Abstract: An image forming apparatus for forming images with an electrophotographic system. The image forming apparatus includes a laser drive unit configured to control a laser light, and an image data transfer control unit configured to control image data from to the laser drive unit. The apparatus also includes a polygon mirror configured to reflect laser light from the electrophotographic system, a polygon mirror drive unit including a motor configured to rotate the polygon mirror, and a power supply level detecting unit configured to detect a voltage level of power supplied to the polygon mirror drive unit by an electric power supply unit. The image data transfer control unit is configured to provide any width and any number of a first pulse signal indicating a state when power supply is cut off to the polygon mirror drive unit.

Abstract: An apparatus for forming an image is disclosed which includes a scanner motor rotatably driving a polygon mirror; a laser light emitter emitting laser light; a generator detecting the laser light reflected off from the polygon mirror, thereby generating a first periodic signal; a generator detecting rotation of the scanner motor, thereby generating a second periodic signal; and a controller performing speed control of the scanner motor, based on at least one of the first and the second periodic signal. The controller makes a first determination as to whether a pre-selected one of the first and the second periodic signal is abnormal. Upon the pre-selected signal being abnormal, the controller makes a second determination as to whether a remaining one of the first and the second periodic signal is normal, and based on a result of the second determination, the controller identifies at least one failed element of the apparatus.

Abstract: An optical scanning apparatus includes a light source device, a rotating polygon mirror, a first optical system, and a second optical system. The light source device has at least one light emitter. The first optical system can cause a light beam emitted from the light source device to be incident on the rotating polygon mirror. The width of the incident light beam is larger than the width of the deflecting surface of the rotating polygon mirror in the main scanning direction. The second optical system leads the light beam deflected by the rotating polygon mirror to a surface to be scanned. The surface to be scanned is scanned with the light beam in the main scanning direction by the rotation of the rotating polygon mirror. The number of the deflecting surfaces of the rotating polygon mirror is ten or less, and each conditional expression is satisfied.

Abstract: Provided is a light scanning apparatus, including a light source, a light source controller to control an on/off operation of the light source, a light deflector deflecting light emitted from the light source, an image formation optical system to direct light deflected by the light deflector on a scan area of a to-be-scanned surface, a synchronous signal detector to receive the light emitted from the light source and to detect a synchronous signal for light scanning, and a light path changer changing a path of light emitted from the light source and incident upon the light deflector.

Abstract: A light scanning apparatus has a base member, a first engagement portion that engages with a bearing member having a bearing portion of a rotary shaft that rotates a rotational polygon mirror to thereby position the bearing member, a second engagement portion that engages with a bearing member having a bearing portion of a rotary shaft that rotates a rotational polygon mirror to thereby position the bearing member, and a positioning portion in which the first engagement portion and the second engagement portion are integrally formed, the positioning portion being provided on the base member. With this structure, a common base member can be used in optical units, and even when rotational polygon mirrors are supported on different surfaces of the base members of optical units, a difference in precision of support can be made small.

Abstract: An image forming apparatus includes an intermediate transfer member position detection unit configured to detect a position of the intermediate transfer member to output an image forming operation start signal, a pattern detection unit configured to detect a registration correction pattern formed on the intermediate transfer member based on the image forming operation start signal, a misregistration variation detection unit configured to read the registration correction pattern detected by the pattern detection unit based on the image forming operation start signal and to generate a reference clock signal based on the read registration correction pattern, and a polygonal mirror drive motor control unit configured to adjust a rotation speed of the polygonal mirror drive motor based on the reference clock signal generated by the misregistration variation detection unit.

Abstract: The present invention relates to a scanning apparatus for a laser printer. More particularly, the present invention relates to a scanning apparatus, which is formed to allow a light modulator to be non-perpendicular to the shaft of a photosensitive drum, which is a scanning object, thus performing scanning at a higher resolution and speed within the allowable limits of other devices. The scanning apparatus of the present invention includes an optical means, a rotating mirror, a conversion means, and a drum-shaped scanning object.

