Abstract: A scanning optical system for preventing ghosting is provided wherein a laser beam emitted by a laser light source is first brought to an image in an auxiliary scanning plane, and reflected by a slit mirror provided in a prism block. The laser beam is incident on the scanning deflector along the optical axis of the scanning lens, and a screen is provided for obstructing ghosting in the vicinity of the scanning surface. Further, at least one side of the prism block on which the light is incident from which the light emerges is curved, or one side of the prism block is treated to prevent reflection. Further, the screen is disposed between the laser light source and the slit mirror so as to obstruct the part of the light beam incident on the mirror which is reflected by the mirror after being reflected by the scanning deflector.

Abstract: A laser tracking device for the warning of vehicle weaving and steering assistance of vehicles, includes a laser generation apparatus for generating and transmitting a laser beam. A mirror is provided for sweeping the laser beam across a roadway surface. The mirror also receives a reflection of the laser beam back from a roadway marker located on the roadway surface and directs it to a receiver. A master clock is coupled to the mirror for generating a first timing signal when the laser beam starts to sweep across the roadway surface. The receiver generates a second timing signal when the reflected laser beam is incident on it. A processor is coupled to the receiver and the master clock. The processor compares the first timing signal with the second timing signal. The processor uses the results of that comparison to calculate the distance between the vehicle and the roadway marker.

Abstract: In a variable density scanning apparatus, a variable focal distance device is provided in a scanning optical system. This variable focal distance device is formed of a light waveguide having a plurality of electrodes provided of which the lengths along the direction of incident laser beam are decreased or increased with the increase of the distance from the central electrode. The voltage to be applied between the electrodes is controlled in accordance with a desired dot pattern so as to change the refractive index of the light waveguide through which the laser beam is passed, thereby effectively changing the focal distance so that the diameter of the scanning laser beam spot can be changed in one dimension.

Abstract: In a bar code laser scanning system operable in a continuous scan mode and a sleep mode, an object sensing circuit for automatically switching said laser scanning system from the sleep mode to the scan mode is provided to help extend the operational lifetimes of the system components such as the laser diode and the scanning motors. When in the sleep mode, pulsed light is received and processed to generate a steady state voltage signal. Derived from the steady state voltage signal is a positive threshold voltage signal and a negative threshold voltage signal each having a magnitude respectively greater than and less than that of the steady state voltage level. The steady state, positive threshold and negative threshold voltage signals are input to a comparator means which detects when an object is placed in the scanning field of the laser scanning system.

Abstract: A multichannel imaging spectrometer for airborne geological, geophysical and environmental surveys in a moving vehicle. An optical scanner employs a rotating polygon allowing reduced scan optics with increased data acquisition efficiency. Multiple spectrometers integrally registered allow channelization of the received signal to optimize noise performance in the range from ultraviolet through infrared. Output data is in a form for recording and real time display. A staring mode configuration provides enhanced sensitivity by using a two-dimensional detector array and adjustable mirror orientation. A scanning mode embodiment employs a two-dimensional detector array with time delay integration and three-dimensional storage of temporal spatial data and spectral wavelength and intensity. Thus, all channels are acquired simultaneously, resulting in perfect band-to-band registration with continuous spectral curves over the field of view.

Abstract: A raster scanning system is disclosed which utilizes a focus error correction system for correcting a focus error both in the fast-scan plane and in the cross-scan plane without affecting the scan characteristics of the post polygon optics. The focus error correction system comprises at least two axially adjustable lenses. One of the lenses is spherical and the other is cylindrical in the fast scan plane. The spherical lens has to be adjusted first to correct the focus error in the cross-scan plane. Next, the cylindrical lens should be adjusted to correct the focus error in the fast-scan plane.

