Abstract: An image forming apparatus includes: a main casing; a drum cartridge; a toner cartridge; a display; and a controller. The drum cartridge is attachable to and detachable from the main casing. The drum cartridge includes a photosensitive drum and a drum memory. The toner cartridge is attachable to and detachable from the drum cartridge. The toner cartridge includes a toner memory. The controller is configured to: determine whether an error occurs in the drum cartridge through a communication with the drum memory; determine whether an error occurs in the toner cartridge through a communication with the toner memory; and when determining that an error occurs in the drum cartridge and determining that an error occurs in the toner cartridge, display on the display an error relating to the drum cartridge in preference to displaying on the display an error relating to the toner cartridge.

Abstract: Apparatus, methods, and computer-readable mediums are described for adjusting a charge voltage for a photosensitive member to account for accumulated charge quantity. In one example, currents related to charging a charger, which imparts a charge to a photosensitive member, are monitored. Based on the monitored currents, a new charging voltage may be determined and applied that accounts for accumulated charge quantity in the photosensitive member. A transfer current related to a transfer charge may also be monitored or a predetermined value used. The determination of the new charging voltage may be performed at various times.

Abstract: In a flow cytometer, an objective lens for focusing an input laser-radiation beam including at least four different laser-radiation wavelengths in a common plane includes only three singlet lens-elements. Two of the elements are cylindrical elements arranged as a cylindrical telescope for shaping and reducing the size of the input laser-beam. The third element is a spherical element arranged to focus the reduced size beam in the common plane. In one example, all three elements are made from the same optical material.

Abstract: A hand-held therapeutic laser apparatus with a special opto-mechanical construction, which enables changeability of a front collimating lens to create different effective laser apertures. A smaller effective aperture has a comparatively higher radiant flux density for treatment of a small area that requires a higher energy dose, while a larger effective aperture facilitates treatment of a large area at a relatively reduced radiant intensity.

Abstract: Provided is an optical scanning device including a light source, a deflector, a scanning lens, a synchronizing sensor, a sensor lens and a control unit. The deflector causes a scanning line to be written within an effective scanning width of a surface to be scanned. The synchronizing sensor detects a light beam that is outside the range of the effective scanning width on a scanning start side of the scanning line. The control unit controls an emission operation of the light source, and starts the writing of the scanning line at a timing in which a fixed time is added to a timing that the synchronizing sensor has detected the light beam. The sensor lens includes a diffraction grating that bends the light beam in a downstream-side direction of the scanning line, and a bending degree of the light beam by the diffraction grating changes with temperature.

Abstract: A light scanning unit includes a light source unit emitting a light beam according to an image signal, a light deflector scanning the light beam that is deflectively emitted by the light source unit, a housing having a side portion where the light source unit is provided and a base surface on which the light deflector is provided, and a deformation prevention member connecting opposite sides of the housing across an upper side of the base surface. The light scanning unit is employed by an image forming apparatus.

Abstract: A surface emitting semiconductor laser includes a substrate, a first conductivity-type first semiconductor multilayer reflector, an active layer, a semiconductor layer, a second conductivity-type second semiconductor multilayer reflector that includes a current confinement layer, and a heat dissipating metal member. At least the first semiconductor multilayer reflector, the active layer, the semiconductor layer, and the second semiconductor multilayer reflector are stacked in this order on the substrate. A columnar structure having a top portion, a side surface, and a bottom portion is formed from the second semiconductor multilayer reflector to the semiconductor layer. The heat dissipating metal member is connected to the semiconductor layer exposed at the bottom portion of the columnar structure.

Abstract: Provided is an optical scanning device including a light source, a deflector, a scanning lens, a synchronizing sensor, a sensor lens and a control unit. The deflector causes a scanning line to be written within an effective scanning width of a surface to be scanned. The synchronizing sensor detects a light beam that is outside the range of the effective scanning width on a scanning start side of the scanning line. The control unit controls an emission operation of the light source, and starts the writing of the scanning line at a timing in which a fixed time is added to a timing that the synchronizing sensor has detected the light beam. The sensor lens includes a diffraction grating that bends the light beam in a downstream-side direction of the scanning line, and a bending degree of the light beam by the diffraction grating changes with temperature.