Abstract: The present invention uses a pattern that enables image quality maintaining control to be performed at a resolution lower than that used for a normal image forming process. Thus, during an initial operation upon power-on, the image quality maintaining control is performed at the resolution lower than that used for the normal image forming process.

Abstract: The over-field type optical scanner includes a first imaging optical system disposed between a light source and a rotating polygon mirror for forming, on one surface of the rotating polygon mirror, a linear image with a width larger than a width along a main scanning direction of the one surface of the rotating polygon mirror; and a second imaging optical system composed of a curved mirror for focusing, on a scan surface, a light beam having been reflected by the rotating polygon mirror. The first imaging optical system includes a first conversion optical system for converting the light beam emitted from the light source into a divergent light beam with respect to the main scanning direction and into a convergent light beam with respect to the sub scanning direction; and a second conversion optical system having a refracting power in the main scanning direction.

Abstract: A polygonal mirror unit is adapted to prevent contamination using a photocatalyst, a light scanning unit, and an image forming apparatus employing the polygonal mirror. The polygonal mirror unit is designed to prevent contamination of organic materials on a reflective surface. The polygonal mirror unit includes a driving device and a polygonal mirror having a reflective surface that is rotated by the driving device and deflects and scans an incident beam. The polygonal mirror has a main body with a plurality of reflective surfaces and photocatalytic layers formed on the plurality of reflective surfaces. The photocatalytic layers are activated by an incident beam of a predetermined wavelength to decompose organic materials on the reflective surfaces.

Abstract: In order to determine an arrangement of an optical scanning device provided with a rotary polygon mirror having a plurality of reflective faces, it is determined a direction of polarization of light which is to be made incident on one of the reflective faces and to be reflected and deflected in accordance with a rotary action of the polygon mirror; and it is determined a direction from which the light is made incident on the one of the reflective faces, such that a variation of reflectivity of the light depending on a variation of an incident angle thereof in accordance with the rotary action of the polygon mirror compensate for a positional variation of reflectivity on the one of the reflective faces.

Abstract: A rotary apparatus for a polygon mirror has: a sleeve; a rotation shaft which is inserted into the sleeve; the polygon mirror which is fixed to the rotation shaft; a yoke which is fixed to the rotation shaft; permanent magnets which are fixed to the yoke; and a stator which is fixed to the sleeve, and which is opposed to the permanent magnets. Tapped portions are formed in a part of the outer circumference of the rotation shaft, and a part of the inner circumference of the sleeve, respectively. The tapped portions are temporarily engaged with each other in a process of inserting the rotation shaft into the sleeve. The rotation direction of the rotation shaft in a driving process is identical with that of the rotation shaft in the inserting process.

Abstract: A motor drive device for driving of a plurality of motors in a proper manner, having a first motor, a second motor, and a current controller. The first motor is able to drive at up to a first maximum permissible current of A1. The second motor is able to drive at up to a second maximum permissible current of B1. The power supply supplies up to a maximum permissible supply current of D to the first and second motors. The current controller controls operations of the first and second motors. The maximum permissible supply current of D is set to be less than a sum of A1 and B1. The current controller controls a first current A2 to be supplied to the first motor and a second current B2 to be supplied to the second motor so that a sum of the first and second current A2 and B2 is less than D. The current controller controls the second current B2 to be less than the second maximum permissible current B1.

Abstract: A light beam scanning apparatus that causes a beam generated by a light source to scan corresponding to recording direction along a photosensitive medium by rotating polygonal mirrors, wherein to form a latent image on the photosensitive medium, comprising a first polygonal mirror that rotates at a first velocity, a second polygonal mirror that rotates at a second velocity different from the first velocity, and a controller that carries out image formation by selectively using the first polygonal mirror and the second polygonal mirror.

