Abstract: Disclosed is a scanning optical system for emitting a scanning beam onto a surface to be scanned. The scanning optical system is provided with a laser source that emits a laser beam, a deflector that deflects the laser beam emitted by the laser source towards an f.theta. lens the laser beam passed through the f.theta. lens scans on the surface to be scanned the f.theta. lens includes at least one lens which is formed to cancel an uneven intensity distribution characteristic of the scanning optical system within an area where the laser beam scans on the surface to be scanned.

Abstract: An optical scanning lens is for use in an optical scanning device in which a light beam forming a line image elongated in a direction corresponding to a main-scanning direction is deflected at a constant angular velocity by a deflector having a reflecting surface in a vicinity of a position of the line image, and in which a deflected beam is focused by the optical scanning lens to form a beam spot on a surface to be scanned so that a constant velocity optical scanning of the surface to be scanned is effected, the optical scanning lens having a single-lens construction and being constructed such that at least one of lens surfaces has an asymmetrical configuration with respect to an optical axis within a plane of deflection, the asymmetrical configuration with respect to the optical axis being designed so that a field curvature is properly corrected and a proper constant-velocity characteristic is obtained over an entire effective optical scanning area, and the plane of deflection being defined as a plane inclu

Abstract: A color printer for imaging on an image plane includes: (a) a plurality of light sources, each of the light sources being adapted to provide a spatially coherent, composite beam of light, each of the composite beams including a plurality of spectral components; (b) a single beam shaping optics accepting the composite beams, the beam shaping optics having optical elements adapted to shape said composite beams by a different amount in a scan direction and a cross scan direction, so as to form for each of the composite beams (i) a first beam waist in the cross scan direction of the composite beam and (ii) a second waist in the scan section of the composite beam, the first and second beam waists being spaced from one another; (c) a deflector adapted to move said plurality of composite beams across the image plane, the deflector being located closer to the first beam waists than to the second beam waists; and (d) scan optics located between the deflector and the image plane, the scan optics being adapted to (i) ge

Abstract: A printer system for producing color prints includes: (a) three light sources, each generating a light beam of different wavelengths; (b) three modulators, each of the modulators modulating intensity of each of the light beams by image data, to provide three modulated light beams; (c) a beam combiner combining the three modulated light beams into a single light beam; (d) a single set of beam shaping optics shaping this single light beam into a shaped light beam having different vergences and waist locations in the page and line directions, the vergences and the waist locations being substantially the same in each of the three wavelengths; (e) a light deflector deflecting the shaped light beam to provide a deflected beam, and performing a scanning function; (f) an f-.theta. lens focusing the deflected light beam onto an associated image surface.

Abstract: A collimator lens having five lens elements of negative, negative, positive, positive, and negative refractive power, in order from a collimated luminous flux side of the collimator lens, and designed to have a large back focus, to thereby prevent heat from the light source from causing aberrations in the collimator lens. The collimator lens includes a negative first lens element L.sub.1 of a meniscus shape with its concave surface on the collimated luminous flux side, a positive fourth lens element L.sub.4 with a convex surface on the collimated luminous flux side, and a negative fifth lens element L.sub.5 with a concave surface on the collimated luminous flux side. In addition, a diaphragm stop is arranged on the collimated luminous flux side of the first lens element, and certain conditions are satisfied to reduce aberrations and provide a large back focus.

Abstract: An optical system for light scanning devices in which a beam of light travels from an origin to an object along a light path and has along that path a scan direction and a cross-scan direction. The optical system includes a light source at the origin of the light path, a polygonal reflector located along the light path and having adjacent peripheral mirror surfaces rotatable in the scan direction, and a pre-scan optical sub-system located along the light path between the light source and the polygonal reflector. The pre-scan optical sub-system includes, in order of light travel from the light source, a collimating lens and a pre-scan lens having a convex cylindrical lens entrance surface aligned in the scan direction for converging the light beam in the cross-scan direction, and a convex lens exit surface for converging the light beam in the scan direction. An aperture stop may be provided between the collimating lens and the pre-scan lens to further truncate or reduce the diameter of the collimated beam.

