Abstract: An imaging system having reduced susceptibility to thermally-induced stress birefringence comprising relay optics and projection optics. One of either the relay optics or the projection optics is a reflective optical system that includes reflective optical elements, and the other is a refractive optical system having a negligible or low susceptibility to thermal stress birefringence. The refractive optical system includes: a first group of refractive lens elements located upstream from an aperture stop, and a second group of refractive lens elements located downstream from the aperture stop. The refractive lens elements in the first and second groups that are immediately adjacent to the aperture stop are fabricated using optical materials having a negligible susceptibility to thermal stress birefringence, and the other refractive lens elements in the first and second groups are fabricated using optical materials having at most a moderate susceptibility to thermal stress birefringence.

Abstract: A projector includes: a light source that emits light; a first lens array that divides the light emitted from the light source into a plurality of partial light beams; a second lens array that focuses the plurality of partial light beams emitted from the first lens array; condenser lenses that superimpose the plurality of partial light beams emitted from the second lens array on target illumination regions; and liquid crystal panels that modulate the light beams passing through the condenser lenses according to image information, wherein each of the condenser lenses is a single lens that achieves telecentric illumination when superimposing the partial light beams, and only the condenser lenses are arranged as lenses between the second lens array and the liquid crystal panels.

Abstract: A projecting lens for projecting a light of an image generating device onto a screen is provided. The image generating device has a light valve. The projecting lens includes a first lens group and a second lens group. The first lens group has an imaging optical axis and a first effective refractive power. The second lens group has a second effective refractive power, and is disposed between the first lens group and the light valve. The light projected from the light valve to the second lens group generates an intermediate image, which is focused on the screen via the first lens group to form an image. A center of the image and a center of the light valve are located on the same side of the optical axis, and a center of the intermediate image is located on the other side of the optical axis.

Abstract: While one beam is being branched into a plurality of beams with different optical path lengths, the beams can be converged on the same position in the optical-axis direction with a simple structure even when relative angles between the beams differ. Provided is a beam splitter apparatus including a beam splitter that branches an input pulsed beam into two optical paths with different optical path lengths; relay optical systems that are disposed in the respective branching optical paths and that relay pupils in the optical paths; a beam splitter that multiplexes the relayed pulsed beams in the two optical paths; and a reflection optical system that endows pulsed beams branching off via the beam splitter with a relative angle.

Abstract: The observation device includes a micro optical system and a macro optical system. The observation device is configured in such a way that the micro and macro optical systems share an image position and that the first pupil position of the micro optical system and the second pupil position of the macro optical system substantially coincide with one another.

Abstract: An imaging system having reduced susceptibility to thermally induced stress birefringence, comprising; a relay lens, which images the object plane onto an intermediate image plane; a projection lens, which images the intermediate image plane onto the display surface. The lens elements that are immediately adjacent to a relay lens aperture stop and a projection lens aperture stop are fabricated using glasses having a negligible susceptibility to thermal stress birefringence, and the other lens elements are fabricated using glasses having at most a moderate susceptibility to thermal stress birefringence as characterized by the thermal stress birefringence metric.

Abstract: An object of the present invention is to provide an optical multiplexing apparatus and a projector that keep an optical system small, and easily adjust a number of light source units. The optical multiplexing apparatus has: a light source section that uses light source units to emit collimated beams; a first lens portion that converges the collimated beams which enter at different incident angles from each other to define converging positions; and a second lens portion that has focal points that correspond to the converging positions, respectively, wherein the first and second lens portions form an optical reduction system, and an optical axis of the second lens portion, which is directed to the corresponding focal point to one of the converging positions, extends along anther optical axis of the second lens position, which is directed to the corresponding focal point to another of the converging positions.

Abstract: Provided is a magnified-projection optical system, which can retain a considerably long back focus although a focal length is short and which has a small chromatic aberration. The optical system comprises a projecting optical system, a relay optical system and a display element, which are sequentially arrayed from a screen side along the optical axis. The projecting optical system enlarges and projects the image, which has been linearly focused by the relay optical system, on the screen, and includes a negative group and a positive group arrayed sequentially from the screen side and having a negative optical power and a positive optical power, respectively. The optical system satisfies the following conditional relations of |Fb/F|>10 and 0.5<|F/Fp|<2.