Abstract: An image forming device, characterized in that the shape of the optical path of a third laser beam from a third semiconductor laser (19M) to a third photo-sensitive member drum (IM) is approximately the same as that of the optical path of a first laser beam from a first semiconductor laser (19C) to a first photo-sensitive member drum (1C), a second virtual line connecting the rotating center of the third photo-sensitive member drum (IM) to the rotating center of a fourth photo-sensitive member drum (IK) is tilted relative to a first virtual line connecting the rotating center of the first photo-sensitive member drum (1C) to the rotating center of the second photo-sensitive member drum (IY), and an angle formed by the rotating axis (x2) of a second rotating polygon mirror (20b) and the second virtual line (12) is equal to an angle formed by the rotating axis (x1) of a first rotating polygon mirror (20a) and the first virtual line (11).

Abstract: An optical scanner for an image forming apparatus of the present invention includes a polygonal mirror for steering a scanning beam incident thereto and an optical device located in the vicinity of the polygonal mirror. The polygonal mirror and optical device are supported by a housing. A heat radiation guide adjoins the polygonal mirror and is formed integrally with or separately from the housing. The heat radiation guide has a guide surface inclined relative to the axis of rotation of the polygonal mirror and intersecting a plane virtually formed by a scanning beam.

Abstract: An effective scanning range of laser light in a scanning direction is configured so that a center position of the effective scanning range is displaced by a distance ? along the scanning direction from an optical axis f an f? lens. The incidence angle ? between a center of luminous flux of the laser light on a deflection surface of polygon mirror and the optical axis of the f? lens can beset to satisfy a relational expression (4?/N)?(W/D)?|?|<(4?/N)?{(W??)/D}.

Abstract: An optical scanning apparatus includes a light source that emits a light beam, optical systems through which the light beam travels including one that forms a line image, a polygon mirror that rotates and deflects the light beam with a deflective reflection surface, and a scanning optical system that converges the light beam to scan a target surface with a light beam spot. The optical system closer to the light source than the polygon mirror is configured so as to correct a change in an image-forming position of the light beam spot caused by deformation of the deflective reflection surface originating from the rotation of the polygon mirror.

Abstract: A polygon mirror including a plurality of reflection surfaces. Each reflection surface has a writing region and two non-writing regions. The writing region includes a first reflecting section and a second reflecting section positioned downstream of the first reflecting section in a rotating direction of the polygon mirror. One non-writing section is positioned at an upstream end of each reflecting surface, and the other non-writing region is positioned at a downstream end of each reflecting surface. The first reflecting section has a reflection factor higher than a second reflection factor of the second reflecting section. A foggy region appears in the first reflecting section.

Abstract: An optical scanning frequency doubling method and apparatus adopting the same are provided. According to the method and apparatus, light scanned by a mirror to a predetermined region is fed back to the mirror. The fed back light is output through an output region. Thus, the frequency of a scanner is doubled, thus greatly overcoming difficulties in high-frequency scanning that current scanners employing a separate optical feedback structure have. That is, the apparatus and method optically double the frequency given by the physical structure of the scanner. The doubled frequency is very suitable for laser televisions, and in particular, for high resolution and high quality laser projection-type image display devices.

Abstract: A scanning optical system comprises: a light source which emits a beam of light; a deflecting system that dynamically deflects the beam emitted by the light source with its deflecting surface; and a scan lens group including a molded resin lens, which focuses the beam dynamically deflected and scanned in a main scanning direction by the deflecting system on an image formation surface. In the scanning optical system, the molded resin lens has a diffracting lens surface which is provided with a diffractive level difference structure formed on a base curve having refractive power, and a following condition is satisfied: 18<WL/P<28 where “W” denotes an effective scan width (mm) on the image formation surface, “L” denotes a distance (mm) from the deflecting surface to the molded resin lens, and “P” denotes a distance (mm) from the deflecting surface to the image formation surface.

Abstract: A width in a main scanning direction of a laser beam is decreased in the outside of an effective scanning region in such a manner that the width along the main scanning direction of the laser beam is restricted by an aperture portion of an aperture member. As a result, so-called flare light is prevented from generating, and a uniformity of light quantity is improved. Namely, in a light scanning apparatus adopting an overfilled optical system, a light scanning apparatus which can prevent degradation of image quality due to flare light is obtained.