Abstract: An image scanning and recording method for compensating for a pyramidal error of a mirror surface of a rotating body having at least two reflective mirror surfaces by fine-adjusting an angle of a light beam incident on the rotating body. A scanning lens is put in such a manner that an optical axis of the scanning lens is orthogonal to a rotating axis of the rotating body. An angle made of the incident light beam and a main scanning plate is controlled so that equations (I) and (II) are selectively fulfilled, the main scanning plane being orthogonal to the rotating axis and including the optical axis:tan .alpha.=tan2.delta..multidot.cos(a-b) (I).alpha.=2.delta..multidot.cos(a-b) (II)where a: a rotating angle of a normal line standing on each mirror surface with respect to the optical axis of the scanning lens, b: an angle made of the incident beam and the optical axis of the scanning lens on the main scanning plane, and .delta.: the pyramidal error of each mirror surface with respect to the rotating axis.

Abstract: A raster scanning system is disclosed which utilizes a rotating prism for facet tracking. The rotating prism has a plurality of facets and each facet is parallel to an opposite facet. A light beam enters through one facet of the rotating prism and exits the corresponding parallel facet. The light beam passing through the rotating prism deflects and since the the prism rotates the light beam also shifts. The prism shifts the light beam in such a manner to keep the beam at the center of a mirror facet of a rotating polygon mirror.

Abstract: A system is described for providing positional information regarding a media sheet in an image forming apparatus. The system includes a laser for providing a beam of collimated light and a mechanism for moving a media sheet along an imprinting path. Beam sensors are placed in the imprinting path, and positioned so as to be partially shaded by a media sheet when it is moved along the imprinting path. A scanning system moves the light beam across the media sheet and past its edges to cause the beam to fall on the beam sensors, when the media sheet is partially shadowing the beam sensors. A processor is responsive to outputs from the beam sensors to determine positional information regarding the media sheet. Positional information is derived by determining the time during which the scanned beam is incident on a sensor.

Abstract: The present invention concerns device for the acquisition of the angular position of mobile means of the type including a luminous source emitting an incident beam in a known direction and a reflecting surface attached to the mobile means. The device also includes an array of elementary charge coupled sensors positioned so as to be at least partly scanned by the reflected beam. The device includes in addition optical means for limiting the width of the incident beam. The said array is connected to an electronic circuit producing a digital signal varying according to the position and/or the number of elementary sensors illuminated by the reflected beam.

Abstract: A polygonal scanning mirror for an optical recorder is magnetically suspended and rotated about a scanning axis. To control position of the scanning mirror, a curved surface mirror is fixed with respect to, and rotates with, the scanning mirror for receiving a radiation beam and reflecting it onto a detector array. The reflected radiation beam is preferably focused by an astigmatic imaging system. Output signals from the detector array are used to control electromagnets of the suspension system.

Abstract: Beam position sensors detect deviations of a light beam from target positions defined at both sides of a recording drum. Predicted total deviations of light beam from the target positions are calculated as a function of beam position signals detected by the beam position sensors. A piezoelectric element of a sub-deflector is actuated in response to the predicted total deviations. The light beam deflected by a main deflector scans the target positions on a recording medium.

Abstract: An optical deflector is employed in an optical unit incorporated in a laser beam printer. The optical deflector reflects a laser beam, which is generated by a laser diode toward a photosensitive body and is made to have a cross section of desirable size by a group of conversion lenses. The optical deflector is provided with reflecting surfaces whose cross sections are convex in a main scanning direction. The number of reflecting surfaces is defined by 4.times.m (m: a natural number), and therefore the optical deflector has four or eight reflecting surfaces, for instance. Since the number of reflecting surfaces is defined by 4.times.m, reflecting surfaces can be positioned easily and reliably with reference to the center of the shaft.

Abstract: The method and apparatus for using a light beam to scan media, particularly radiographic film media, for digitization wherein the scanning beam and the media transport path are optimized to minimize interference of the incident directly transmitted scanning beam with light internally reflected back by the light exit surface of the media, which gives rise to significant modulation of the transmitted intensity and forms contour or fringe patterns which follow small variations in the media thickness. An optical light beam shaping system is employed to generate a generally elliptical or elongated cross-section light beam having a major and minor axis. A scanner deflects the light beam through a predetermined, flat scanning angle in a scan direction forming a scanning line on the incident surface of the film media. The film media is transported past the scanning light beam such that successive lines of the media are scanned.

