Abstract: A diffractive optical element that is used for an optical system includes a first diffraction grating and a second diffraction grating. The first and second diffraction gratings are disposed in contact with each other, one of the first and second diffraction gratings has a refractive index distribution and has a diffractive surface that includes a grating surface having a predetermined inclination and a grating wall surface having a predetermined height, and the diffractive surface has a shape in which an inclination of the grating surface of a diffraction grating having the greater refractive index distribution is decreased and a height of the grating wall surface is lowered with respect to a shape in which a phase difference based on a phase difference function that corrects an aberration of the optical system is added to a shape of a base surface that forms one of the first and second diffraction gratings.

Abstract: A diffractive optical element in which the maximum optical path length of light is an integral multiple of each of a plurality of wavelengths includes a diffractive grating configured by combining a first member and a second member having a refractive index lower than a refractive index of the first member and having dispersion higher than a dispersion of the first member. At least one of the first member and the second member is made of a glass material, and the diffractive grating is formed by the glass material which is heated to be softened using a thermal press forming, and has a concave grating shape that has a grating height increasing from a central part toward a peripheral part.

Abstract: A diffractive optical element that is used for an optical system includes a first diffraction grating and a second diffraction grating. The first and second diffraction gratings are disposed in contact with each other, one of the first and second diffraction gratings has a refractive index distribution and has a diffractive surface that includes a grating surface having a predetermined inclination and a grating wall surface having a predetermined height, and the diffractive surface has a shape in which an inclination of the grating surface of a diffraction grating having the greater refractive index distribution is decreased and a height of the grating wall surface is lowered with respect to a shape in which a phase difference based on a phase difference function that corrects an aberration of the optical system is added to a shape of a base surface that forms one of the first and second diffraction gratings.

Abstract: A diffractive optical element in which the maximum optical path length of light is an integral multiple of each of a plurality of wavelengths includes a diffractive grating configured by combining a first member and a second member having a refractive index lower than a refractive index of the first member and having dispersion higher than a dispersion of the first member. At least one of the first member and the second member is made of a glass material, and the diffractive grating is formed by the glass material which is heated to be softened using a thermal press forming, and has a concave grating shape that has a grating height increasing from a central part toward a peripheral part.

Abstract: The diffractive optical element is constituted by a glass material and a resin material whose dn/dT representing refractive index variation with temperature is larger than that of the glass material, the resin material being in close contact with or facing the glass material, and a diffractive grating formed at a close contact portion or a facing portion between the glass material and the resin material. The resin material is a mixture material of (a) a resin base material, (b) first fine particles formed of a first material whose dn/dT is equal to or higher than ?1×10?5(/° C.) and (c) second fine particles formed of a second material whose Abbe constant is lower than that of the glass material. The diffractive optical element can maintain high diffraction efficiency in a wide wavelength region even if temperature changes, without generating unnecessary diffracted light.

Abstract: Disclosed is an optical scanning apparatus for repeatedly optically scanning a plurality of surfaces to be scanned, including: a plurality of light sources; an optical deflector for deflecting and reflecting a plurality of light beams emitted from the plurality of light sources; and at least one scanning optical system for guiding the plurality of light beams which are deflected and reflected by the optical deflector to the different surfaces to be scanned. In the optical scanning apparatus, the plurality of light beams incident on the optical deflector are incident on a deflection surface of the optical deflector at different angles to a normal of the deflection surface, the scanning optical system is commonly used for the plurality of light beams, and the scanning optical system includes a first optical element that satisfies 0?|?1s|<0.001 where ?1s represents optical power of the scanning optical system within a sub scanning section.

Abstract: Disclosed is an optical scanning apparatus for repeatedly optically scanning a plurality of surfaces to be scanned, including: a plurality of light sources; an optical deflector for deflecting and reflecting a plurality of light beams emitted from the plurality of light sources; and at least one scanning optical system for guiding the plurality of light beams which are deflected and reflected by the optical deflector to the different surfaces to be scanned. In the optical scanning apparatus, the plurality of light beams incident on the optical deflector are incident on a deflection surface of the optical deflector at different angles to a normal of the deflection surface, the scanning optical system is commonly used for the plurality of light beams, and the scanning optical system includes a first optical element that satisfies 0?|?1s|<0.001 where ?1s represents optical power of the scanning optical system within a sub scanning section.

Abstract: Provided are an optical scanning apparatus, which keeps an oblique incident angle to be small with respect to a polygon mirror in a sub-scanning section to provide preferable optical performance with a compact and simple construction, and an image forming apparatus using the optical scanning apparatus. The optical scanning apparatus includes a plurality of light source means, an incident system turn back mirror that reflects light beams emitted from the plurality of light source means, a light deflector that deflects the plurality of light beams using the same deflecting surface, and an imaging optical system that guides the light beams deflected by the light deflector respectively onto a plurality of surfaces to be scanned. At the time of light-scanning of the plurality of surfaces to be scanned, the incident system turn back mirror is disposed in an effective scanning range in a main scanning section when it is projected in the main scanning section.

Abstract: Disclosed is an optical scanning apparatus for repeatedly optically scanning a plurality of surfaces to be scanned, including: a plurality of light sources; an optical deflector for deflecting and reflecting a plurality of light beams emitted from the plurality of light sources; and at least one scanning optical system for guiding the plurality of light beams which are deflected and reflected by the optical deflector to the different surfaces to be scanned. In the optical scanning apparatus, the plurality of light beams incident on the optical deflector are incident on a deflection surface of the optical deflector at different angles to a normal of the deflection surface, the scanning optical system is commonly used for the plurality of light beams, and the scanning optical system includes a first optical element that satisfies 0?|?1s|<0.001 where ?1s represents optical power of the scanning optical system within a sub scanning section.