Abstract: An image display device for optically displaying an image is disclosed. This device includes: a light source; an imaging-light generator converting light emitted from the light source, into imaging light representative of the image to be displayed, to thereby generate the imaging light; a relay optical system focusing the imaging light emitted from the imaging-light generator, on an image plane which is located at an optically conjugate position to the imaging-light generator, the relay optical system defining a pupil through which the imaging light passes, within the relay optical system; a variable-focus lens disposed at a position generally coincident with the pupil, the variable-focus lens having a varying focal length; and a wavefront-curvature adjuster configured to vary the focal length by operating the variable-focus lens, to thereby adjust a wavefront curvature of the imaging light emitted from the relay optical system.

Abstract: Wide-angle, deep-field, close-focusing optical systems are disclosed. According to one aspect, the optical system comprises a negative lens unit and a relay lens. The negative lens unit accepts radiation from an object in space. The relay lens is coupled to the negative lens unit. The negative lens unit and the relay lens are aligned on an optical axis in that order. The negative lens unit forms a first image on the relay lens to form a final image at a final image plane at a distance from the relay lens. The relay lens may comprise a zoom lens or zoom lens components, which may be movable.

Abstract: There is provided a lighting system having a high spatial resolution appropriate to a high-frequency component by evanescent waves in a negative refraction lens. The lighting system includes a light emitter thin film (106) which includes a light emitting material which emits light when an energy is applied, a cathode (101) for applying an electron beam (102) which is the energy, to the light emitter thin film (106), and a negative refraction lens (110) which is formed of a material exhibiting negative refraction, and has an optical system for projecting light emitted from the light emitter thin film (106), on an object.

Abstract: An optical system includes a lens, a pupil relay, and an aperture stop positioned at a focal point of the lens between the lens and the pupil relay. The lens is configured to collect a plurality of light bundles. Each light bundle emanates from a field point of an object plane and has a center ray substantially parallel to an optical axis of the lens. The lens is configured to direct the center ray of each light bundle through the aperture stop and onto the pupil relay. The pupil relay is configured to image a plane of the aperture stop onto a sensor array.

Abstract: The wide angle lens system described herein allows projection devices (e.g., rear projection display devices) to be more compact than would otherwise be possible. The lens system includes a wide angle lens stage and a relay lens stage. When operating as a projection device, the relay lens stage projects a distorted intermediate image to the wide angle lens stage, which projects the image for display. The distortion cause by the relay lens stage compensates (i.e., is approximately equal and opposite) for the distortion caused by the wide angle stage. The distortion can be the image shape and/or the focal plane. When operating as a taking device, the wide angle stage provides a distorted image to the relay lens stage, which compensates for the distortion and provide a less distorted, or even non-distorted image, for capture.

Abstract: Provided is an endoscope optical system including first deflecting means that deflects light incident along an incident optical axis in a direction along a first axis perpendicular to the incident optical axis and emits the light; second deflecting means having two reflecting faces that fold back the light emitted from the first deflecting means along a second axis separated from the first axis by a gap; and third deflecting means that deflects the light folded back by the second deflecting means in a direction perpendicular to the first axis and along a plane including the incident optical axis, wherein the first deflecting means is provided so as to be capable of swiveling about the first axis relative to the second deflecting means, and the two reflecting faces of the second deflecting means are disposed to form an obtuse angle therebetween.

Abstract: An imaging system having reduced susceptibility to thermally induced stress birefringence, comprising; a relay lens, which images the object plane onto an intermediate image plane; a projection lens, which images the intermediate image plane onto the display surface. The lens elements that are immediately adjacent to a relay lens aperture stop and a projection lens aperture stop are fabricated using glasses having a negligible susceptibility to thermal stress birefringence, and the other lens elements are fabricated using glasses having at most a moderate susceptibility to thermal stress birefringence as characterized by the thermal stress birefringence metric.

Abstract: A fixed-focus lens adapted to be disposed between a primary image side and a second image side is provided. The fixed-focus lens includes a second lens group, a first lens group, and a curved reflector arranged in sequence from the primary image side to the second image side. The second lens group includes a first lens, a second lens, and a third lens arranged in sequence from the primary image side to the second image side. The first lens and the third lens have positive refractive powers and each of the first lens, the second lens, and the third lens is a spherical lens.

Abstract: An endoscope has a tubular shaft whose interior contains components, in particular lenses, spacers, diaphragms, prisms and filters of an optical system, said components being at least partially surrounded by a support piece made of shrunk material. It is proposed that the components be surrounded by a transparent and tube-sleeve-shaped shrunk material which has been shrunk before the components are introduced into the tubular shaft.