Abstract: A light scanning apparatus, including: a first holding member configured to hold a first light emitting element configured to emit a first light beam; a second holding member configured to hold a second light emitting element configured to emit a second light beam; a rotary polygon mirror; a first mounting portion on which the first holding member is mounted; and a second mounting portion on which the second holding member is mounted, the second mounting portion being provided adjacent to the first mounting portion, wherein the first mounting portion has a V-shape including two limbs in a cross section, and wherein one limb of the two limbs on the side of the second mounting portion is shorter than other limb of the two limbs on a side opposite to the side of the second mounting portion.

Abstract: A light beam emission apparatus separates, via a half mirror, apart of a laser beam emitted from a semiconductor laser towards a photosensitive member, guides the separated laser beam to an optical sensor to detect a light quantity, and controls the light quantity based on the detected result. The light beam emission apparatus includes a first light blocking member located between the semiconductor laser and the half mirror, and a second light blocking member located between the half mirror and the optical sensor.

Abstract: An optical scanner includes a light source, an optical part, an enclosure, and a retainer. The light source projects light against a target. The optical part is disposed on a light path between the light source and the target. The enclosure houses the light source and the optical part. The retainer is fixed to the enclosure and includes a plurality of optical part mounts of identical shape and different sizes. The optical part is adhered to one of the plurality of optical part mounts.

Abstract: An optical scanning device includes a pre-deflection optical system including a first optical element that adjusts the shape of beams emitted from the light source; and a second and third optical elements arranged such that the second optical element is arranged closer to the light source than the third optical element is. Both of the second and third optical elements have no refracting power in the deflection scanning direction and have positive refracting power only in a direction perpendicular to the deflection scanning direction. An interval between scanning lines formed on the scanned area and a deviation of the scanning-line interval between scanning positions are adjusted by displacement of the second and third optical elements in a direction of an optical axis of the pre-deflection optical system and displacement of at least one of the second and third optical elements in the direction perpendicular to the deflection scanning direction.

Abstract: A light scanning unit and an electrophotographic image forming apparatus employing the same. The light scanning unit includes an imaging optical system including, when a path of one of the light beams directed to one of the surfaces disposed relatively far from the deflector is referred to as a first light path and when a path of one of the light beams directed to one of the surfaces disposed relatively close to the deflector is referred to as a second light path, light paths in which both of a section of the second light path before a first change of the second light path and a section of the second light path after the first change of the second light path intersect a section of the first light path after a second change of the first light path.

Abstract: A light scanning apparatus, including: a first holding member configured to hold a first light emitting element configured to emit a first light beam; a second holding member configured to hold a second light emitting element configured to emit a second light beam; a rotary polygon mirror; a first mounting portion on which the first holding member is mounted; and a second mounting portion on which the second holding member is mounted, the second mounting portion being provided adjacent to the first mounting portion, wherein the first mounting portion has a V-shape including two limbs in a cross section, and wherein one limb of the two limbs on the side of the second mounting portion is shorter than other limb of the two limbs on a side opposite to the side of the second mounting portion.

Abstract: An optical scanning apparatus, including: a light source; an incident optical system; and an imaging optical system, in which: the imaging optical system includes at least one plastic lens; in a sub-scanning section, principal rays of the beams intersect each other on an optical axis of the imaging optical system; the principal rays intersect each other at different positions between a case of entering a central region of the at least one plastic lens and a case of entering an end region of the at least one plastic lens; and the principal rays entering one of the central region and the end region of the at least one plastic lens intersect each other, and the principal rays entering another of the central region and the end region of the at least one plastic lens intersect each other.

Abstract: An image forming apparatus includes a plurality of optical scanning devices, a mode receiver, a temperature condition judger and a temperature adjuster. In the case of forming an image using one optical scanning device, the temperature adjuster drives motors of unused optical scanning devices at a first rotation speed if a predetermined temperature condition is satisfied and drives the motors of the unused optical scanning devices at a second rotation speed slower than the first rotation speed if image formation is finished during the drive at the first rotation speed.