Abstract: A confocal microscope (10) includes a scanner assembly (38) in which the x-axis deflector assembly includes two resonant scanners (50 and 52) that oscillate about parallel axes at different frequencies, one of which is a harmonic of the other. As a consequence, the x-axis scan can be nearly linear even though it is provided resonantly and thus benefits from the high-speed capabilities of resonant systems. A galvanometer (64) pivots the housing of one of the resonant scanners (50) about its axis so as to provide x-axis panning.

Abstract: An optical scanning method is described in which a device essentially comprises a rotational optical system S and a working plane W fed in a predetermined direction. The optical system forms the image of a stationary point A at point B on the working plane W. The image point is scanned along a circular are by rotating the optical system around the rotational axis. In a preferred device, point A lies approximately on the rotational axis and point B lies off the rotational axis. And the circular arc generated by the scanning of point B is in the working plane approximately perpendicular to the rotational axis. A 2-dimensional scanning is completed by the rotation of the optical system around the rotational axis and the translation of the working plane in a predetermined direction, which is synchronized with the rotation of the optical system. When the radiation beam E propagates from point A to B, the device is for information writing in (e.g. lithography) and the working plane is a recording medium.

Abstract: An operation control system for a scanning galvanometer associated with an arc sensor (20) of a welding robot for sensing a weld line, and having a swing mirror (23) integral therewith for a laser beam scanning. A memory (43) stores waveform data of a galvanometer drive command current obtained by synthesizing a constant-speed command current and an acceleration/deceleration command current, and an address circuit (42) causes the waveform data to be output from the memory (43) at predetermined intervals. A D/A converter (44) converts the output of the memory (43) to an analog value, and a scanner drive circuit (45) drives the galvanometer (22), which swings the swing mirror (23) to detect the weld line.

Abstract: A method of slow, or process, scan direction spot registration or position control in an optical output device, such as a raster output scanner (ROS), may be facilitated by interposing in the image path an electro-optic element whose angular dispersion varies for a given wavelength as a function of the electrical bias applied to it. By orienting the electro-optic element such that dispersion control is perpendicular to the fast or line scan direction of the ROS, varying the electrical bias applied to it varies the dispersion in the slow scan direction. The electro-optic element may be, for example, a prism of AlGaAs. Bias applied to the electro-optic element may be in response to the output of a means for detecting and quantifying such positional errors and/or in response to predetermined correction information output from a processor controlled memory unit or the like. Spot position for single or multiple beam optical output device may be achieved.

Abstract: In an optical output device wherein a beam of light is generated and focused to a spot upon an image plane, such as a photoreceptor in a xerographic printing apparatus, an apparatus for controlling the position of the spot in the slow scan direction of the image plane including a light source capable of emitting the beam of light at a selected one of at least two selectable wavelengths and beam deflecting means for deflecting the beam of light an amount which depends on the wavelength of the beam of light, the amount of deflection determining the position of the spot in the slow scan direction on the image plane. The light source may be of the solid state laser type, and may emit a plurality of beams of light the spots from which may be individually or together selectively positioned in the slow scan direction on the image plane. The beam deflecting element may be a semiconductor prism, for example of AlGaAs, and have a controllable bias applied thereto to allow further control of spot positioning.

Abstract: A multi-directional bar code reading device for reading an object that is to be read by projecting scanning beams from many directions, includes a plurality of mirrors (2) arranged around a beam scanning unit (1) and a plurality of beam sources (3) for emitting beams toward said beam scanning unit (1). The beam scanning unit (1) is irradiated with beams generated from the plurality of beam sources (3), scanning beams are reflected by the plurality of mirrors (2) and are projected from a plurality of directions onto an object (5) to be read, and light reflected from the object (5) is detected in order to read bar codes on the object (5) to be read.

Abstract: In an optical output device wherein a beam of light is generated and focused to a spot upon an image plane, such as a photoreceptor in a xerographic printing apparatus, an method for controlling the position of the spot in the slow scan direction of the image plane including the steps of generating a beam of light, deflecting the beam of light by way of an optical beam deflecting elements such that the optical beam deflecting element deflects the path of the beam of light by an amount that is determined by the wavelength of the light beam, and varying the wavelength of the beam of light such that the amount that the beam of light is deflected by the optical beam deflecting element is varied to achieve control of the position of the spot at which the beam of light is incident on the image plane in the slow scan direction.