Abstract: In an optical scanning apparatus having a light source, an incidence optical system for causing a beam emitted from the light source to be incident on a deflector, an imaging optical system for causing the beam reflected and deflected by the deflector to be imaged on a surface to be scanned, and a reflecting portion having a plurality of substantially plane reflecting mirrors disposed in an optical path between the deflector and the surface to be scanned, the reflecting portion includes a reflecting mirror of which the refractive power in a main scanning cross section is of an opposite sign. Provided are an optical scanning apparatus which does not involve structure and work for adjustment, and can obtain stable imaging performance by a simple method even if a plurality of mirrors are disposed, and an image forming apparatus using the same.

Abstract: A scanning optical system deflects a light beam by a reflection surface of a polygon mirror toward an object surface through an image forming optical system so that the light beam scans on the object surface to form an image thereon. A light shielding member is disposed between the polygon mirror and the image forming optical system. The shielding member is an opaque plate disposed perpendicular to the optical axis of the image forming optical system. The light shielding member prevents a ghost light that is reflected by another reflection surface of the polygon mirror located adjacent to the reflection surface deflecting the light beam from entering the image forming optical system and impinging onto the object surface.

Abstract: This invention has as its object to provide an image forming apparatus in which the number of beam detectors is decreased and which is low in cost and high in the accuracy of the registration position of an image of each color as well as high in quality.

Abstract: An optical beam scanning device includes plural light sources, a pre-deflection optical unit, a light deflection unit, a post-deflection optical unit, and a horizontal synchronization unit. One of the formed plural latent images is formed by plural light beams while the other latent images are respectively formed by one light beam, and the light deflection unit deflects the light beams forming the plurality latent images by one surface or integrally processed surface thereof. The horizontal synchronization unit is on a position of an upstream side of scanning lines forming the latent image formed by the plural light beams and deflects that the light beam forming the latent image formed by the plural light beams reaches a predetermined position. The image forming apparatus employs the optical beam scanning device and controls timing to form images by the respective light beams with reference to a moment when the light to be detected reaches a predetermined position.

Abstract: The present invention provides a device for forming an image on a photoconductive image carrier in an image forming apparatus. The device comprises a light source for generating a light beam, an aperture for shaping the light beam generated by the light source, a deflector (polygon mirror) for deflecting the light beam shaped by the aperture, and an optical scanning imaging part for focusing the light beam deflected by the deflector onto the photoconductive image carrier as an optical spot and forming an image thereon. The deflector is provided with at least one blocking member (first blocking plate) for blocking flare beams that do not contribute to image formation. Further blocking members (auxiliary blocking plate and second blocking plate) may be provided to stationary parts of the device so as to block leaked light beams.

Abstract: A laser printer having a rotating mirror (116) and a heat fuser (220) is operated with a sequence of standby conditions. At the end of a print job mirror (116) is continued to be rotated at printing speed while the temperature of fuser (220) is reduced somewhat. This is maintained for a short time, after which the speed of rotation of mirror (116) is reduced significantly and the fuser (220) temperature is reduced significantly. This is maintained for a time, after which the mirror is no longer rotated (or, if practical, is rotated very slowly) and the fuser temperature is further reduced. At any time when a subsequent print job is received, the mirror and fuser are brought to printing state and the period of times are next started from a beginning state.

Abstract: An optical scanner for an image forming apparatus of the present invention includes a polygonal mirror for steering a scanning beam incident thereto and an optical device located in the vicinity of the polygonal mirror. The polygonal mirror and optical device are supported by a housing. A heat radiation guide adjoins the polygonal mirror and is formed integrally with or separately from the housing. The heat radiation guide has a guide surface inclined relative to the axis of rotation of the polygonal mirror and intersecting a plane virtually formed by a scanning beam.

Abstract: A laser scanning unit includes a housing; an optical system disposed in the housing and including an optical source which emits a laser beam, a polygonal mirror which scans the laser beam, and a plurality of optical elements which image the laser beam on an image surface; a motor disposed in the housing and which rotates the polygonal mirror; and a motor drive chip disposed outside of the housing and which uses a sensorless algorithm to control a rotation speed of the motor.

