Abstract: A phase shift element having a central area (for transmitting part of an incident laser beam in the vicinity of the beam central axis) and a first area (giving the laser beam incident thereon a phase difference ? relative to a beam passing through the central area) is placed on an optical path between a laser light source and a polygon mirror of a scanning optical system. The scanning optical system including such a phase shift element is installed in a printer. By the effect of the phase shift element, the intensity of side lobes (several rings of light accompanying the main beam) is prevented from exceeding a threshold value even when optical surfaces of an imaging optical system of the scanning optical system have certain microscopic undulations, by which black stripes occurring in halftone printing can be eliminated.

Abstract: A scanning optical system is configured to include a light source, an anamorphic optical element, a polygonal mirror, and an imaging optical system. The imaging optical system has a scanning lens including a first lens provided on a polygonal mirror side and a second lens provided on a surface side, and a compensation lens provided on the surface side with respect to the scanning lens, the compensation lens compensating for curvature of field. The scanning lens includes at least one convex surface that has a toric surface having a stronger power in the auxiliary scanning direction than in the main scanning direction. One surface of the compensation lens has an anamorphic aspherical surface, which is a surface whose radius of curvature in the auxiliary scanning direction at a point spaced from the optical axis thereof is determined independently from a cross-sectional shape thereof along the main scanning direction.

Abstract: A scanning optical system includes a light source, an anamorphic optical element, a polygonal mirror, and an imaging optical system that converges the beam(s) on a surface to be scanned. The imaging optical system has a scanning lens, and a compensation lens provided on the surface side for compensating for curvature of field. All the surfaces of the scanning lens are rotationally symmetrical, and the compensation lens has an aspherical surface. A cross section of the aspherical surface in the auxiliary scanning direction is asymmetrical with respect to the optical axis thereof, and a SAG amount defining the aspherical surface is expressed by a two-dimensional polynomial.

Abstract: A scanning optical system includes a polygonal mirror that deflects the even number of beams, which are incident thereon along optical paths arranged symmetrically with respect to a plane perpendicular to a rotation axis thereof. An imaging optical system for converging the beams includes lenses for converging the beam, in an auxiliary scanning direction, respectively. The lenses have the same shapes, and are arranged symmetrically with respect to the plane. The orientation of the lenses on one side of the plane is oriented oppositely, in the auxiliary scanning direction, to the other lenses located on the other side of the plane.

Abstract: An objective lens for recording data to and/or reproducing data from first and second optical discs. The objective lens is provided with at least one surface including a plurality of annular zones divided by steps. The steps has functions of phase shifting a wavefront of light passing through the plurality of annular zones so that a beam spot formed at a converging point of an average wavefront of the wavefront phase shifted by the steps is used for the first and second optical discs. The plurality of annular zones of the at least one surface includes at least one annular zone structure which includes first and second annular zone groups, each of which has at least three steps for phase shifting the wavefront in a first direction, and a first return step which is a step formed at a boundary between the first and second annular zone groups. The first return step phase shifts the wavefront in a second direction opposite to the first direction.

Abstract: A tandem type printer is provided with a plurality of scanning optical systems, a plurality of f? lenses and photoconductive drums, which correspond to the scanning optical systems, respectively. Each scanning optical system includes a laser source and a deflector that deflects the laser beam emitted by the laser source to scan, in a main scanning direction, within a predetermined angular range. The deflected laser beam is converged by the f? lens on the corresponding photoconductive drum and form an image. Images formed on the plurality of photoconductive drums are developed and transferred on a sheet in an overlaid fashion. Each f? lens includes a glass lens that is burdened with substantially all the power, in the main scanning direction, of the f? lens, and a plastic lens that is burdened with compensation for aberrations of the f? lens. Further, a diffraction lens structure is formed to compensate for a lateral chromatic aberration of the f? lens in the main scanning direction.

Abstract: An optical system of an optical pick-up for a plurality of types of optical discs with a corresponding plurality of light sources. A first coupling lens that is used at least for the first optical disc, and an objective lens that is used for the plurality of types of optical discs. A beam for the first optical disc emitted by the plurality of light sources passes through the first coupling lens and is incident on the objective lens as a diverging beam. The diverging beam being given spherical aberration by the coupling lens. When the objective lens shift occurs, a coma component relating to the spherical aberration of the diverging beam which is shifted with respect to the objective lens due to the shift of the objective lens is canceled by a coma generated by the objective lens and the cover layer of the first optical disc.