Abstract: In a symbol reading device, at least two laser beams having different optical path lengths, and, therefore, different focal positions are used to scan a symbol surface. The two laser beams are produced from a single beam issuing unit, and only one beam at a time scans the symbol surface. Furthermore, stationary reflecting mirrors are used to create the two laser beams of different focal length, reducing the number of moving mechanisms and the overall complexity of the device.

Abstract: An optical system and method for data reading including a light source which generates an optical beam directed toward an object, a pivoting scan mirror which directs the optical beam over a scanning range on the object to be read, a stationary collection mirror for collecting light from the object, a fold mirror positioned behind the scan mirror for reflecting light collected by the collection mirror through an aperture in the collection to a photodetector.

Abstract: An optical scanning apparatus includes a light-shielding member, disposed between an optical deflection unit and a converging lens, for shielding a scanning beam incident on an edge portion of the converging lens on the scanning starting position side, and the apparatus converts a laser beam into a scanning beam by the optical deflection unit and raster-scans a photosensitve material with the scanning beam through the converging lens to form an image on the photosensitive material. The apparatus may further include a deflection mirror with another light-shielding member, disposed between the converging lens and the photosensitive material, for guiding the scanning beam which does not contribute to image formation immediately after starting of the scanning to a scanning beam detection unit. In the optical scanning apparatus, occurrence of a stray light can be prevented owing to the light-shielding member, whereby an image of high quality free from uneveness of an image or blurring of an image can be formed.

Abstract: In a variable density scanning apparatus, a variable focal distance device is provided in a scanning optical system. This variable focal distance device is formed of a light waveguide having a plurality of electrodes, of which the lengths along the direction of an incident laser beam are decreased or increased with the increase of the distance from the central electrode. The voltage to be applied between the electrodes is controlled in accordance with a desired dot pattern so as to change the refractive index of the light waveguide through which the laser beam is passed, thereby effectively changing the focal distance so that the diameter of the scanning laser beam spot can be changed in one dimension.

Abstract: An optical scanning unit which employs a mirrored spinner and a plurality of pattern mirrors that counter rotate to produce an omnidirectional scan pattern having a predetermined depth of field. The pattern mirrors are mounted within a drum which rotates freely within the scanner housing. The optical scanning unit employs a variable drive gear mechanism to counter rotate the spinner and pattern mirrors using a single motor. The optical scanning unit additionally employs a collection filtering system for filtering Fresnel reflections from light reflected from an article having a bar code label to be scanned. A plurality of scanning units may be arranged vertically or horizontally to form a multiple depth-of-field optical scanner.

Abstract: A scanner system includes a light source for producing a light beam and a scanner for directing the light beam to a spot on a surface to a be scanned and for moving the spot across the surface along a scan line of predetermined length in a series of scan cycles. A reference clock produces a train of M reference pulses during each of the scan cycles such that each of the reference pulses represents the occurrence of a respective one of M segments of the scan cycle. An oscillator produces a train of clock pulses for use in controlling the light beam at a predetermined number of desired pixel positions along the scan line while a frequency control circuit responsive to the reference pulses varies the frequency of the oscillator during the occurrence of each of the M segments of the scan cycle in order to approximate an ideal frequency variation curve the entire scan cycle.

Abstract: A scanning device has a drive system to angularly reciprocate a rotatable mirror about an axis in a desired waveform in accordance with an excitation signal supplied by a programmable waveform generator. A position sensor generated as signal representing the actual waveform of reciprocation of the mirror, and a microprocessor determines a signal representing the error between the actual waveform and the desired waveform. The microprocessor includes a waveform optimizer that receives this error signal and delivers an excitation correction signal to the waveform generator to adjust the excitation signal from the waveform generator to cause the mirror to have an actual waveform substantially in accordance with the desired waveform.