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

Abstract: A device for holding a laser diode (LD) and a collimate lens. A laser unit includes an LD supporting section supporting the LD, and a lens supporting section supporting the lens positioned opposite to the LD, A connecting portion connects the lens supporting section to the LD supporting section. An adjustment section for adjusting a relative position between the LD and the lens is provided in association with the LD supporting section. The adjustment section allows the LD supporting section to be movable and position-fixable with respect to the lens supporting section as if the LD supporting section serves as a leverage about the connecting portion functioning as a fulcrum.

Abstract: An optical deflection device having a rotary body that is fixed on a bearing and is structured rotatably by a magnet arranged to face a coil provided on a base side, wherein the rotary body is made of a magnet and a polygon mirror is fixed on the rotary body.

Abstract: A passive, stable optical system whose temperature is actively regulated is best suited to prevent color fringes in high-speed recorders for digital color images. Peltier elements (14) are well suited as actuators for active temperature regulation. They allow for temperature stabilization of both rapid heating and cooling of the components and housing (10) of an optical module (1) of a high-speed recorder. The overall design of the module (1) must be adapted for each individual application of the Peltier elements (14).

Abstract: A width in a main scanning direction of a laser beam is decreased in the outside of an effective scanning region in such a manner that the width along the main scanning direction of the laser beam is restricted by an aperture portion of an aperture member. As a result, so-called flare light is prevented from generating, and a uniformity of light quantity is improved. Namely, in a light scanning apparatus adopting an overfilled optical system, a light scanning apparatus which can prevent degradation of image quality due to flare light is obtained.

Abstract: In a disclosed image forming device, the directions of light sources at installation and the numbers of returning mirrors are set such that a plurality of optical beams emitted from multi-beam lasers in which light-emitting sections are two-dimensionally arranged have the same directions for the two dimensional axes on each of corresponding photosensitive bodies Each of a main scanning direction and a sub-scanning direction on the photosensitive bodies has the same direction as each direction of the main scanning axis (for example, the X axis) and the sub scanning axis (for example, the Y axis) of each optical beams.

Abstract: A dynamic pressure bearing apparatus having high performance and excellent stability without hindering operations of appliances due to a leaked oil, the dynamic pressure bearing apparatus including: a rotating shaft inclined in a predetermined direction from a vertical direction; a sleeve rotatably supporting the rotating shaft; an operating fluid for generating a dynamic pressure, the operating fluid being filled in a gap formed between the sleeve and the rotating shaft; and a capturing device for capturing the operating fluid leaked from the gap, the capturing device being disposed on an outside surface of the sleeve in the predetermined direction.

Abstract: An optical scanning apparatus provides improved image quality by changing the amount of writing scale compensation for a pixel clock during a scanning cycle. A pixel clock generation unit of the optical scanning apparatus divides the scanning cycle into multiple division periods. A phase change of the pixel clock is carried out for each of the division periods. The phase change can also be different from scanning cycle to scanning cycle.

Abstract: A laser beam pattern generator has a substrate support capable of supporting a substrate, the substrate support having a support motor capable of moving the substrate support. A laser beam source is provided that is capable of generating a laser beam. A beam modulator is also provided that is capable of modulating the intensity of the laser beam according to a pattern. A rotating scanner is provided that has a plurality of mirror facets capable of rotating at a spinning frequency to scan the laser beam across the substrate. The laser beam pattern generator also has a rotating scanner compensator to deflect the laser beam according to a rotating scanner correction signal containing a harmonic of the spinning frequency to compensate for errors in the scanning of the laser beam arising from the rotating scanner.

Abstract: A light-scanning optical system having a function of correcting surface tilt comprises a light source 11; a first optical means 1; a light-deflecting means 14 for reflecting and deflecting a luminous flux by its deflecting/reflecting surface 15 so as to scan a surface to be scanned 18; a first lens 16 having a positive refracting power in each of the main scanning and sub-scanning directions, in which each of both sides is made of a toric surface; and a second lens 17 having a small negative refracting power, in which each of both sides is made of an aspheric surface. A semiconductor laser having a wavelength of 500 nm or shorter is used as the light source. The first and second lenses 16, 17 may be made of plastic. Thus, in a simple configuration, the light-scanning optical system can reduce its size and cost, while being able to respond to higher image density.