Abstract: There is provided an objective lens for an optical pick-up which is used to record/reproduce data to/from at least three types of optical discs. Thicknesses t1, t2 and t3 of cover layers of first, second third optical discs are t1?0.6 mm, t2?0.6 mm, and t3?1.2 mm. Numerical apertures NA1, NA2 and NA3 for the first, second and third optical discs satisfy a relationship NA1?NA2>NA3. When the first optical disc is used, a substantially collimated light beam is incident on the objective lens. When the second or third optical disc is used, a diverging beam is incident on the objective lens. With regard to magnifications M1, M2 and M3 and focal lengths f1, f2 and f3 of the objective lens for the first, second and third optical discs, the following conditions (1), (2) and (3) are satisfied: ?0.02<f1×M1<0.02??(1) ?0.10<f2×M2<?0.04??(2) ?0.29<f3×M3<?0.19??(3).

Abstract: An objective lens used for recording data to and/or reproducing data from a plurality of types of optical discs having different thicknesses of cover layers. The objective lens satisfies a condition 0.02<M2?M1<0.15, where M1 represents a magnification of the objective lens when recording/reproducing for a first optical disc is performed using the first light beam, and M2 represents a magnification of the objective lens when the recording/reproducing for a second optical disc is performed using the second light beam. Further, at least one of lens surfaces of the objective lens is provided with a diffracting structure having a plurality of annular zones configured to correct spherical aberrations for both of the first and second optical discs.

Abstract: An objective lens on which a beam having parallel light fluxes is incident includes a single element lens and a reflection suppressing coating formed on at least one surface of the single element lens. The reflection suppressing coating is formed such that the reflectivity across a radius of the objective lens exhibits a local maximal value, and the reflection suppressing coating is formed to achieve the following condition: 0.6<h1/hmax<0.95, wherein h1 denotes a distance between an optical axis and a position at which the reflectivity exhibits the local maximal value, and hmax denotes a distance between the optical axis and an outermost position of the effective diameter of the objective lens.

Abstract: There is provided an objective lens used for a plurality of types of optical discs having a front surface and a rear surface, each of which includes an inner region and an outer region. The outer region has a surface shape which suppresses a coma caused when a beam used for a first optical disc is incident thereon obliquely with respect to an optical axis of the objective lens. The inner region is configured such that, at a boundary position between the inner region and the outer region, the coma caused when a beam used for a second optical disc is incident on the inner region obliquely at a first angle with respect to the optical axis is less than the coma caused when the beam used for the second optical disc is incident on the outer region obliquely at the first angle with respect to the optical axis. Further, an inclination ?2A of the inner region and an inclination ?2B of the outer region of the rear surface satisfy a condition: ?2.5<?2B??2A<0.0??(1).

Abstract: A complex lens for a tandem scanning optical system converges a plurality of light beams, which are modulated independently and deflected by a deflector, onto a surface to be scanned, and forms a plurality of scanning lines at the same time. The complex lens includes a plurality of stacked lens portions that are molded as a single-piece element. Thus a plurality of lens surfaces of the lens portions at an incident side are formed by a single-piece mirror surface core and a plurality of lens surfaces of the lens portions at an exit side are formed by another single-piece mirror surface core during the molding process.

Abstract: An objective lens that satisfies conditions: ?0.02<f1×M1<0.02??(1) ?0.02<f2×M2<0.02??(2) ?0.29<f3×M3<?0.19??(3). At least one of lens surfaces of the objective lens includes a diffracting structure having a first region for converging the third light beam on a data recording layer of the third optical disc. The diffracting structure within the first region is configured such that a diffraction order at which diffraction efficiency of the first light beam is maximized is a sixth order, a diffraction order at which the diffraction efficiency of the second light beam is maximized is a fourth order, and a diffraction order at which the diffraction efficiency of the third light beam is maximized is a third order.