Abstract: A scanning optical apparatus includes a light source device, a first optical element for converting a beam emitted from the light source device to a converging light beam, a deflecting element for deflecting the beam emitted from the light source device, a second optical element for focusing the beam emerging from the first optical element in a linear shape longitudinal in a main scanning direction on a deflective face of the deflecting element, and a third optical element for focusing the beam deflected by the deflecting element in a spot shape on a scanned surface.

Abstract: A projection lens system that is used to transfer a pattern from a reticle onto a wafer, incorporates a projection optical system that is capable of maintaining the same, or increased performance, as the current projection lens systems, and that achieves excellent aberration correction, has a numerical aperture of at least 0.6, an exposure field area of at least 18.7.times.18.7 mm or at least 26.45 mm diameter at the wafer plane, and has a total lens thickness to length ratio less than 0.64 and uses 5 or less aspherical lens surfaces.

Abstract: An F-theta scan lens for a dual beam, dual wavelength raster output scanning system (ROS) has four lens elements with the third and fourth lenses forming a doublet having a negative refractive power. This four-element F-theta scan lens corrects for axial chromatic aberration and lateral chromatic aberration for both wavelengths and provides scan linearity.

Abstract: A scanning optical system which includes a light source for emitting a beam of light, a light deflector for deflecting the beam of light in a main scanning direction, and a scanning lens which receives a beam of light deflected by the light deflector for focusing the deflected beam of light onto a scanning surface. The scanning lens includes a lens having a refractive index distribution in either the main or the sub-scanning direction.

Abstract: To provide an optical scanner for typical use with laser beam printers that is capable of effective correction of aberrational characteristics and which also produces a constant beam spot size, a semiconductor laser array 1 having a plurality of light-emitting portions issues a plurality of beams, which are reflected and deflected by reflecting surfaces of rotating polygonal mirror 5 and pass through imaging lens 6 to form a plurality of beam spots on the surface to be scanned 7. Both the entrance and exit surfaces of imaging lens 6 are such that the curvatures in the sub- and main scanning directions are independent of each other, with the curvature in the sub-scanning direction varying continuously in the main scanning direction over the effective area of imaging lens 6.

Abstract: A projection lens for use with LCD panels is provided. The lens has two aspherical meniscus elements which are concave to each other and are located in the vicinity of the lens' aperture stop and a color-correcting doublet which provides most of the positive optical power of the lens. The lens can also include an aspherical corrector lens element of weak optical power which is located on the side of the two meniscus elements opposite to the color correcting doublet.

Abstract: An achromatic, telecentric f-theta scan lens optical system for a raster output scanner has a positive crown glass lens element, a negative flint lens element and a concave mirror. The refractive indices of the positive crown glass lens element and the negative flint lens element are sufficiently different to achieve achromatization of a light beam by the two lens elements. The positive crown glass lens element, the negative flint lens element and the concave mirror form a telecentric optical system.

Abstract: An f-.theta. lens is disclosed which is particularly suitable for use with a color laser printer in which beams of different wavelengths are combined into a single light beam. The combined light beam is scanned by a rotating polygon onto a receiving medium. The f-.theta. is adapted to operate with 1.) beam shaping optics for shaping the beam in a scan direction prior to the polygon, and 2.) a cylindrical element located behind the f-.theta. lens, to image the light beam in a cross-scan direction onto the receiving medium. The f-.theta. lens includes a plurality of lens components. The lens components cooperate to(a) focus a received combination beam of three different wavelengths onto an image surface, the received combination beam having different vergences and different waist locations in the page and line directions, the vergences and the waist locations being substantially the same in each of the three wavelengths; and(b) compensate for chromatic aberration. This compensation renders the f-.theta.

Abstract: A scanning optical apparatus includes a light source, a first optical system for converting a light beam emitted from the light source into a focused beam, a deflector for deflecting the light beam emerging from the first optical system, and a second optical system for imaging the light beam deflected by the deflector into a spot image on a surface to be scanned. The second optical system is constituted by a single lens whose two lens surfaces have aspherical shapes in a main scanning plane, andthe following conditions are satisfied:0<R1<.vertline.R2.vertline.R2<0(R1.sup.2 -Ymax.sup.2).sup.1/2 -R1<S1<0.vertline.R2.vertline.-(R2.sup.2 -Ymax.sup.2).sup.1/2 -d<S2<00.2.ltoreq.1-Sk/ft.ltoreq.0.