Abstract: An image forming apparatus includes a plurality of optical scanning devices, a job receiver, a job executor, an image discriminator, a temperature condition judger and a temperature adjuster. When a formation-target image is a single-color image and an image to be formed next is a multi-color image, the temperature adjuster drives a motor of one optical scanning device at a second rotating speed slower than a rotating speed during an image forming operation and drives motors of unused optical scanning devices at a third rotating speed faster than the second rotating speed if a temperature condition is satisfied upon the completion of an image forming operation of the single-color image.

Abstract: A system and method for implementing embedded electronics in environments where radiation or extreme temperatures are used is disclosed. Embedded electronics are affixed to various components of a pharmaceutical system, thereby enabling the customer to download pertinent information about the component, such as lot number, date of manufacturer, test parameters, etc. Additionally, these electronics allow an array of functions and features to be implemented, such as integrity tests and diagnostics. The electronics in the pharmaceutical components utilize a technology that is not as susceptible to radiation and extreme temperatures as traditional electronics.

Abstract: An optical print head having a substrate on which multiple light sources aligned in a main scanning direction are mounted to emit beams of light in a direction perpendicular to a surface of the substrate; a lens array to focus the beams of light on an image bearing member to form an image thereon; a housing having a guiding portion extending in the main scanning direction to position the substrate and the lens array; a cleaner to clean a light-emitting surface of the lens array while moving in the main scanning direction; a moving device to move the cleaner; and a supporting member to support the housing and the cleaner. The supporting member rotatably supports the cleaner about a shaft and the guiding portion contacts the cleaner against the light-emitting surface of the lens array with a constant force over the main scanning direction during cleaning of the light-emitting surface.

Abstract: According to one embodiment, there is provided an imaging element array including an imaging element group in which a plurality of imaging elements are aligned, each of the imaging elements including an integrally molded input portion, an output portion, and a reflective portion, collecting light input to the input portion, reflecting the light by the reflective portion near a position where light flux is downsized, and outputting the reflected light from the output portion to form an image at an image point, and an inhibiting portion which is formed around the reflected portion in the imaging element group to inhibit light other than the light reflected by the reflective portion from traveling to the output portion.

Abstract: An optical scanning apparatus for scanning a target surface using a plurality of light beams simultaneously along a first direction of the target surface. The apparatus has a light source having a plurality of light emitting elements; an optical deflector to deflect the plurality of light beams coming from the light source; and a scanning optical system to guide the plurality of light beams deflected by the optical deflector to the target surface. The scanning optical system includes a lens, disposed after the optical deflector, having the strongest power in a second direction perpendicular to the first direction. A plurality of scan lines, corresponding to the plurality of light beams deflected by the optical deflector, intersect or contact each other at an optical face of the lens.

Abstract: In an exposure device, a light source device having multiple light emitting devices arranged in one-dimensional or two-dimensional directions projects light against an image bearing member. A light source holding member holds the light source device in place. An optical device condenses the light projected from the light source device onto the image bearing member. An optical device holding member holds the optical device to maintain a predetermined gap between the optical device and the light source device on the light source holding member. A positioning member supports the light source holding member above the image bearing member to maintain a predetermined gap between the image bearing member and the light source device on the light source holding member. When seen from a light emitting point of the light source device, a position at which the positioning member supports the light source holding member is opposite the image bearing member.

Abstract: An optical scanning apparatus and an image forming apparatus having the optical scanning apparatus includes a before-light-deflecting-unit optical system and a scanning optical system. The optical system includes a first optical device, a second optical device made of a resin material which has an anamorphic negative refracting power in a deflection scanning direction and a deflection scan perpendicular direction and has a larger refracting power in the deflection scan perpendicular direction than a refracting power in the deflection scanning direction, and a third optical device made of a glass material which has substantially no refracting power in the deflection scanning direction and a positive refracting power in the deflection scan perpendicular direction. An interval of the scanning lines formed on the scanned surface is adjusted by displacement of the second and third optical devices in an optical axis direction of the before-light-deflecting-unit optical system.

Abstract: An optical scanning apparatus has first and second light sources, a deflection scanning device, and first and second scanning optical systems that guide the first and second laser beams deflected for scanning by the deflection scanning device. The first and second scanning optical systems include scanning lenses and a polarization beam splitter arranged in a downstream side of an optical path of the scanning lens, the first scanning optical system including a half-wave plate arranged in the downstream side of the optical path of the scanning lens and in an upstream side of an optical path of the polarization beam splitter, the first laser beam and the second laser beam having different phases by 180 degrees from each other before being incident on the first and second scanning optical systems.