Abstract: Wide-angle, deep-field, close-focusing optical systems are disclosed. According to one aspect, the optical system comprises a negative lens unit and a relay lens. The negative lens unit accepts radiation from an object in space. The relay lens is coupled to the negative lens unit. The negative lens unit and the relay lens are aligned on an optical axis in that order. The negative lens units forms a first image on the relay lens to form a final image at a final image plane at a distance from the relay lens. The relay lens may comprise a zoom lens or zoom lens components, which may be movable.

Abstract: Provided is an endoscope optical system including first deflecting means that deflects light incident along an incident optical axis in a direction along a first axis perpendicular to the incident optical axis and emits the light; second deflecting means having two reflecting faces that fold back the light emitted from the first deflecting means along a second axis separated from the first axis by a gap; and third deflecting means that deflects the light folded back by the second deflecting means in a direction perpendicular to the first axis and along a plane including the incident optical axis, wherein the first deflecting means is provided so as to be capable of swiveling about the first axis relative to the second deflecting means, and the two reflecting faces of the second deflecting means are disposed to form an obtuse angle therebetween.

Abstract: A scanning optical device that scans a light beam through a relay optical system, the relay optical system comprising: front group lenses arranged at a light source side; rear group lenses arranged at a side of a surface to be scanned; and first and second minors arranged between the front group lenses and the rear group lenses and supported by a common supporting member, wherein a normal vector of a minor surface of the first minor makes an angle (180??) with an incident optical axis from the front group lenses, a normal vector of the second minor makes an angle ? (??180×m) with the normal vector of the first minor, and the supporting member includes a mechanism being linearly movable in a direction which makes an angle (???+90) with the normal vector of the first mirror.

Abstract: Light field imaging systems, and in particular light field lenses that can be mated with a variety of conventional cameras (e.g., digital or photographic/film, image and video/movie cameras) to create light field imaging systems. Light field data collected by these light field imaging systems can then be used to produce 2D images, right eye/left eye 3D images, to refocus foreground images and/or background images together or separately (depth of field adjustments), and to move the camera angle, as well as to render and manipulate images using a computer graphics rendering engine and compositing tools.

Abstract: Disclosed are a system and method for microprojection that uses multiple imagers to produce a high resolution output image. Each of a set of imagers produces a portion of the final image. Relay lenses then tile the individual image portions together into a combined image. Because the height of the individual imagers is smaller than the height of a monolithic imager, they can fit into a very thin device. The combined image has a resolution equal to the sum of the resolutions of the individual imagers. The individual images are tiled together within the microprojector itself rather than on a projection screen. This allows the tiling to be adjusted once at the factory and set forever. In some embodiments, the light created for use by the microprojector is split by a polarizing beamsplitter. Each resultant polarized beam is then sent to an imager. Another polarizing beamsplitter combines the individual images.

Abstract: A variable power relay optical system comprising: a variable power lens performing zooming a secondary image based on light from a primary image; and a rear group forming the secondary image based on the light passing through the variable power lens; the variable power lens consisting of, in order from the primary image side, a first group having positive power, a second group having negative power, a third group having positive power, and a fourth group having positive power, upon zooming from a high magnification end to a low magnification end, the fourth group being moved to the secondary image side, and a distance between the first group and the second group increasing, positions of the primary image and the secondary image, an entrance pupil of the variable power relay optical system, a pupil of the variable power lens, and an exit pupil of the variable power relay optical system being substantially kept constant, and the pupil of the variable power lens being disposed to the secondary image side of the

Abstract: An optical system (light guiding optical system) for guiding G-light and R-light to liquid crystal panels is protruded in an opposite direction from projection optical system with regard to an optical axis of a light source. A space is created between an optical engine and a wall surface, and air stream for suction fan is thus secured. A distance (H1) between the optical engine and the wall surface can be reduced to, for example, a thickness of an external housing of the projector. Since a unit comprising the light source and a suction fan is retracted in a direction of the projection optical system than a protruded portion of the light guiding optical system, a distance (H2) from an end edge of the optical engine to a projection light emitting position can be reduced.

Abstract: System and method for utilizing two prisms spatially separated is provided. The two prisms spatially separated allows the two prisms typically found in a TIR optical relay system to be spatially separated. In an embodiment, one or more optical relay lenses are interposed between the two prisms. The prism positioned on the object side may be integrated into one or more of the optical relay lenses, thereby further simplifying the optical relay design. In another embodiment, the one or more optical relay lenses may have an optical axis that is offset from the optical axis of incoming light to cause a pupil shift. An aspherical lens may be included to correct for the pupil shift and create a more uniform illumination image.

