an angle of inclination of the plate in the rotating plane with respect to a main scanning direction.

Abstract: An optical scanner includes a single deflector to optically scan a plurality of target surfaces. The deflector is shared by all the beams from a plurality of light sources. The optical scanner includes photodetectors arranged to receive the deflected beams deflected. The beams traveling toward the deflector have an open angle in a deflecting rotation plane. A plurality of scanning optical systems are arranged to guide the deflected beams to different target surfaces. Each of the scanning optical systems includes at least two identical scanning lenses. At least one specific scanning lens in the scanning optical system is at a position rotated 180 degrees from a corresponding specific scanning lens in another scanning optical system. The specific scanning lens has a sub scan curvature on at least one surface with a shape asymmetrically varying from an optical axis toward both peripheries in the main scan direction.

Abstract: An optical scanner includes a single deflector to optically scan a plurality of target surfaces to be scanned. The deflector has a common rotary axis for deflecting reflective surfaces and is shared by all the beams from a plurality of light sources. The optical scanner includes photodetectors arranged to receive the beams deflected at the deflector. The beams traveling toward the deflector have an open angle in a deflecting rotation plane. A scanning optical system for guiding the deflected beam to the corresponding target surface includes two or more scanning lenses. A scanning lens proximate to the target surface passes only the beams traveling toward the same target surface. Scanning lenses proximate to the target surfaces for guiding the beams to different target surfaces have optical actions different from each other.

Abstract: A scanning optical system condensing a beam deflected by an optical deflector so as to form a beam spot on a surface to be scanned, comprises two lenses. A lens on the side of optical deflector has a negative refracting power in sub-scanning direction. A lens on the side of surface to be scanned has a positive refracting power in the sub-scanning direction. At least one lens surface of the lens surfaces of the two lenses is such that a shape in a sub-scanning section thereof is a non-arc shape.

Abstract: An optical scanner includes a light source, an optical coupler, an optical line image unit, a deflector, and an optical scanning unit. The optical scanning unit includes scanning lenses that guide the beams to a surface to be scanned. A surface on the deflector side of the scanning lens closest to a deflection reflecting surface has a negative power in a vertical scanning direction, and is a special toric surface in which a radius of curvature in a vertical scanning changes from an optical axis of the lens surface toward a periphery of the horizontal scanning direction. An F number of the beams toward the surface to be scanned of the scanning lens in the vertical scanning direction is larger in a peripheral part than in a central part in an effective scanning width.

Abstract: An optical scanner includes a light source, an optical coupler, an optical line image unit, a deflector, and an optical scanning unit. The optical scanning unit includes scanning lenses that guide the beams to a surface to be scanned. A surface on the deflector side of the scanning lens closest to a deflection reflecting surface has a negative power in a vertical scanning direction, and is a special toric surface in which a radius of curvature in a vertical scanning changes from an optical axis of the lens surface toward a periphery of the horizontal scanning direction. An F number of the beams toward the surface to be scanned of the scanning lens in the vertical scanning direction is larger in a peripheral part than in a central part in an effective scanning width.