Abstract: An optical scanner, which scans at least one scanned face by a light beam, includes a light source having a plurality of light emitting points, an optical system before a light deflector configured to form a plurality of light beams from the light source, a light deflector configured to deflect the light beams via the optical system before a light deflector and scan the deflected light beams, and a scanning optical system configured to focus on the scanned face the light beams deflected and scanned by a deflection face of the light deflector, the optical system before a light deflector including a first optical element having a negative power at least in a deflecting and scanning vertical direction, a second optical element having a power only in a deflecting and scanning direction and a third optical element having a power only in the deflecting and scanning vertical direction.

Abstract: An image forming apparatus includes an image carrier having a curvature in a first direction; and an exposure head including a first light emitting element that emits a light having a wavelength ?11 and a light having a wavelength ?12, a first optical system that converges each of the light emitted from the first light emitting element onto the image carrier, a second light emitting element, and a second optical system that converges a light emitted from the second light emitting element onto the image carrier, wherein a position at which the first optical system converges each of the light and a position at which the second optical system converges the light are different from each other with respect to the first direction.

Abstract: An optical device including: a laser light emitting portion that emits laser light; a polygon mirror having a reflective surface that reflects the laser light, the polygon mirror being driven to rotate and deflecting the laser light emitted from the laser light emitting portion; a first lens through which the laser light reflected by the polygon mirror is transmitted, the first lens refracting the laser light; a second lens through which the laser light having passed through the first lens is transmitted, the second lens refracting the laser light; and an adjustment unit that adjusts at least one of a length of a first optical path between the polygon mirror and the first lens, and a length of a second optical path between the first lens and the second lens.

Abstract: According to an aspect of the invention, a control method for an exposure shutter of an image forming apparatus includes, opening the shutter only to a slit glass for monochrome when monochrome printing is performed, and opening the shutter to slit glasses for monochrome and color when color printing is performed.

Abstract: The exposure apparatus is provided with: an optical member; and a holding member that holds the optical member. Both end portions of the optical member are held by the holding member with a first adhering unit that is cured by light irradiation for first duration and a second adhering unit that is cured by light irradiation for second duration which is longer than the first duration.

Abstract: A disclosed optical path switching device includes a polarization bistable VCSEL that emits a beam having a rising polarization plane, a laser light source configured to emit a beam having a polarization plane orthogonal to the rising polarization plane, and an optical path switching unit configured to switch an optical path of the beam emitted from the polarization bistable VCSEL by switching the angle of the rising polarization plane of the beam emitted from the polarization bistable VCSEL. The beam emitted from the polarization bistable VCSEL is incident on an entrance window of the optical path switching unit, and the beam emitted from the laser light source is incident on an exit window of the polarization bistable VCSEL.

Abstract: An image-forming device has cylindrical image-carrying members, and an optical scanning unit. The cylindrical image-carrying members are in a main casing for rotating about respective rotational axes which are parallel to one another and juxtaposed in a single direction. The optical scanning unit is in the main casing and has laser generators, a rotatable polygon mirror, mirrors, and lenses. The laser generators have a one-to-one relationship to the image-carrying members to emit laser beams. The rotatable polygon mirror deflects the respective laser beams to scan the respective image-carrying members. The mirrors have a one-to-one relationship to the image-carrying members to guide the respective laser beams along respective optical paths to the respective image-carrying members. The lenses have a one-to-one relationship to the plurality of image-carrying members provided in the respective optical paths and between the respective mirrors and the respective image-carrying members.

Abstract: An image forming apparatus includes an electrostatic latent image carrier, and an optical writing device including at least one light source, at least one aperture, at least one light shield, a light deflector, an image forming lens, and a housing. The aperture adjusts a light beam generated by the light source into a reference shape. The light shield shields an optical path formed between the light source and the aperture by the light beam. The light deflector deflects the light beam to scan in a main scanning direction. The image forming lens focuses the deflected light beam to scan on the surface of the electrostatic latent image carrier to form an electrostatic latent image on the surface of the electrostatic latent image carrier. The housing contains the light source, the light deflector, and the image forming lens. The housing is integrally molded with the aperture and the light shield.