Abstract: A scanning optical system is provided with a scanning lens which images a luminous flux deflected by a deflector at a constant angular speed on a surface to be scanned so that the luminous flux scans the surface to be scanned substantially at a constant speed. At the cross section in the main scanning direction, the luminous flux incident on the scanning lens is a convergent light beam, and the scanning lens includes from the deflector side a first lens of a positive paraxial refractive power and a second lens of a negative paraxial refractive power.

Abstract: An optical scanning lens is provided with a lens configuration for focusing and correction of field curvature and scanning speed of a deflected laser beam. The lens configuration includes a meniscus lens and a positive meniscus lens sequentially aligned and sharing an optical axis with the optical scanning lens. Specific parameters are provided for each lens in order to satisfy the relationship:-0.25<f.sub.2 /f.sub.1 <0.11,between respective focal lengths of the lenses, and the surfaces of the meniscus lens have radii of curvature satisfying the relationship:0.8<r.sub.1 /r.sub.2 <1.25.The above relationships provide for correction of scanning speed and field curvature in a main scanning direction. Specific lens surfaces are identified and provided with an aspheric surface which provides additional field curvature correction in the main scanning direction.

Abstract: An optical condenser system for a light scanning apparatus includes a first lens which is a single lens formed of plastic and a second lens which is a plano-convex lens formed of glass and convex toward the scanning surface. The first lens is concave toward a deflector of the light scanning apparatus and each side of the first lens is an aspheric surface defined by the following formula (6). The first and second lens satisfying the following formulae (1) to (5)0.1f.ltoreq.d.sub.0 .ltoreq.0.3f (1)0.02f.ltoreq.d.sub.2 .ltoreq.0.2f (2)-1.0.times.10.sup.2 /f.sup.3 .ltoreq.a.sub.1 .ltoreq.-1.0/f.sup.3( 3)5.0.times.10/f.sup.5 .ltoreq.a.sub.2 .ltoreq.5.0.times.10.sup.3 /f.sup.5( 4 )-0.3/f.ltoreq.1/f.sub.1 .ltoreq.0.3f (5)z=ch.sup.2 /?1+{1-(1+K)c.sup.2 h.sup.2}.sup.1/2 !+a.sub.1 h.sup.4 +a.sub.2 h.sup.6 +a.sub.3 h.sup.8 +a.sub.4 h.sup.10 ( 6)wherein f represents the focal length (mm) of the whole system, d.sub.

Abstract: Single convex lens element has a positive power in both the main and sub-scanning directions on the surface which is the closer to the surface to be scanned and which is anamorphic such that any section taken through a plane that is parallel to the central optical axis and which is normal to the main scanning direction provides a generally constant surface geometry along the length of that surface. This lens ensures not only the production of a good image plane and satisfactory f.theta. characteristics in the main scanning direction but also the effective correction of the curvature of the field in the sub-scanning direction.

Abstract: A scanning (f.theta.) lens includes first, second, third, and fourth lenses, respectively having negative, positive, positive, and negative power in at least the main scanning directions. The lenses are arranged in order from a polygon mirror to a drawing surface. The Abbe number of the fourth lens is less than 40. In a further refinement, the Abbe number of the fourth lens subtracted from half the difference between the Abbe numbers of the second and third lenses is greater than 20. In another refinement, the scanned surface side surface of the first lens element is a cylindrical surface having negative power only in the auxiliary scanning direction, and the scanned surface side surface of one of the second or third lens elements is a toric surface having greater positive power in the auxiliary scanning direction than in the main scanning direction.

Abstract: An optical system for scanning a light beam across an object where the light beam is double reflected by the reflection surfaces of a rotating polygonal mirror. Beam expander optics are included in the light path for the light beam following the first reflection by the polygonal mirror to magnify the beam diameter to fill the length of the reflective surface of the polygonal mirror at the second reflection. The beam expander optics further include lenses for demagnifying scan angle in the light beam following the first reflection. The lenses of the beam expander optics are formed with a Petzval curvature (third order Seidel aberration) to correct for the distortion induced in the optics image plane by the longitudinal shift in the entrance pupil position at the first reflection as the polygonal mirror rotates.