Abstract: An infinity-conjugate lens relay with a moving first lens is used to select a plane of interest from an image volume. This plane can be selected so that the image is corrected for spherical aberration due to non-ideal imaging conditions. This effectively will allow for deeper, corrected imaging for high power microscopes. Using an infinity-conjugate relay, this device has an ideal “bypass” mode for regular imaging without correction. The device also utilizes software that automatically controls the device for correcting live images.

Abstract: Provided is a magnified-projection optical system, which can retain a considerably long back focus although a focal length is short and which has a small chromatic aberration. The optical system comprises a projecting optical system, a relay optical system and a display element, which are sequentially arrayed from a screen side along the optical axis. The projecting optical system enlarges and projects the image, which has been linearly focused by the relay optical system, on the screen, and includes a negative group and a positive group arrayed sequentially from the screen side and having a negative optical power and a positive optical power, respectively. The optical system satisfies the following conditional relations of |Fb/F|>10 and 0.5<|F/Fp|<2.

Abstract: An imaging system. An array of light sources and an array of lenses corresponding to the light sources and having optical axes substantially parallel to one another are provided. The lenses produce collimated output beams. An afocal optical relay having an optical axis substantially parallel to the optical axes of the lenses is also included, the array of lenses being positioned relative to the afocal optical relay so as to form an optical system that produces an image of each collimated output beam on an image plane, each image having a prescribed depth of focus and spot size. The light sources preferably are lasers producing an array of respective laser beams having high intensity and a long waist. A system for writing information on a light-sensitive label includes the imaging system. Methods of imaging and of writing information on a light-sensitive label are also provided.

Abstract: The exposure time for obtaining a bright image in an image-acquisition optical system can be reduced, and shifting of an image visually observed in an observation optical system is prevented, thus enabling stable observation. A microscope including an image-acquisition optical path for recording an image focused by an objective lens and an observation optical path for visually observing an image split-off from the image-acquisition optical path; and including an aperture stop, in the observation optical path, for stopping down the numerical aperture thereof to smaller than the numerical aperture of the image-acquisition optical path.

Abstract: An external optical relay assembly to allow an infrared camera with a fixed aperture to be used with a variety of fore optics, including refractive compound lenses, reflective telescopes, and reflective/refractive lenses, by providing an external, cooled aperture, that can be adjusted to provide effective f-number matching to the fore optic, allowing any f-number fore optic to be used with the infrared camera. This allows users of large families of similar telescopes, for example, to use their inventory of infrared Ritchie-Chrétien telescopes with a single infrared camera, regardless of f-numbers.

Abstract: System and method for utilizing two prisms spatially separated is provided. The two prisms spatially separated allows the two prisms typically found in a TIR optical relay system to be spatially separated. In an embodiment, one or more optical relay lenses are interposed between the two prisms. The prism positioned on the object side may be integrated into one or more of the optical relay lenses, thereby further simplifying the optical relay design. In another embodiment, the one or more optical relay lenses may have an optical axis that is offset from the optical axis of incoming light to cause a pupil shift. An aspherical lens may be included to correct for the pupil shift and create a more uniform illumination image.

Abstract: A projecting lens for projecting a light of an image generating device onto a screen is provided. The image generating device has a light valve. The projecting lens includes a first lens group and a second lens group. The first lens group has an imaging optical axis and a first effective refractive power. The second lens group has a second effective refractive power, and is disposed between the first lens group and the light valve. The light projected from the light valve to the second lens group generates an intermediate image, which is focused on the screen via the first lens group to form an image. A center of the image and a center of the light valve are located on the same side of the optical axis, and a center of the intermediate image is located on the other side of the optical axis.

Abstract: An objective having a plurality of optical elements arranged to image a pattern from an object field in an object surface of the objective to an image field in an image surface region of the objective at an image-side numerical aperture NA>0.8 with electromagnetic radiation from a wavelength band around a wavelength ?, includes a number N of dioptric optical elements, each dioptric optical element i made from a transparent material having a normalized optical dispersion ?ni=ni(?0)?ni(?0+1 pm) for a wavelength variation of 1 pm from a wavelength ?0. The objective satisfies the relation ? ? i = 1 N ? ? ? ? n i ? ( s i - d i ) ? ? 0 ? NA 4 ? A for any ray of an axial ray bundle originating from a field point on an optical axis in the object field, where si is a geometrical path length of a ray in an ith dioptric optical element having axial thickness di and the sum extends on all dioptric optical elements of the objective. Where A=0.

