Abstract: A focus detection optical system includes a condenser lens positioned behind an expected image plane of a photographing lens, an auxiliary lens positioned behind the condenser lens, and a separator lens including a pair of lenses behind the auxiliary lens. An object image formed on the expected image plane is divided into two images by the pair of lenses and reformed on a pair of areas on a sensor. The auxiliary lens is a plastic lens having a negative refractive power. The separator lens is a glass lens or a hybrid lens consisting of a glass substrate and a plastic lens having a curved surface which is layered onto the glass substrate, and the focus detection optical system satisfies the following condition (1): 0.068<m1/m2<0.090??(1), wherein m1 and m2 designate magnifications of first and second surfaces, respectively, of the auxiliary lens.

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: 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: A focus detection optical system includes a condenser lens positioned behind an expected image plane of a photographing lens, an auxiliary lens positioned behind the condenser lens, and a separator lens including a pair of lenses behind the auxiliary lens. An object image formed on the expected image plane is divided into two images by the pair of lenses and reformed on a pair of areas on a sensor. The auxiliary lens is a plastic lens having a negative refractive power. The separator lens is a glass lens or a hybrid lens consisting of a glass substrate and a plastic lens having a curved surface which is layered onto the glass substrate, and the focus detection optical system satisfies the following condition (1): 0.068<m1/m2<0.090??(1), wherein m1 and m2 designate magnifications of first and second surfaces, respectively, of the auxiliary lens.

Abstract: A scanning lens for an imaging optical system converges a beam emitted by a light source and deflected by a deflector on a target surface to form a beam spot scanning in a main scanning direction thereon. The scanning lens includes a plastic lens formed by injection molding, which has a diffractive lens structure on at least one surface thereof. The diffractive lens structure has a plurality of annular zones arranged concentrically about a rotational axis. Each annular zone has a diffracting surface that diffracts the light beam passing therethrough. The diffractive lens structure has stepped surfaces each connecting adjoining diffracting surfaces. In a plane including the rotational axis and parallel with the main scanning direction, the stepped surfaces are inclined with respect to the rotational axis so that stress working between a metallic molding for the plastic lens and each of the stepped surfaces in demolding is reduced.

Abstract: An apparatus for detecting a focus state has an optical image-forming system that forms an object image, a plurality of line sensors that is arranged on a projected area of the optical image-forming system; a plurality of monitor sensors that is arranged on the projected area along the direction of a line-sensor array, each monitor sensor being adjacent to a corresponding line sensor and monitoring an amount of light incident on the corresponding line sensor; and a signal processor that outputs image-pixel signals corresponding to the object image on the basis of electric charges accumulated in the plurality of line sensors. At least an endmost monitor sensor corresponding to an endmost line sensor is arranged on the center-facing side of the endmost line sensor.

Abstract: A scanning optical system is provided with a light source configured to emit a plurality of beams, a deflecting device configured to deflect the plurality of beams simultaneously to scan in a main scanning direction, and an imaging optical system configured to converge the plurality of beams on a plurality of target surfaces to form a plurality of beam spots scanning on the plurality of target surfaces, respectively.

Abstract: There is provided a scanning optical system, which is provided with a light source that emits at least one beam, a polygonal mirror, and an imaging optical system that converges the at least one beam deflected by the polygonal mirror to form at least one beam spot on a surface to be scanned. The at least one beam incident on the polygonal mirror is inclined in an auxiliary scanning direction which is perpendicular to the main scanning direction. Further, at least one lens surface of the imaging optical system is configured such that a beam reflected therefrom proceeds toward an outside region of the polygonal mirror.

Abstract: A scanning lens for an imaging optical system converges a beam emitted by a light source and deflected by a deflector on a target surface to form a beam spot scanning in a main scanning direction thereon. The scanning lens includes a plastic lens formed by injection molding, which has a diffractive lens structure on at least one surface thereof. The diffractive Wens structure has a plurality of annular zones arranged concentrically about a rotational axis. Each annular zone has a diffracting surface that diffracts the light beam passing therethrough. The diffractive lens structure has stepped surfaces each connecting adjoining diffracting surfaces In a plane including the rotational axis and parallel with the main scanning direction, the stepped surfaces are inclined with respect to the rotational axis so that stress working between a metallic molding for the plastic lens and each of the stepped surfaces in demolding is reduced.

Abstract: A scanning optical system is provided with a light source configured to emit a plurality of beams, a deflecting device configured to deflect the plurality of beams simultaneously to scan in a main scanning direction, and an imaging optical system configured to converge the plurality of beams on a plurality of target surfaces to form a plurality of beam spots scanning on the plurality of target surfaces, respectively.

Abstract: A scanning optical system comprises: a light source which emits a beam of light; a deflecting system that dynamically deflects the beam emitted by the light source with its deflecting surface; and a scan lens group including a molded resin lens, which focuses the beam dynamically deflected and scanned in a main scanning direction by the deflecting system on an image formation surface. In the scanning optical system, the molded resin lens has a diffracting lens surface which is provided with a diffractive level difference structure formed on a base curve having refractive power, and a following condition is satisfied: 18<WL/P<28 where “W” denotes an effective scan width (mm) on the image formation surface, “L” denotes a distance (mm) from the deflecting surface to the molded resin lens, and “P” denotes a distance (mm) from the deflecting surface to the image formation surface.