Abstract: A scanning lens converges light deflected by a deflector onto a surface to be scanned, comprises a first lens having a negative power in both a main scanning direction and in an auxiliary scanning direction, a second lens having a positive power in both the main scanning direction and in the auxiliary scanning direction, a third lens having a positive power in both the main scanning direction and in the auxiliary scanning direction, and a fourth lens provided with a cylindrical surface having a negative power in the auxiliary scanning direction. The first, second, third and fourth lenses are arranged in this order from the deflector. The first, second and third lenses are formed so that curvature of field in the auxiliary scanning direction is reduced. A bow of an abaxial scanning line, which cannot be corrected by the first, second and third lenses, can be corrected by the cylindrical surface of the fourth lens.

Abstract: A scanning apparatus has a luminous flux deflector and a single f.theta. lens. The deflector deflects a convergent luminous flux on a scanned surface at a uniform angular velocity. The f.theta. lens is arranged between the deflector and the scanned surface. The f.theta. lens is bi-convex in a main scanning direction and is made of a material having a refractive index of at most 1.6. One surface of the f.theta. lens in a main scanning direction is so curved that a radius of curvature in the main scanning direction decreases as an angle of view in the main scanning direction increases.

Abstract: Improved optical scanner comprises semiconductor laser 10, aperture 12, collimator 14, cylindrical lens 16, polygonal mirror 18 and single-element f.theta. lens 22 which is formed of an amorphous polyolefin as a plastic material. Surface S1 of f.theta. lens 22 which is on the side adjacent polygonal mirror 18 is aspheric and asymmetrical with respect to an axis of rotation, and opposite surface S2 on the side adjacent photoreceptor drum 26 is also aspheric but symmetrical with respect to an axis of rotation. Lens surface S1 is an anamorphic aspheric surface which is convex toward polygonal mirror 18 in the deflecting plane due to the positivity of the paraaxial radius of curvature R1M but which is concave toward the polygonal mirror 18 in the plane orthogonal to the deflecting plane due to the negativity of the paraaxial radius of curvature R1S.

Abstract: An f.theta. lens includes first and second lens groups arranged in this order from the entrance pupil side. The first lens group consists of a first lens having a negative or positive refracting power. The second lens group consists of a second lens having a positive refracting power and a third lens having a negative refracting power with the second and third lenses being cemented together. The second lens group has a positive refracting power as a whole. The following formulae (1) to (4) are satisfied.12.ltoreq..nu..sub.d2 -.nu..sub.d3 (1)-0.035.ltoreq..SIGMA.(.phi..sub.i /.nu..sub.di).ltoreq.0.005 (2)0.7.ltoreq..phi..sub.23 .ltoreq.2.0 (3)0.03.ltoreq.d.sub.12 .ltoreq.0.20 (4)wherein .phi..sub.i represents the power of i-th lens as numbered from the entrance pupil side standardized on the basis of the power of the whole system, .phi..sub.23 represents the power of the second lens group standardized on the basis of the power of the whole system, .nu..sub.

Abstract: An f.theta. scanning lens arrangement, arranged from a polygonal mirror side to an imaging surface side, including a first, second, third, and fourth lens with having negative, positive, positive, and negative power, respectively, in the main scanning and subscanning directions is provided. The ratio of the focal length in the main scanning direction of the fourth lens versus the focal length in the main scanning direction of the entire f.theta. lens is selected to simultaneously minimize astigmatism, field curvature, and linearity error. Further, the ratio of the focal length in a subscanning direction of the first lens versus the focal length in the subscanning direction of the second lens is selected to minimize curving of scanning lines displaced from the optical axis.

Abstract: In a condenser optical system for a light scanning system, a single lens focuses a light beam deflected by a reflecting surface of a deflector onto a surface to be scanned and causes the deflected light to scan the surface in a main scanning direction at a constant speed. A cylindrical mirror which has a refracting power only in a sub-scanning direction normal to the main scanning direction compensates for surface tilt of the reflecting surface. At least one surface of the single lens is toric to compensate for the surface tilt associated with the cylindrical mirror and the toric surface is aspheric in a main-scanning cross-section.

Abstract: In a scanning image forming lens used in an optical scanner, a light beam from a laser light source is coupled and deflected at an equal angular velocity by an optical deflector and is converged as a light spot on a scanned face by the scanning image forming lens to optically scan the scanned face at an equal speed. The scanning image forming lens is constructed by first and second plastic lenses such that the first lens is constructed by a positive meniscus lens having a concave face directed onto an optical deflector side. The second lens is arranged near a scanned face side of the first lens. At least one face of each of the first and second lenses is constructed by an aspherical surface. .vertline..theta..sub.1 /.theta..sub.2 .vertline. has a local minimum near an optical axis of the scanning image forming lens and is increased from the optical axis toward a peripheral portion of the scanning image forming lens when .theta..sub.