Abstract: A beam scanning apparatus for scanning light beam on a scanning surface, has a deflector, a scanning mechanism, a detector and a controller. The deflector deflects the light beam so as to guide it to the scanning surface. The scanning mechanism functions to change at least one of a deflection angle and a deflection position of the deflector so that the light beam is scanned on the scanning surface. The detector detects the scanning state of the light beam by the scanning mechanism on the scanning surface by receiving the light beam from the deflector. The controller corrects at least one of the deflection angle and the deflection position of the deflector on the basis of the detection result of the detector.

Abstract: A laser film scanner scans film as it is translated in a substantially horizonally plane past a diffuse light collector. The light collector includes an elongated housing enclosing a collection cavity having a slot at its top through which light enters. The cavity has diffuse reflective surfaces to diffusely reflect light to a photodetector communicating with the cavity. Positioned opposite the slot is a slanted face from which light entering the cavity is directly reflected. The slanted face avoids streak artifacts in a detected image by permitting dirt particles falling through the slot to roll down to a lower region in the cavity. The slaned face may be formed from a removable insert of low adhesion fluorocarbon material to permit cleaning without disassembling the collector.

Abstract: A polygon for reading and writing information, and for tracking industrial products on a rotating carousel is arranged so that each of its sides behaves effectively like a mirror mounted directly on a rotational axis of the polygon. When this polygon is installed in the center of rotating carousel, it can perform accurate tracking of objects on the carousel with a constant (fixed) rotational speed equal to half of the rotational speed of the carousel. One design employs a polygon with side mirrors tilted in an arbitrary angle with surrounding mirrors (opposite-side mirrors) tilted at a right angle with respect to the tilted side mirrors of the polygon (FIG. 12). Additional designs are of polygons with side mirrors tilted at an arbitrary angle .alpha. and opposite-side mirrors tilted at an angle .alpha./n (where n is an integer) with respect to the tilted side mirrors of the polygon. Such a polygon is illustrated in FIG. 11 for n=1 (.alpha.=.beta.=45 degrees).

Abstract: A polygon (FIGS. 4to 6) has unique physical dimensions, i.e., its radius (R8') is correlated to a tracking radius (R13')(where objects are scanned) by a rule which creates an improved linear tracking system with a constant optical path. The polygon is very useful for reading information, writing information, and tracking industrial products on a rotating carousel. When the polygon is mounted on the center of a rotating carousel, with no relative movement between the polygon and the carousel, it can perform accurate linear tracking of objects located on the carousel. The radius of the polygon is equal to half the tracking radius divided by the cosine of an angle of 180/n {Eq. (6)}, where n is an integer. The polygon can have an arbitrary number of sides. Using another method, the non-linearity of the system for an arbitrary polygon's radius can be corrected by a series of sensors [N1 to N4, FIG.

Abstract: A focus changing apparatus and method for an optical scanner which can easily be adapted to existing optical scanners or can provide the front end for a new scanner. The laser beam focus changing apparatus may be optically located between a laser source and a mirrored spinner and includes a plurality of spherical mirror segments having a predetermined radius. Each is located at its respective radius from a common axis. A rotating device, such as a motor, rotates the spherical mirror segments about their common axis. The spherical mirror segments may be mounted on top of the mirrored spinner. If so, the focus changing apparatus may additionally include a deflector mirror for deflecting the beam towards the spherical mirror segments and a spherical mirror adjacent the deflector mirror is optically located to receive the beam after it is reflected from the spherical mirror segments and to redirect the beam towards the mirrored spinner.

Abstract: A scanning device comprises a rotatable mirror and a drive unit. The drive unit comprises a rotor section which carries the mirror and which is rotatable about an axis of rotation (19), which rotor section has a disc-shaped at least partly permanent-magnetic rotor body (13). The drive unit further comprises a stationary stator section with coils (9) extending in the magnet field of the rotor body to generate electromagnetic driving forces acting on the rotor body to provide the rotary drive of the mirror, and coils (11) disposed in the magnet field of the rotor body to generate electromagnetic bearing forces acting on the rotor body, for electromagnetically supporting the rotatable rotor section relative to the stator section.