Abstract: There is provided an objective lens used for at least three types of optical discs. When thicknesses of a first, second and third optical discs are respectively represented by t1, t2 and t3, t1 is 0.6 mm, t2 is 0.6 mm, and t3 is 1.2 mm. When numerical apertures for the first, second and third optical discs are respectively represented by NA1, NA2 and NA3, a relationship NA1≧NA2>NA3 is satisfied. When the first and second optical discs are used, collimated light beams is incident on the objective lens. When the third optical disc is used, a diverging beam is incident on the objective lens. The following conditions are satisfied: −0.02<f1×M1<0.02 . . . (1), −0.02<f2×M2<0.02 . . . (2), and −0.29<f3×M3<−0.19 . . . (3). The objective lens includes a diffracting structure having a first region.

Abstract: An objective lens for an optical pickup has a single lens element. One surface of the objective lens is divided into a central area and a peripheral area, and a step providing a level difference along a direction of the optical axis is formed at a boundary therebetween. The step provides a phase shift between light passing through the central area and the peripheral area. The level difference is formed such that a thickness on the peripheral area side is greater than a thickness on the central area side at the boundary. In one case, the objective lens satisfies a condition: 0.83<hx/hmax<0.97, where hx is a radius of the boundary, and hmax is an effective radius defining a numerical aperture of the surface formed with the step.

Abstract: In a scanning optical system, a partial light blocking member having an annular light blocking part (for blocking off part of the incident laser beam entering the annular area around the central axis of the laser beam) is placed on an optical path between the laser light source and the polygon mirror. The scanning optical system including such a partial light blocking member is installed in a printer. By the effect of the partial light blocking member, the intensity of side lobes (several rings of light accompanying the main beam) is prevented from exceeding a threshold value even when optical surfaces of an imaging optical system of the scanning optical system have certain microscopic undulations, by which black stripes occurring in halftone printing can be eliminated.

Abstract: Disclosed is a manufacturing method of a complex lens for a tandem scanning optical system that includes a step for preparing molding dies for forming a cavity to form the complex lens as a single-piece element, and a step for injecting lens material into the cavity. The molding dies include a pair of single-piece mirror surface cores that form a plurality of lens surfaces of the complex lens at an incident side and a plurality of lens surfaces at an exit side, respectively. The complex lens has a plurality of stacked lens portions and the lens portions converging a plurality of light beams, which are modulated independently and deflected by a deflector, onto a surface to be scanned, respectively, for forming a plurality of scanning lines at the same time.

Abstract: A scanning optical system includes a polygonal mirror that deflects the even number of beams, which are incident thereon along optical paths arranged symmetrically with respect to a plane perpendicular to a rotation axis thereof. An imaging optical system for converging the beams includes lenses for converging the beam, in an auxiliary scanning direction, respectively. The lenses have the same shapes, and are arranged symmetrically with respect to the plane. The orientation of the lenses on one side of the plane is oriented oppositely, in the auxiliary scanning direction, to the other lenses located on the other side of the plane.

Abstract: Disclosed is a scanning optical system that includes a laser source for emitting a laser beam, a scanning deflector that deflects the laser beam, an imaging optical system that converges the scanning laser beam onto an object surface, first and second mirrors that bend the optical path of the scanning laser beam. The first and second mirrors are movable to adjust the optical path length between the deflector and the object surface for changing a width of the scanning range on the object surface. Since the optical path length is adjusted by moving the first and second mirror, which changes the width of the scanning range, correcting the size error of the printed image. When the size error of the printed image is detected, an operator moves the first and second mirrors to correct it.

Abstract: A phase shift element having a central area (for transmitting part of an incident laser beam in the vicinity of the beam central axis) and a first area (giving the laser beam incident thereon a phase difference &pgr; relative to a beam passing through the central area) is placed on an optical path between a laser light source and a polygon mirror of a scanning optical system. The scanning optical system including such a phase shift element is installed in a printer. By the effect of the phase shift element, the intensity of side lobes (several rings of light accompanying the main beam) is prevented from exceeding a threshold value even when optical surfaces of an imaging optical system of the scanning optical system have certain microscopic undulations, by which black stripes occurring in halftone printing can be eliminated.