Abstract: A novel optical scanning system which is cheap to manufacture, which exhibits an excellent f.sub..theta. characteristic and which satisfactorily corrects curvature of field in a sub scanning parallel direction. The optical scanning system is formed by two or more lenses. One of the two or more lenses is a corrector lens which corrects curvature of field in the sub scanning parallel direction. The corrector lens is made of plastic so as to have a substantive power only in the sub scanning parallel direction. The corrector lens is smoothly curved along its longitudinal direction into a shape which corrects curvature of field in the sub scanning parallel direction. The cross-sectional configuration of the corrector lens taken in a plane which is parallel to a central optical axis and perpendicular to a main scanning parallel direction is approximately constant along the longitudinal direction of the corrector lens.

Abstract: A scanning optical system including a light deflector rotating about a rotational axis perpendicular to a main scanning direction, a laser beam emitter for emitting a laser beam which scans a scanning surface along the main scanning direction and for making the laser beam incident upon the light deflector with a first angle with respect to a sub-scanning direction perpendicular to the main scanning direction, a curved mirror having a curvature at least along the main scanning direction for reflecting a laser beam deflected by the light deflector with a second angle with respect to an incident laser beam upon the curved mirror, and an anamorphic lens disposed between the curved mirror and the scanning surface. The anamorphic lens has a first surface having a first aspherical surface along the main scanning direction, and a second surface having a second aspherical surface which is not rotationally symmetrical about an optical axis of the anamorphic lens.

Abstract: This invention discloses an optical scanning apparatus which gives an F-.theta. function by means of an axis-symmetric aspherical lens serving as a scanning lens and facilitates the manufacture, assembly and adjustment of the lens by providing a cylindrical lens between a rotating polygon mirror and the axis-symmetric aspherical lens. According to this invention, two lenses which may be injection moulded and use plastic material form an optical scanning system. The cylindrical lens of these two lenses is located between the rotating polygon mirror and the scanning lens for image-forming light in the subscanning direction, the scanning lens of these two lenses is located between the cylindrical lens and the image formation plane for image-forming light in the mainscanning direction. Also, magnification of the mainscanning direction and that of the subscanning direction are independent.

Abstract: A scanner configured to provide a two-dimensional scan of a radiation beam moving along the path, including two deflectors and a scan lens located downstream in the path of the beam from the deflectors and separated from the farthest deflector by air equivalent distance at least equal to the focal length of the scan lens.

Abstract: An f.theta. lens system employing two f.theta. lenses in a laser scanning unit. According to the f.theta. lens system, a cheap plastic can be used for an f.theta. lens by lowering the refractive index of one of two f.theta. lenses and forming a toric face on one of total four refractive faces. Incident and emergent faces in the cross scan direction of a first f.theta. lens closer to a rotary polygon mirror has the curvature of .infin., and an incident face in the main scan direction of a second f.theta. lens closer to a photoconductive drum also has the curvature of .infin.. Thus, only an emergent face of the second f.theta. lens has a toric face.

Abstract: An optical scanner including a semiconductor laser device, aperture, collimator, cylindrical lens, polygonal mirror and one f.theta. lens element molded from plastics. The first surface of the f.theta. lens in a deflecting plane (or the plane formed by the principal rays of light as deflected by the polygonal mirror) is aspheric whereas the second lens surface is toric. When taken in the deflecting plane, the first lens surface has a positive value of the near-axis radius of curvature and, hence, it is convex toward the polygonal mirror. Taken in a plane crossing the deflecting plane at right angles, the first lens surface forms an arc of a circle having a negative value of the radius of curvature and, hence, it is concave toward the polygonal mirror. When taken in the deflecting plane, the second lens surface forms an arc of a circle having a negative value of the radius of curvature and, hence, it is convex toward the scanning surface.