Abstract: In a scanning optical system, a plurality of laser beams pass through an imaging optical system and converge on surfaces to be scanned, respectively. The imaging optical system includes a scanning lens and a plurality of long lenses for the respective beams. The scanning lens has an anamorphic aspherical surface, and each long lens has at least one two-dimensional polynomial aspherical surface. A following relationship is optionally satisfied: ?<0.15?0.2?/N, where, ? denotes an absolute value of the incident angle (rad.) of the outermost one of the plurality of laser beams incident on the reflection surface in the auxiliary scanning direction, ? denotes a half field angle (rad.) representing the maximum inclination angle of the laser beam with respect to the reference axis of the scanning lens group in the main scanning direction, and N denotes the number of surfaces of the long lenses employing the two-dimensional polynomial aspherical surface.

Abstract: A scanning optical system comprises: a light source which emits a beam of light; a deflecting system that dynamically deflects the beam emitted by the light source with its deflecting surface; and a scan lens group including a molded resin lens, which focuses the beam dynamically deflected and scanned in a main scanning direction by the deflecting system on an image formation surface. In the scanning optical system, the molded resin lens has a diffracting lens surface which is provided with a diffractive level difference structure formed on a base curve having refractive power, and a following condition is satisfied: 18<WL/P<28 where “W” denotes an effective scan width (mm) on the image formation surface, “L” denotes a distance (mm) from the deflecting surface to the molded resin lens, and “P” denotes a distance (mm) from the deflecting surface to the image formation surface.

Abstract: A scanning optical system includes a light source that emits a plurality of beams, a polygonal mirror that deflects the plurality of beams emitted by the light source to scan within a predetermined angular range, and an imaging optical system that converges the plurality of beams on a plurality of surfaces to be scanned, respectively. The imaging optical system includes a scanning lens and a plurality of compensation lenses located between the scanning lens and a plurality of surfaces to be scanned. The plurality of beams passed through the scanning lens are incident on the plurality of compensation lenses, respectively. Each of the plurality of compensation lenses having an anamorphic surface, shapes of which in a main scanning direction are substantially the same with respect to each other.

Abstract: A scanning optical system is provided with a light source, a polygonal mirror, and an imaging optical system that converges the at least one beam deflected by the polygonal mirror. The imaging optical system has a scanning lens, and a compensation lens. The light source is arranged so that beams emitted by the light source are incident on the polygonal mirror from the outside of the predetermined scanning range in the main scanning direction and are incident on the polygonal mirror being inclined in an auxiliary scanning direction with respect to a plane perpendicular to a rotational axis of the polygonal mirror. Further, at least one surface of the scanning lens has a first anamorphic surface, power of the first anamorphic surface in the auxiliary scanning direction is distributed asymmetrically in the main scanning direction with respect to an optical axis of said scanning lens.

Abstract: A laser beam emitted by a light source is incident on one of reflecting surfaces of a polygon mirror. The laser beam reflected by the reflecting surface is dynamically deflected in a main scanning direction due to the revolution of the polygon mirror and enters a scanning lens. The first surface of the scanning lens is provided with anti-reflection coating only when the following condition (1) is satisfied: H/2>|2?D(D?Rz1)/Rz1|??(1) where “H” denotes the width of each reflecting surface of the polygon mirror in a auxiliary scanning direction, “?” denotes the incident angle [radian] of the laser beam on the reflecting surface of the polygon mirror in the auxiliary scanning direction, “D” denotes the distance between the reflecting surface and the first surface of the scanning lens, and “Rz1” denotes the curvature radius of the first surface in an auxiliary scanning cross section.

Abstract: There is provided a scanning optical system which includes a light source, a line-like image forming optical system, a polygonal mirror, and an imaging optical system. The line-like image forming optical system forms a line-like image extending in the main scanning direction in the vicinity of a reflective surface of the polygonal mirror, and if the number of reflective surfaces of the polygonal mirror is less than or equal to six and if |m|>1.85, the following condition (1) is satisfied: r<5 cos(w/2f)/[2|m|{1? cos(w/2f)}]??(1) where r represents a radius of an inscribed circle of the polygonal mirror, m represents a lateral magnification of the imaging optical system in the auxiliary scanning direction, f represents a focal length of the imaging optical system in the main scanning direction, and w represents half of a scanning width.

Abstract: A projection optical system, which is telecentric with respect to an object side and an image side, projects a pattern onto an image plane, which is substantially parallel with the pattern, at a substantial equi-magnification. The projecting optical system is provided with first and second condenser lenses having a common (first) optical axis which is perpendicular to the pattern and the image plane. The projection optical system further includes an imaging lens having a second optical axis that intersects with the first optical axis at an intermediate position between the first and second condenser lenses. A first mirror reflects a beam from the pattern and passed through the first condenser lens toward the imaging lens. A second mirror reflects the beam passed through the imaging lens to the imaging lens, and a third mirror reflects the beam passed through the imaging lens toward the second condenser lens.

Abstract: A scanning optical system deflects a light beam by a reflection surface of a polygon mirror toward an object surface through an image forming optical system so that the light beam scans on the object surface to form an image thereon. A light shielding member is disposed between the polygon mirror and the image forming optical system. The shielding member is an opaque plate disposed perpendicular to the optical axis of the image forming optical system. The light shielding member prevents a ghost light that is reflected by another reflection surface of the polygon mirror located adjacent to the reflection surface deflecting the light beam from entering the image forming optical system and impinging onto the object surface.