Abstract: Provided is a line head module including line heads on which a plurality of light emission elements are arrayed and exposing a photosensitive body by the light from the light emission elements, including: a support having a rotation axis parallel to the photosensitive body; and the plurality of line heads which are provided on the peripheral surfaces of the support and switched with respect to the photosensitive body by rotating the support about the rotation axis.

Abstract: An f-? lens is joined to a mount through a light curable bond, forms an incident deflected beam onto a photosensitive body, and includes a lens part which has an incident side on which the deflected beam is incident, and an exiting side which is disposed near the photosensitive body and on which the entered deflected beam is exited, an joining part which has a joining side which is extended from the incident face and is joined to the mount, and an emitting side which is extended from the exiting face and disposed to face the joining side, and which a light beam for curing the light curable bond is scanned, and an emitting part which is formed on the emitting side in a non-planar shape and provided to decrease loss of light quantity of the light beam scanned on the emitting face, so that the f-? lens provides an improved joining force in a joining process by a light cure joining type.

Abstract: A light scanning unit includes: a light source generating and irradiating at least one beam corresponding to an image signal; a beam deflector deflecting and scanning the beam irradiated by the light source; and an f-? lens forming an image from the beam deflected by the beam deflector onto a surface to be scanned, the f-? lens being provided as one lens and satisfies the following equation (2): - 0.2 < SAG ? ? 1 + SAG ? ? 2 d 2 < 0.2 ( 2 ) where SAG 1 is Z value of an incident surface of the f-? lens, which faces the beam deflector, SAG 2 is Z value of the exit surface of the f-? lens, which faces the surface to be scanned, based on an XYZ coordinate system in which a main scanning plane is a Y-Z plane and a sub-scanning plane is an X-Z plane, and d2 is a center thickness of the f-? lens.

Abstract: A spindle motor and a spindle motor assembly, and an image forming device having the same. The spindle motor includes a shaft rotatably coupled to a stator, a rotor to rotate with the shaft, and a dynamic pressure generator to generate a dynamic pressure to make the rotor contact toward the stator by an ambient air flow generated during a rotation of the rotor.

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: An optical printer has a DMD as a spatial light modulator. An optical image corresponding to a picture frame is projected from the DMD onto a photographic paper in a variable size to print the picture frame in a designated print size. When a maximum print size is designated, image data stored in three color image memories is entirely converted into mirror drive data for driving all micromirrors of the DMD in accordance with the image data. When a smaller print size is designated, the image data is thinned to reduce the image data size in correspondence with the smaller print size. Also a smaller area of the DMD is selected as an active area in which micromirrors are driven in accordance with the thinned image data, to print a picture in the smaller print size.

Abstract: A refractive body includes a lens, holder, and aperture particularly suited for use in raster scanners. The refractive body advantageously can be made from resinous materials, such as plastics, but can be formed from any refractive material as may be appropriate. The aperture is formed from portions of the refractive body surrounding the lens and can act to divert excess light from the optical path of the scanner by refraction or reflection.

Abstract: Optical systems are disposed in the two symmetrical direction with respect to an optical deflector, and direct the optical beams deflected by the optical deflector into respective surfaces to be scanned, and forming images thereon. A housing encloses a plurality of light sources, optical deflector and optical systems, the housing includes a base plate on which the optical deflector and optical system, and a side wall surrounding the base plate; the base plate divides the housing into two sections; the plurality of light sources are disposed on the side wall; and optical components of the optical systems are distributed into the two sections of the housing.

Abstract: In an image forming apparatus, an object surface (14) is disposed facing one end face of a rod lens array (10), while an image surface (16) is disposed facing the other end face thereof. A lens working distance of the rod lens array on the object side is substantially equal to that on the image side. An actual object-image distance Tco is set between the conjugate length TC1 at which the average value MTFave of the MTF of the rod lens array in the lens array direction is maximized and the conjugate length TC2 at which the &Dgr;MTF(=(MTFmax−MTFmin)/MTFave) is minimized, and a shift quantity &Dgr;TC(=|TCo−TC1|) is set within 0 mm<&Dgr;TC<+02 mm for the conjugate length TC1 at which the MTFave is maximized.