Abstract: A high resolution with at the same time high testing speed is required of scanning objectives for the linewise or pointwise three-dimensional scanning of object surfaces. In order to be able to image as many image points as possible with high resolution, the scanning objective must exhibit a correspondingly large numerical aperture with, at the same time, a large image field. For this purpose, it is constructed of three lens groups (1; 2; 3). The first and second lens groups (1; 2) effect both a scan angle reduction and a pupil enlargement. The entrance pupil (61) is imaged into the entrance pupil (63) of the third lens group (3). The third lens group (3) has a large numerical aperture of, for example, 0.6. Furthermore, the real intermediate image (5) is imaged by the second lens group (2) with positive refractive power and greater focal length (f) than the first lens group (1), at infinity. With a beam diameter (D) at the entrance of the scanning objective of 7.5 mm, a scan angle (.theta.) of +/-16.degree.

Abstract: An optical scanner for use in laser beam printers and the like which is particularly satisfactory in imaging characteristics. A light beam from a semiconductor laser passes through a collimator lens, an aperture diaphragm and a cylindrical lens. The beam is then deflected by a rotating lens mirror and subjected to the focusing action of an imaging lens so that it is focused to form a beam spot, which scans over a scan surface as the beam is deflected. The imaging lens has aspheric surfaces in the main-scanning cross section and is designed so that the rate of change in its curvature and other relevant parameters satisfy a predetermined equation so as to lie within a predetermined range.

Abstract: An anamorphic single lens has its radii in respective directions determined by the transfer efficiency of beams and imaging positions in respective directions, as required by the overall optical scanner. The anamorphic single lens satisfies the following formulae: ##EQU1## where fm is the focal length of the lens in the direction of beams diverged at a larger angle, TH is the thickness, S is the distance from a light source side principal point position (6) to the light source (5) in the direction of the beams diverged at the larger angle, and S' is the distance from a light source side principal point position (8) to the light source in the direction of beams diverged at a smaller angle.

Abstract: A laser beam scanner is composed of an optical source, a beam deflector for deflecting the beam emitted from the optical source and a sensitive drum for performing printing and photosensitive processes from the beam after its deflection by the beam deflector. Also, the laser beam scanner comprises an f-.theta. lens between the beam deflector and sensitive drum for increasing resolution. The f-.theta. lens is composed of a first lens for correcting aberrations and a second lens for correcting the deflected beam passed through the first lens. The f-.theta. lens is made of plastic whose cost is lower than that of glass and can be easily manufactured since the beam emitting surface of the f-.theta. lens is spherical.

Abstract: A scanning apparatus has a luminous flux deflector and a single f.theta. lens. The deflector deflects a convergent luminous flux on a scanned surface at a uniform angular velocity. The f.theta. lens is arranged between the deflector and the scanned surface. The f.theta. lens is bi-convex in a main scanning direction and is made of a material having a refractive index of at most 1.6. One surface of the f.theta. lens in a main scanning direction is so curved that a radius of curvature in the main scanning direction decreases as an angle of view in the main scanning direction increases.

Abstract: A field curvature corrector is provided which has a positive power and a positive exact field curvature (EFC) value for at least one principal ray, where the EFC value is given by:EFC=-.SIGMA.(n'-n)c/nn'the summation being taken over the surfaces of the corrector, and for each of the surfaces, n is the index of refraction on the object side of the surface, n' is the index of refraction on the image side of the surface, and c is the curvature of the surface at the intersection of the surface with the principal ray, c being positive if the center of curvature is on the image side of the surface. By means of the corrector, the field curvature of a positive lens system can be corrected without the use of negative lens elements.

Abstract: An optical scanning system is provided which includes a light source, a scanning deflector which deflects a bundle of rays emitted from the light source, and a scanning lens system which converges the deflected bundle of rays onto an image surface to form an image. The scanning lens system has at least two lenses, wherein the lens closest to the image surface is a meniscus lens with a surface which is convex in the main scanning direction facing the image surface. A surface of the meniscus lens nearest to the scanning deflector is a deformed toric surface which is convex in a sub scanning direction facing the scanning deflector. The sub scanning direction is normal to the main scanning direction. The convexed toric surface has a radius of curvature which is determined independently of a radius of curvature in the main scanning direction.

Abstract: An optical scanning system is provided which includes a light source, a scanning deflector which deflects a bundle of rays emitted from the light source, and a scanning lens group which converges the deflected bundle of rays onto an image surface to form an image. The scanning lens group includes at least one glass lens and at least two plastic lenses, and the at least one glass lens provides substantially all the power of the scanning lens group.