Abstract: A scanner for reading indicia on a member, surface, sheet, or similar object. Several laser diodes are used to separately generate laser beams which are scanned across the member as separate beams. The light spots produced by the beams on the member are not coincident with each other. Light reflected from the scanned member is imaged onto a linear CCD array which combines or integrates the reflected light produced by each spot to produce the resulting data for the corresponding location. Controlling the output of the laser diodes can customize the overall wavelength of the scanning light and the energy profile of the light across the scan. Some component tolerances of the system are reduced because less than the entire light spot is used to illuminate an area imaged onto the CCD sensors.

Abstract: A surface inspecting apparatus generates an inspecting width gate signal by in a procedure wherein when the subject matter is subjected to the scanning via the light beam, a counting means digitizes the detected position of both the front and rear ends of the subject and then an operating means calculates values which indicate the positions included within the range between both of the ends, thus generating the inspecting width gate signal. Consequently, it is possible to inspect any subject matter without manually resetting the effective inspecting range whenever a subject matter changes in width.

Abstract: In an optical unit used for a laser beam printer, a laser beam generated by a laser diode is converted by a group of conversion lenses into a laser beam having a predetermined-size cross section. The laser beam is directed toward a photosensitive body by a scanner. A focusing lens allows the rotating angle of the reflecting faces of the scanner to correspond to a desirable point on the surface of the photosensitive body. In other words, the rotating angle is made to correspond to the distance between the optical axis center determined with respect to a main scanning direction and a point to which the laser beam is irradiated for scanning. The conversion lenses includes at least one aspheric glass lens arranged close to the laser diode. The glass lens and the laser diode are integrally held by a lens barrel which linearly expands in a predetermined manner in response to a temperature change.

Abstract: A multi-beam optical system is provided with reflecting mirrors and separating mirrors on optical paths of light beams for each color so that the difference of the numbers of reflections of the scanned light beams for the respective colors when they penetrate through the lens and reach the photosensitive drum can be the same or an even number. The ference of the number of reflections of the scanned light beams for the respective color can become an even number and the scanning lines are distorted in the same direction by the lens, and are thus not liable to lose a parallel relation between the line images.

Abstract: A post-objective type optical scanner in which optical flux is converted to condensed light or diffused light by a lens and then scanned on a scanning surface by an optical deflector is constituted by a light source, an optical scanner for leading the flux of light from the light source to an optical deflector and an optical deflector which has a toric deflecting surface in which the radius in the scanning direction is convex and the radius in the sub-scanning direction is concave, and which compensates the curvatures of field in both scanning and sub-scanning directions and scans the optical flux by rotation.

Abstract: A photosensor (20a) has a pair of n-type semiconductor layers (21U, 21D) formed on the major surface of a p-type semiconductor substrate (31). A light-shielding pattern (24) comprised of unit light-shielding layers (33) is formed on the major surface of the substrate. When the major surface is scanned by a light beam in the direction (D.sub.X) in which the unit light-shielding layers are aligned, a couple of photo-conversion signals indicating a current position of the light beam on the photosensor are generated in the photosensor. Since the light-shielding pattern is directly provided on the sensor body, no grating glass is required other than the photosensor.

Abstract: A multiple diode laser ROS scanning system is modified to eliminate the need for buffering scan lines so that they can be brought into the required adjacent lines at a photosensitive surface. The wavelength of the diode outputs are selected such that each diode differs from the other within a selected range. The beams are collimated and directed through a dispersive element such as a prism which is positioned so as to cause the beams to converge towards each other. After reflection from a reflective facet surface of a polygon, the beams are swept across the surface of an image media as adjacent scan lines.

Abstract: The present invention relates to scanning devices, for example those used in image scanning, observation and watching systems or else those used for example in aerial reconnaissance. The invention consists essentially in causing the mirror M to rotate about an axis distinct from the perpendicular to the plane of the rotating beam. In particular, this axis of rotation is set to an angle with respect to the perpendicular to the plane of the rotating beam, this angle being itself a function of the angle of incidence of the light beam.