Abstract: The invention provides a rigid endoscope relay optical system that can be fabricated at lower costs while its brightness is kept intact by reducing parts count. The rigid endoscope optical system has an elongate insert and is adapted to implement image transfer using relay lenses Re1 to Re7. The relay lenses Re1 to Re7 each have at least two rod lenses and satisfy nd>2, where nd stands for the refractive index on d-line basis of each rod lens in the relay lens.

Abstract: An object is to provide a projection optical system, for example, capable of improving the throughput of scanning exposure in application to scanning exposure apparatus. A projection optical system for forming an image of a first surface and an image of a second surface on a third surface comprises a first imaging optical system, a second imaging optical system, a third imaging optical system, a fourth imaging optical system, a fifth imaging optical system, a sixth imaging optical system, a seventh imaging optical system, a first folding member disposed between the third imaging optical system and the seventh imaging optical system, and a second folding member disposed between the sixth imaging optical system and the seventh imaging optical system.

Abstract: The invention provides a rigid endoscope relay optical system that can be fabricated at lower costs while its brightness is kept intact by reducing parts count. The rigid endoscope optical system has an elongate insert and is adapted to implement image transfer using relay lenses Re1 to Re7. The relay lenses Re1 to Re7 each have at least two rod lenses and satisfy nd>2, where nd stands for the refractive index on d-line basis of each rod lens in the relay lens.

Abstract: An objective having a plurality of optical elements arranged to image a pattern from an object field in an object surface of the objective to an image field in an image surface region of the objective at an image-side numerical aperture NA>0.8 with electromagnetic radiation from a wavelength band around a wavelength ?, includes a number N of dioptric optical elements, each dioptric optical element i made from a transparent material having a normalized optical dispersion ?ni=ni(?0)?ni(?0+1 pm) for a wavelength variation of 1 pm from a wavelength ?0. The objective satisfies the relation ? ? i = 1 N ? ? ? ? n i ? ( s i - d i ) ? ? 0 ? NA 4 ? A for any ray of an axial ray bundle originating from a field point on an optical axis in the object field, where si is a geometrical path length of a ray in an ith dioptric optical element having axial thickness di and the sum extends on all dioptric optical elements of the objective. Where A=0.

Abstract: A system and method for spectral filtering of images are provided. The system and method utilize a first biconic lens surface to astigmatize a substantially 2-D system pupil into a substantially 1-D pupil (e.g., slit-shaped), and a second biconic lens surface to restore the astigmatic pupil to good quality. Advantageously, the light stream may be filtered with a variable filter.

Abstract: The wide angle lens system described herein allows projection devices (e.g., rear projection display devices) to be more compact than would otherwise be possible. The lens system includes a wide angle lens stage and a relay lens stage. When operating as a projection device, the relay lens stage projects a distorted intermediate image to the wide angle lens stage, which projects the image for display. The distortion cause by the relay lens stage compensates (i.e., is approximately equal and opposite) for the distortion caused by the wide angle stage. The distortion can be the image shape and/or the focal plane. When operating as a taking device, the wide angle stage provides a distorted image to the relay lens stage, which compensates for the distortion and provide a less distorted, or even non-distorted image, for capture.

Abstract: The invention discloses a projecting system. The projecting system includes two sets of lens. The first set of lens has a first focal length for focusing an incident ray of light to form a first image. The second set of lens has a second focal length for projecting the first image to form a second image. The two sets of lens are separated by a lens-apex distance relative to the light path between the two sets of lens. The second focal length is smaller than or equal to the lens-apex distance. A difference between the second focal length and the lens-apex distance is smaller than or equal to a half of the first focal length.

Abstract: The invention relates to an image transmission system for rigid endoscopes, having a central rod lens and two outer rod lenses, which are symmetrical in respect to one another in relation to a vertical central plane of the image transmission system relative to the optical axis, wherein all lens elements consist of optically homogenous material, all optically active surface are spherical and two lens elements are stuck to on another facing each other or facing away from one another on the opposite sided of the central and outer lenses in the main lens elements of the rod lenses so that the resulting composite lens is biconvex. According to the invention, the rod lenses are arranged apex to apex next to one another and the central rod lens is substantially as long as or longer than the outer rod lenses.