Abstract: An airspaced, diffraction limited, seven element telecentric f-theta lens having a first meniscus lens concave to the incident side; a first bi-concave lens; a second meniscus lens convex to the incident side; a third meniscus lens concave to the incident side; a pair of bi-convex lenses; and a second bi-concave lens is disclosed. The second, third and fourth as well as the sixth and seventh lens elements are edge contact spaced.

Abstract: Both of the first surface and the second surface of the one-piece f.THETA.-DEC scanning lens of the present invention have to be in accordance with the following equation: ##EQU1## and the following criterion has to be satisfied: (1) 0.27.ltoreq.fx/fy.ltoreq.0.35(2) .vertline. R.sub.1 y .vertline. > .vertline. R.sub.2 y .vertline.(3) 0.3<R.sub.2 x/R.sub.2 y<0.6, R.sub.1 x/R.sub.1 y.ltoreq.0Therefore, the one-piece f.THETA.-DEC scanning lens of the present invention is capable of replacing a convention two-element f.THETA. lens group so as to compensate the Wobble effect, scan linearly, and greatly decrease the setup volume of the scanner at the same time.

Abstract: An apparatus for recording an image with a plurality of laser beams on a recording surface comprises a plurality of laser source units each generating a laser beam and a first lens for directing the laser beam from each one of the plurality of laser source units to the recording surface. In the apparatus, the laser source units are each disposed on a holding member in such a manner that the principal ray of the laser beam therefrom passes through a front focal point of the first lens. Thus, the apparatus is advantageous in that it is not necessary to employ an enlarged lens despite increase in the number of the laser source units, or the channel numbers.

Abstract: An achromatic-type scanning optical arrangement includes a laser source, a first optical system for converging a beam of light emanating from the laser source, a deflecting device for deflecting the beam of light converged by the first optical system and a second optical system for focusing the beam of light deflected by the deflecting device onto a predetermined position. The entire optical system including the first optical system and the second optical system is corrected for chromatic aberration, as a whole, to eliminate the adverse influence of wavelength variations in the laser source upon variations in the focus position of the aforesaid beam of light.

Abstract: An optical scanning apparatus for effecting the scanning with plural light beams, without aberrations among the obtained scanning lines and without curvature in the scanning lines. For this purpose plural light beams emitted from plural light sources are deflected by a single deflector, composed for example of a rotary polygon mirror, and guided to respective scanned planes through a scanning condenser lens system, having the f-.theta. characteristics in the scanning direction and also having plural optical axes in the sub scanning direction.

Abstract: A scanner system includes a light source for producing a light beam and a multifaceted polygon for scanning the light beam in a scan plane along a scan line a predetermined distance from the polygon, such as at the surface of a photoreceptor or a document to be read. The system also includes a post-facet lens system that includes first and second elements configured to compensate for field curvature and wobble without compensating for scanner non-linearity. Preferably, the first element and second elements are so disposed that the light beam passes first through the first element and then through the second element. In addition, the first element preferably includes first and second surfaces such that the light beam passes from the first surface to the second surface, the first surface being spherical and the second surface being cylindrical with curvature in the scan plane and essential no curvature in the cross-scan plane.

Abstract: In an optical scanner, a light beam emitted from a semiconductor laser is changed to a parallel light beam by a collimator lens and the parallel light beam is formed by a first optical system as a linear image extending in a main scan-corresponding direction. The image-formed parallel light beam is deflected at an equal angular velocity by a rotary polygon mirror having a deflection reflecting face in the vicinity of the linear image. The deflected light beam is formed as a light spot on a scanned face by a second optical system to perform an optical scanning operation. An f.theta. lens in the optical scanner is used as the second optical system. The f.theta. lens has an f.theta. function in the main scan-corresponding direction and a function for setting the scanned face and a deflecting start point on the deflection reflecting face in an approximately conjugate relation in geometrical optics in a cross scan-corresponding direction. The f.theta.

Abstract: A lens system is provided which includes two lens units. The first lens unit includes two meniscus lenses whose concave surfaces face each other and the second lens unit has a positive power. The system can be configured to have a wide field of view and/or to be telecentric. In its basic form, a well-corrected lens having a relatively large aperture and field of view is achieved through the use of only three lens elements.