Abstract: Provided is an optical scanning apparatus for optically scanning a surface to be scanned, including: a light source unit that emits a beam modulated according to an image signal; a condenser lens for temporarily focusing the beam emitted from the light source unit into an image in a sub-scanning section in the vicinity of a deflection surface of a light deflector; and a scanning optical system for guiding the beam deflected by the light deflector onto the surface to be scanned, in which: in the sub-scanning section, the beam from the condenser lens is incident at an angle with a normal to the deflection surface; and an scanning optical element constituting the scanning optical system has an optical axis eccentric toward a deflection point side of the deflection surface with respect to a transmission position of a principle ray of the beam in a sub scanning direction.

Abstract: Provided are an optical scanning apparatus, which keeps an oblique incident angle to be small with respect to a polygon mirror in a sub-scanning section to provide preferable optical performance with a compact and simple construction, and an image forming apparatus using the optical scanning apparatus. The optical scanning apparatus includes a plurality of light source means, an incident system turn back mirror that reflects light beams emitted from the plurality of light source means, a light deflector that deflects the plurality of light beams using the same deflecting surface, and an imaging optical system that guides the light beams deflected by the light deflector respectively onto a plurality of surfaces to be scanned. At the time of light-scanning of the plurality of surfaces to be scanned, the incident system turn back mirror is disposed in an effective scanning range in a main scanning section when it is projected in the main scanning section.

Abstract: Disclosed is an optical scanning apparatus for repeatedly optically scanning a plurality of surfaces to be scanned, including: a plurality of light sources; an optical deflector for deflecting and reflecting a plurality of light beams emitted from the plurality of light sources; and at least one scanning optical system for guiding the plurality of light beams which are deflected and reflected by the optical deflector to the different surfaces to be scanned. In the optical scanning apparatus, the plurality of light beams incident on the optical deflector are incident on a deflection surface of the optical deflector at different angles to a normal of the deflection surface, the scanning optical system is commonly used for the plurality of light beams, and the scanning optical system includes a first optical element that satisfies 0?|?1 s|<0.001 where ?1 s represents optical power of the scanning optical system within a sub scanning section.

Abstract: Provided is an optical scanning apparatus for optically scanning a surface to be scanned, including: a light source unit that emits a beam modulated according to an image signal; a condenser lens for temporarily focusing the beam emitted from the light source unit into an image in a sub-scanning section in the vicinity of a deflection surface of a light deflector; and a scanning optical system for guiding the beam deflected by the light deflector onto the surface to be scanned, in which: in the sub-scanning section, the beam from the condenser lens is incident at an angle with a normal to the deflection surface; and an scanning optical element constituting the scanning optical system has an optical axis eccentric toward a deflection point side of the deflection surface with respect to a transmission position of a principle ray of the beam in a sub scanning direction.

Abstract: An optical scanning apparatus has an incident optical system for causing a light beam from a light source to be obliquely incident in a sub-scanning cross-section on a deflecting surface of an optical deflector, and an imaging optical system for forming, on a scanned surface, an image of the light beam deflected by the deflecting surface.

Abstract: An image forming apparatus which includes a light source for emitting a light beam modulated according to an image signal and an optical deflector for repeatedly deflecting the light beam. A focussing optical system focuses the light beam deflected by the optical deflector on a surface to be scanned to form a light spot there, the surface being scanned repeatedly in a main-scanning direction. A photosensitive member is arranged at the surface and exposed selectively to the light spot, the photosensitive member having an image forming region and blank regions arranged at opposite ends of the image forming region. A developing unit causes toner to adhere to unexposed areas of the selectively exposed photosensitive member and develops an image. A photodetector receives part of the light beam emitted from the light source and an automatic power control circuit controls an output power of the light source on the basis of an output of the photodetector.

Abstract: Reflected light from a surface not associated with an image is efficiently cut while maintaining rays in a portion associated with formation of an image in a polygon mirror. Among light guided to the polygon mirror by an incidence optical system, a beam indicated by hatching is incident to an f&thgr; lens, is reflected by an unrepresented cylindrical mirror, and forms a spot on the image plane to scan the surface with rotation of the polygon mirror. Since the beam incident to the polygon mirror is greater than the width of polygon facets, there exists a beam reflected by an adjacent facet. In order to intercept this beam, a shield member is placed in a certain determined range between the f&thgr; lens and the facet of the polygon mirror, so as to cut unwanted flare.

Abstract: An optical scanning apparatus includes a light source having a plurality of light-emitting portions arranged as inclined with respect to a main scanning direction, a deflector for deflecting a plurality of light beams emitted from the light source, an imaging system for guiding the plurality of light beams deflected and reflected by the deflector, onto a scanned surface, a detector arranged substantially at the same position as the scanned surface and in a normal direction to the main scanning direction. The detector detects scanning positions of the plurality of light beams and a difference between pass times of the plurality of light beams to thereby detect deviation of the scanning positions and variation of magnification of the optical scanning apparatus. A correcting device is provided for correcting drawing positions of the plurality of light beams on the scanned surface, based on the result of detection by the detector.

Abstract: An optical scanning apparatus has an incident optical system for causing a light beam from a light source to be obliquely incident in a sub-scanning cross-section on a deflecting surface of an optical deflector, and an imaging optical system for forming, on a scanned surface, an image of the light beam deflected by the deflecting surface.

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: A zoom lens of the retrofocus type includes, in order from a longer-distance conjugate point side to a shorter-distance conjugate point side, a front lens unit of negative refractive power, and a rear lens unit of positive refractive power, wherein a separation between the front lens unit and the rear lens unit varies according to variation of magnification, and at least one of the front lens unit and the rear lens unit is provided with a diffractive optical element.