Abstract: The application relates to an ergonomic tube for a microscope. A binocular head is provided on the tube. A deflection element is provided in the tube and a deflection mirror is assigned to the element, the mirror being located behind the optical path of the lens, when viewed from the user's position. A single tube-lens system is positioned in the optical path of the tube. A modification to the inclination of the oclar optical path in relation to the horizontal (H) by a value ?causes the position of the deflection mirror to be modified by an angle ?/2.

Abstract: Wide-angle, deep-field, close-focusing optical systems are disclosed. According to one aspect, the optical system comprises a negative lens unit and a relay lens. The negative lens unit accepts radiation from an object in space. The relay lens is coupled to the negative lens unit. The negative lens unit and the relay lens are aligned on an optical axis in that order. The negative lens units forms a first image on the relay lens to form a final image at a final image plane at a distance from the relay lens. The relay lens may comprise a zoom lens or zoom lens components, which may be movable.

Abstract: A refractive projection optical system in which a large image side numerical aperture can be ensured by interposing liquid in the optical path to the image plane, and an image having good planarity can be formed while suppressing radial upsizing. The projection optical system comprising a first image forming system arranged in the optical path between a first plane (R) and a point optically conjugate to a point on the optical axis of the first plane, and a second image forming system arranged in the optical path between the conjugate point and a second plane. In the projection optical system, all optical elements having power are refractive optical elements. The optical path between the projection optical system and the second plane is fillable with liquid having a refractive index larger than 1.3.

Abstract: The wide angle lens system described herein allows projection devices (e.g., rear projection display devices) to be more compact than would otherwise be possible. The lens system includes a wide angle lens stage and a relay lens stage. When operating as a projection device, the relay lens stage projects a distorted intermediate image to the wide angle lens stage, which projects the image for display. The distortion cause by the relay lens stage compensates (i.e., is approximately equal and opposite) for the distortion caused by the wide angle stage. The distortion can be the image shape and/or the focal plane. When operating as a taking device, the wide angle stage provides a distorted image to the relay lens stage, which compensates for the distortion and provide a less distorted, or even non-distorted image, for capture.

Abstract: An endoscope has a tubular shaft whose interior contains components, in particular lenses, spacers, diaphragms, prisms and filters of an optical system, said components being at least partially surrounded by a support piece made of shrunk material. It is proposed that the components be surrounded by a transparent and tube-sleeve-shaped shrunk material which has been shrunk before the components are introduced into the tubular shaft.

Abstract: An imaging optical system includes a subtelescope array, with at least two subtelescopes, each having a single entrance pupil and an exit light beam. Each subtelescope has an optical pointing axis, and the pointing axes for the subtelescopes are parallel. An imager forms an image from the exit light beams at an image surface, where there is a sensor such as a focal plane array. Preferably, a phase shifter array includes a phase shifter for each of the subtelescopes. The phase shifter array receives the exit light beam of each of the subtelescopes and has a capability to adjust the phase of at least one of the exit light beams. The imager receives the phase-shifted exit light beams.

Abstract: A relay set (4, 4?) for the optical system of a rigid endoscope, the optical system including an objective (1) at the distal end, an ocular (5) at the proximal end and between them a relay lens system consisting of several relay sets (2, 3, 4), the relay set (4, 4?) consisting of two half sets (4.1, 4.2) having the same lens units (11.1, 12.1, 13.1; 11.2, 12.2 13.2) arranged symmetrically with respect to the center (10) of the set (4, 4?), each half set (4.1, 4.2) consisting of two positive power lens units (11.1, 13.1; 11.2, 13.2) at the ends and one negative power lens unit (12.1; 12.2) in the middle, is characterized in that each half set is of Triplet design.

Abstract: An optical system for viewing an object has a plurality of lenses and a main optical axis coincident with the centers of the lenses. The optical system further comprises a low magnification optical subsystem that is operative to view the object at a first magnification and a high magnification optical subsystem that is operative to view the object at a second magnification that is higher than the first magnification. The high magnification optical subsystem has a high magnification optical axis along which light rays that are received from the main optical axis are transmitted. A movable element is locatable on the high magnification optical axis and is movable in directions transverse to the axis for receiving and transmitting light rays.

Abstract: An endoscope objective lens is provided and has a front-group divergent lens system, an aperture stop, and a rear-group convergent lens system in this order from the object side. The back focal length Bf of the whole system is longer than 2.5 times the combined focal length f of the whole system. The rear-group convergent lens system includes a cemented lens. The endoscope objective lens satisfies the specific formula.