Abstract: Disclosed is an optical scanning device which includes a light source device, a deflecting system for deflecting a light beam emitted from the light source device, and a scanning optical system for scanning a surface to be scanned, with the light beam deflected by the deflecting system, wherein the scanning optical system includes a scanning optical element disposed so that, with respect to a sub-scan direction, a principal ray of the deflected light beam passes a portion other than an optical axis, wherein the scanning optical element has a sagittal aspherical amount changing surface in which an aspherical amount of a sagittal changes along a main scan direction of the scanning optical element, and wherein, throughout the whole surface to be scanned, the position in the sub-scan direction upon which the deflected light beam impinges is made even.

Abstract: A color image reading apparatus comprises at least three line sensors arranged at regular intervals along the main scanning direction, an imaging optical system for focussing a light beam on the line sensors, and a diffraction grating for separating a light beam coming from a color image into a plurality of light beams having respective wavelengths different from each other. The imaging optical system includes at least one lens and the optical axis of the lens is eccentrically disposed relative to that of the optical system as a whole so as for the plurality of light beams to be focussed on the respective line sensors.

Abstract: This invention relates to an image reading apparatus which eliminates color misregistration upon reading in the sub-scanning direction, which occurs due to different afterglow or persistence characteristics of the respective colors of a light source upon executing the light quantity control of the light source for illuminating an original. Since the light quantity control of the light source is divisionally done a plurality of times in one accumulation period of a solid-state image sensing element, any deviation of the center of gravity in the quantity of light from the center C of one accumulation period can be minimized, and the color misregistration can be eliminated remarkably.

Abstract: An imaging element includes a diffraction optical element on which an off-axis beam with a field angle is incident and a stop. Of beams having different field angles and incident on the diffraction optical element, beams having incident angles larger than the incident angle of a principal light ray of the beams incident on the grating surface of the diffraction optical element are partially shielded by a light-shielding member, so that the diffraction efficiencies of orders adjacent to a design order are kept low and hence imaging performance almost free from flare can be achieved even if a beam with a field angle is incident.

Abstract: An optical scanning apparatus includes a light source unit, a deflecting unit for deflecting and scanning a light beam from the light source unit, and a scanning optical system for scanning the light beam deflected by the deflecting unit on a surface to be scanned. The scanning optical system includes a diffraction portion having an aspherical function in a sub-scanning direction.

Abstract: A laminate-type diffractive optical element which is easily producible and which allows high optical performance to be easily achieved, and an optical system using the same, are disclosed. In the diffractive optical element formed by laminating a plurality of diffraction gratings, when the distance between the uppermost portion of one diffraction grating and the lowermost portion of the other diffraction grating in two diffraction gratings adjacent to each other along the incident direction of a light is represented by D (&mgr;m), these two diffraction gratings are arranged to satisfy the following relation: 10 &mgr;m<D<40 &mgr;m.

Abstract: An object of the present invention is to provide a scanning optical apparatus that is capable of suppressing, to a minute amount, scanning line bending caused by rotational decentration of a single lens that is a scanning optical system, and to provide an image forming apparatus using the optical scanning apparatus. To achieve the stated object, with the technique of the present invention, a single lens is used as a scanning optical system and the surface shape of the single lens is set so that a direction of scanning line bending in the sub scanning direction occurring when an incident surface of the single lens is rotationally decenter about an axis parallel to the main scanning direction is opposite to a direction of scanning line bending in the sub scanning direction occurring when an exit surface is rotationally decenter about the axis parallel to the main scanning direction.

Abstract: This invention relates to an image reading apparatus which eliminates color misregistration upon reading in the sub-scanning direction, which occurs due to different afterglow or persistence characteristics of the respective colors of a light source upon executing the light quantity control of the light source for illuminating an original. Since the light quantity control of the light source is divisionally done a plurality of times in one accumulation period of a solid-state image sensing element, any deviation of the center of gravity in the quantity of light from the center C of one accumulation period can be minimized, and the color misregistration can be eliminated remarkably.

Abstract: It is an object of this invention to provide a light scanning device capable of suppressing scanning line bending to a low level, which is caused by the arrangement error of a single-element lens serving as an imaging optical element, and an image forming apparatus using the device. In order to achieve the object, according to this invention, an imaging optical system is formed from a single-element lens, and the sectional shapes of the incident and exit surfaces in the main scanning direction are non-arcuated, and the power in the sub scanning direction substantially concentrates on the exit surface. The non-arcuated shape (curvature) of the exit surface in the main scanning direction is so determined as to make the magnification in the sub scanning direction uniform.

Abstract: Disclosed is a scanning optical device and an image forming apparatus using the same, wherein the scanning optical device includes a scanning optical element provided by a single lens.

Abstract: An object of the present invention is to provide a scanning optical apparatus that is capable of suppressing, to a minute amount, scanning line bending caused by rotational decentration of a single lens that is a scanning optical system, and to provide an image forming apparatus using the optical scanning apparatus. To achieve the stated object, with the technique of the present invention, a single lens is used as a scanning optical system and the surface shape of the single lens is set so that a direction of scanning line bending in the sub scanning direction occurring when an incident surface of the single lens is rotationally decenter about an axis parallel to the main scanning direction is opposite to a direction of scanning line bending in the sub scanning direction occurring when an exit surface is rotationally decenter about the axis parallel to the main scanning direction.