Abstract: A light beam passing through a first image-forming system is deflected by a deflector. The deflected light impinges upon a second image-forming system which comprises a scanning lens and an anamorphic lens. The scanning lens and the anamorphic lens are disposed in this order from the deflector side. The light beam passing through the anamorphic lens is finally focused on a surface to be scanned with no curvature of field.

Abstract: A confocal scanning microscope operates to produce a small (preferably diffraction limited) spot on a sample, scan the spot over the sample in a raster pattern, and form an electrical signal corresponding to the intensity of light emanating from the region of the spot. The electrical signal is communicated to a computer which produces a visual display on a monitor. The optical train between the source (or detector) and the sample comprises first and second scanning elements, each operable to scan the beam in a different direction, an afocal assembly located between the two scanning elements so as to transfer the beam from the first scanning element to the second scanning element, and standard microscope components including an objective. The light emanating from the sample encounters the objective, the scanning elements, and the afocal assembly prior to reaching the detector. An aperture is disposed in front of the detector and blocks any light that emanated from points spatially displaced from the beam spot.

Abstract: The efficiency of a raster output scanning system is enhanced by replacing a folding mirror cylindrical lens in the pre-polygon optics with a single cylindrical mirror. The mirror is designed and positioned to direct a beam input in a different direction along an optical path and to focus the beam in the sagittal plane at an optimum line at the facet surface. The mirror is arranged so that the focus line is parallel to the angle the mirror makes with the system optical axis and coincident with the vertical plane of the polygon facets upon which it impinges.

Abstract: In an optical unit used for a laser beam printer, a laser beam generated by a laser diode is converted by a group of conversion lenses into a laser beam having a predetermined-size cross section. The laser beam is directed toward a photosensitive body by a scanner, so as to scan the photosensitive body at a constant speed. A focusing lens allows the rotating angle of the reflecting faces of the scAnner to correspond to a desirable point on the surface of the photosensitive body. In other words, the rotating angle is made to correspond to the distance between the optical axis center determined with respect to a main scanning direction and a point to which the laser beam is irradiated for scanning. The focusing lens is arranged between the scanner and the photosensitive body and shapes the laser beam reflected by the scanner such that the laser beam has a desirable diameter.

Abstract: A scanning thermal imager includes means to compensate for a degree of undesirable asymmetry introduced by an element such as a spherical lens operating in an off axis manner. The means can advantageously include an optical element mounted in the optical path with at least one main face at an angle other than normal to the path and arranged to introduce a desired degree of compensating asymmetry.

Abstract: The imaging and illumination system with aspherization and aberration correction by phase steps includes two transparent phase plates within the optical train of a stepper illumination system. The first plate places each ray at the corrected position on the axial stigmatism plate to satisfy the sine condition. The second plate, which is the axial stigmatism plate, ensures that each ray of light focuses at the focal point. The aberration corrected light is reflected by a deformable mirror toward a secondary mirror, a primary mirror and finally onto a wafer to project a single field of large dimension. The secondary and primary mirrors provide aspherization by forming phase steps in the surfaces of the mirrors. The deformable mirror, to permit realtime correction of aberrations and manipulation of the beam for each field imaged by the system. A set of two-dimensional scanning mirrors is placed between the laser light source and a reticle containing to pattern which is to be transferred to the wafer.

Abstract: A scanning optical system projects a light beam from a light source as a line spread function image in a principal scanning plane before the light beam is made incident onto a scanning deflector. A static deflector is disposed in a line spread function image position in order to guide a light beam from a light source to the scanning deflector. The static deflector has a slit mirror for reflecting a light beam from the light source or a mirror with a slit for permitting a light beam to be transmitted therethrough.

Abstract: The improved light beam scanning apparatus uses a simple and inexpensive focal point adjusting device to adjust the optical path lengths of a plurality of light beams having different wavelengths so that their focal lengths will coincide with each other. This permits not only a number of optical members in the main scanning optics to be used in common for the plurality of scanning beams but also the sub-scanning transport mechanism to be used in common for more than one kind of object to be scanned. Accordingly, the light beam scanning apparatus is compact and inexpensive and yet is capable of scanning to read image information from plural kinds of objects or to record image information on plural kinds of objects or to read and record such information from more than one object to be scanned.