Abstract: The image reproduction system includes a light exposure unit and a photosensitive member having an outer surface. The exposure unit includes a staggered plurality of linear LED arrays and a staggered plurality of discrete objectives associated therewith which focus the light generated by the LED arrays on the outer surface of the photosensitive member.

Abstract: A rod lens array for optical printer head includes a plurality of rod lenses arranged cyclically in a predetermined direction. The rod lenses are fixed by filling a opaque substance into the gaps separating the respective rod lenses and sandwiching the rod lenses and the opaque substance with a pair of side panels. The side panels have a cyclical structure resulting in undulations at least on their surface facing the rod lenses, and the pitch of the beat generated by the cycle or arrangement of the plurality of rod lenses and the cyclical structure of the side panels is not greater that 0.6 mm or substantially infinite.

Abstract: It is an exemplified object of the present invention to provide an optical unit that can easily and inexpensively align an optical axis of the lens and a beam from a light source during continuous operation, and to provide an electrophotographic recording device that has such an optical unit and thereby can form a high-quality latent image on a photosensitive body. The optical unit as an exemplified embodiment of the present invention is configured to have the optical axis of the lens and a mounting position thereof substantially aligned with each other, and thus reduce or eliminate a misalignment of the optical axis with the light source and lens even if temperature rises.

Abstract: The image reproduction system includes a light exposure unit and a photosensitive member having an outer surface. The exposure unit includes a staggered plurality of linear LED arrays and a staggered plurality of discrete objectives associated therewith which focus the light generated by the LED arrays on the outer surface of the photosensitive member.

Abstract: An exposure device in which an image forming lens is disposed in such a posture that the center line of an image forming is out of axial alignment with the center of beam intensity distribution of the light emitting diode output (the center of beam intensity distribution) so as to reduce possible incidence of stray light when local part of the light output from the light emitting diode array reflects on said wires. As a result, the stray light does not strikes the circumference surface of the image supporting body and the vivid image can be formed.

Abstract: Scan line bow correction for raster output scanners, and systems that use raster output scanners. Scan line bow correction is performed in raster output scanners having a post-polygon optical system that includes an f-&thgr; lens system that has at least two multiple scan lenses by controllably tilting a second scan lens along the fast-scan axis. Beneficially, the tiltable scan lens is mounted on a mounting pad that includes a threaded hole. A threaded set screw screws into the threaded hole to provide an adjustable support. In practice the threaded hole-set screw should have a high number of threads per millimeter to provide fine bow correction adjustment.

Abstract: A semiconductor laser array emits a plurality of laser beams. A polygon mirror deflects the plurality of laser beams together. A prism type reflector separates the deflected laser beams to different directions that are generally along an arrangement direction of a plurality of photoreceptors. The separated laser beams are input to the respective photoreceptors through mirrors and cylindrical lenses.

Abstract: An ion generator for the generation of a plasma is assembled from module subassemblies. The first subassembly includes a dielectric plate 1, on the first surface 1a of which are located a large number of first electrodes 3, and the second surface 1b of which is coated with a structured conductive layer 2. The second subassembly includes an aperatured spacer plate with a large number of dielectric spacers with a second electrode 5 on the side facing away from the dielectric plate 1. In joining the subassemblies together, the aperatured spacer plate is connected to the dielectric plate 1 at its first surface 1a in such a way that cavities 6 for accommodating plasma are formed by the first electrodes 3, parts of the first surface 1a of the dielectric plate 1 and the spacers 4 with the second electrodes 5. The first set of electrodes 3 shield the points where the subassemblies are bonded together from plasma in the cavities.

Abstract: A multi-beam scanning optical apparatus of the present invention which is a multi-beam scanning apparatus which forms an image on a scanned surface via a plurality of laser beams, the laser scanning device has, a light source emitting a plurality of laser beams, a modulation device capable of switching the respective modulation frequencies of the laser beams, a deflection device deflecting the laser beams, capable of switching the scanning cycle of the laser beams, an axially symmetric optical system changing the distance among the laser beams on the scanned surface relative to a direction perpendicular to both an optical axis of the laser beams and a scanning direction by inserting itself into the optical path of the laser beams and a moving device inserting said axially symmetric optical system into the optical path.