Abstract: It is an object of this invention to provide a light scanning device capable of suppressing a scanning line bend to a low level, which is caused by the arrangement error of a single-element lens serving as an imaging optical element, and an image forming apparatus using the device. In order to achieve the object, according to this invention, an imaging optical system is formed from a single-element lens, and a sectional shape of an exit surface in the main scanning direction is an arcuated shape. The power in the sub scanning direction substantially concentrates on the exit surface having an arcuated sectional shape in the main scanning direction, and the arcuated shape (curvature) in the main scanning direction is so determined as to make the magnification in the sub scanning direction uniform.

Abstract: An optical system provided with a lens, a stop and a diffraction grating is characterized in that when in a state wherein the diffraction grating is absent, the value of the coefficient of chromatic aberration of magnification of the wavelength of the long wavelength side relative to the reference wavelength of light is positive, the diffraction grating is disposed more adjacent to an incidence surface side than the stop, and when in the state wherein the diffraction grating is absent, the value of the coefficient of chromatic aberration of magnification of the wavelength of the long wavelength side relative to the reference wavelength of the light is negative, the diffraction grating is disposed more adjacent to an emergence side than the stop.

Abstract: A scanning optical system using a short-wavelength light of 500 nm or less uses a reflecting mirror having a higher absolute reflectivity and having reduced wavelength and angle dependences. Divergent ray of light emitted from a semiconductor laser is converted into an approximately parallel light beam by a collimator lens and the diameter of the light flux is reduced by an aperture before travel to a polygon mirror. The light beam from the polygon mirror passes through scanning lenses to form a small spot at any point in the entire scanning area. The semiconductor laser is a gallium nitride semiconductor laser having an oscillation wavelength of 408 nm. The polygon mirror has such a characteristic that, if the complex refractive index N of a metallic film contributing to a reflection characteristic of the reflecting mirror is defined as N(&lgr;)=n(&lgr;)−ik(&lgr;), then k(&lgr;)>{square root}{square root over ((−n(&lgr;)2+18n(&lgr;)−1))} is satisfied.

Abstract: An image sensing device includes: a light source, a recording member on which an image is formed and conveyed in one direction, illumination system for causing a light beam emitted from the light source to obliquely illuminate the recording member and, imaging system for condensing specularly reflected light from the image on the recording member and causing the reflected light to travel to a surface of a photodetector, so that the image sensing device obtains positional information of the image on the recording member on the basis of a signal obtained by the photodetector.

Abstract: An imaging element includes a diffraction optical element on which an off-axis beam with a field angle is incident and a stop. Of beams having different field angles and incident on the diffraction optical element, beams having incident angles larger than the incident angle of a principal light ray of the beams incident on the grating surface of the diffraction optical element are partially shielded by a light-shielding member, so that the diffraction efficiencies of orders adjacent to a design order are kept low and hence imaging performance almost free from flare can be achieved even if a beam with a field angle is incident.

Abstract: A laminate-type diffractive optical element which is easily producible and which allows high optical performance to be easily achieved, and an optical system using the same, are disclosed. In the diffractive optical element formed by laminating a plurality of diffraction gratings, when the distance between the uppermost portion of one diffraction grating and the lowermost portion of the other diffraction grating in two diffraction gratings adjacent to each other along the incident direction of a light is represented by D (&mgr;m), these two diffraction gratings are arranged to satisfy the following relation: 10 &mgr;m<D<40 &mgr;m.

Abstract: An object of the present invention is to provide an image forming apparatus that has a light source, deflecting device for deflecting light emitted from the light source by a rotation, a mirror for deflecting the light deflected by the deflecting device, an image bearing body to which the light deflected by the mirror is irradiated, and a lens for image-forming the light deflected by the deflecting device onto the image bearing body, wherein a plurality of lights are deflected by the one deflecting device and only the one mirror exists in an optical path along which the one light deflected by the deflecting device reaches the image bearing body.

Abstract: In an image reading apparatus having an easy-toad-just optical system, a unit is composed of a first sub-unit including an image forming lens and a second sub-unit including a solid-state image pickup element. The first sub-unit and the second sub-unit are mutually adjusted in position in X-axis, Y-axis and Z-axis while the two sub-units are also adjustable around X-axis and Z-axis. After the first sub-unit and the second sub-unit are adjusted using a tool, the unit is then assembled into the apparatus. The unit is rotated around an optical axis of the image forming lens for adjustment of perpendicularity. The unit is also rotated around a line direction of the solid-state image pickup element for adjustment of scanning synchronization (the reading position in a sub-scan direction).

Abstract: In a color image reading apparatus, a plurality of line sensors are arranged on a same substrate and an image of an object is formed on the sensors by an imaging optical system. A blazed diffraction grating is disposed in an optical path between the imaging optical system and the sensors so as to color-separate a light beam from the object into a plurality of color light beams. A correction element such as a plane-parallel glass, prism or the like is disposed in an optical path between the blazed diffraction grating and the sensors so as to correct different imaging positions on the surfaces of the sensors caused by different wavelengths of the plurality of color light beams color-separated by the blazed diffraction grating.