Abstract: An optical system particularly useful for color laser printers. Four imaging systems are provided, one for each color, black, magenta, cyan and yellow. Each imaging system has separate pre-scan and post-scan optical assemblies. Two scanning polygons are provided, and each scanning polygon is shared by two imaging systems. Both pre-scan optical assemblies shared by each scanning polygon are provided on the same side of the scanning assembly at substantially similar mirror image angles, to reduce scan image registration errors. The pre-scan and post-scan optical assemblies have improved adjustability.

Abstract: The present invention provides a device for forming an image on a photoconductive image carrier in an image forming apparatus. The device comprises a light source for generating a light beam, an aperture for shaping the light beam generated by the light source, a deflector (polygon mirror) for deflecting the light beam shaped by the aperture, and an optical scanning imaging part for focusing the light beam deflected by the deflector onto the photoconductive image carrier as an optical spot and forming an image thereon. The deflector is provided with at least one blocking member (first blocking plate) for blocking flare beams that do not contribute to image formation. Further blocking members (auxiliary blocking plate and second blocking plate) may be provided to stationary parts of the device so as to block leaked light beams.

Abstract: A device for treating a substrate with laser radiation is described. The device has a rotating polygon mirror with N reflecting surfaces which are used to direct a laser beam via a system of converting focusing lenses, whereby the focal planes of the lenses are located on a surface of the substrate. Active reflecting surfaces direct the laser beam onto the converging lens system, and subsequently on the substrate, while inactive reflecting surfaces have a different inclination to the active reflecting surfaces in relation to the converging lens system. The laser beam from the surfaces is directed onto an absorber. The large number of inactive reflecting surface helps to reduce serial hole density. When the laser is switched on and off while the inactive reflecting surfaces are being scanned, further reduction of serial hole density can be achieved.

Abstract: An optical scanning apparatus includes an incidence optical system for causing a beam emitted from a light source to be incident on a deflector, and a scanning optical system for causing the beam reflected and deflected by the deflector to be imaged on a surface to be scanned. The scanning optical system has a first lens on the deflector side and a second lens on the surface to be scanned side. The first lens has positive power in the main scanning direction and has negative power in the sub scanning direction. The power of the first lens in the main scanning direction is greater than the power of the second lens in the main scanning direction, and the second lens has positive power in the sub scanning direction.

Abstract: A method and system for diagnosing surface imperfections of an article is provided. A data collection system collects data relating to the surface of the article, and a processor operatively coupled to the data collection system analyzes the surface data to determine deviations in the surface corresponding to surface imperfections and pre-made surface interruptions, and distinguishes between the imperfections and interruptions.

Abstract: A pixel clock generating apparatus comprises a data offset circuit and a pixel generator. The data offset circuit defines multiple data blocks, each data block consisting of a predetermined number of successive clocks, and produces phase data for each data block. The phase data represents an amount and a direction of phase shift to be carried out for a certain clock in each data block. The pixel generator receives the phase data from the data offset circuit and generates a phase-shifted pixel clock a predetermined number of times in each data block based on the phase data.

Abstract: A strip neutral density filter varies the Gaussian intensity profile of the modulated light beam in an overfilled raster output scanner to provide a generally uniform intensity light beam spot at the photosensitive medium. The strip neutral density filter is positioned in the light beam path between the emitting laser source and the rotating polygon mirror of the raster output scanner.

Abstract: An optical scanning device of the present invention includes a light source for emitting a light beam, a rotatable deflector having a plurality of deflecting faces, a first group of optical devices for shaping the light beam issuing from the light source and directing the shaped light beam toward the deflector, and a second group of optical devices for focusing the light beam deflected by the deflector on a surface to be scanned. The second group of optical devices split the light beam into at least two regions and cause each split light beam to scan a particular position on the above surface within a preselected range in the main scanning direction. The optical scanning device is small size and low cost.

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: 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.