Abstract: A reflective optical system includes, in traveling order of light, a correction plate having an aspherical surface and a reflecting mirror for concentrating the light. An image is formed out of an optical path between the correction plate and the reflecting mirror.

Abstract: An imaging system includes a compound elliptical concentrator having an illumination source at an entry aperture and having an exit aperture directed to project light onto the surface of an object. The compound elliptical concentrator includes first and second reflective surfaces that are arcs of different ellipses. The ellipse that defines the arc of the first reflective surface has one focus that is proximate to an entry end of the second reflective surface. The ellipse that defines the arc of the second reflective surface has a focus that is proximate to the entry end of the first reflective surface. The other foci of the ellipses are at or beyond the exit aperture of the compound elliptical concentrator and are preferably symmetrically aligned with respect to the surface to be imaged. The reflective surfaces are on the opposite sides of a plane of symmetry and are configured such that multiple reflections of extreme rays from the illumination source are deterred.

Abstract: A catadioptric projection optical system is provided, which can use a beam splitting optical system smaller in size than a conventional polarizing beam splitter, can set a long optical path from a concave reflecting mirror to an image plane, allows easy adjustment of the optical system, and has excellent imaging performance. A light beam from an object surface forms a first intermediate image through a refracting lens group. A light beam from the first intermediate image passes through a polarizing beam splitter and is reflected by a concave reflecting mirror to form a second intermediate image in the polarizing beam splitter. A light beam from the second intermediate image is reflected by the polarizing beam splitter means to form a final image on the image plane via a refracting lens group. The polarizing beam splitter means is arranged near the positions at which the intermediate images are formed.

Abstract: A catadioptric reduction projection optical system having a first lens unit having negative refractive power and widening a light beam from a reticle, a prism type beam splitter for transmitting therethrough a light beam from the first lens unit, a concave reflecting mirror for returning the light beam emerging from the beam splitter to the beam splitter while converging it, and a second lens unit having positive refractive power and converging the light beam returned to the beam splitter and reflected by the beam splitter, and forming the reduced image of a pattern on the reticle on a wafer.

Abstract: Catadioptric systems are provided, comprising a first imaging system, a plane mirror, and a second imaging system. The first imaging system comprises a single-pass optical system and a double-pass optical system that further comprises a concave mirror and a double-pass lens group. The second imaging system comprises a plane mirror and an aperture. The first imaging system forms an intermediate image of an object; the second imaging system re-images the intermediate image on a substrate. The catadioptric systems satisfy various conditions.

Abstract: An improved eyepiece for an optical system. In general, the inventive eyepiece (10) includes a refractive element (16) and an optical arrangement for relaying the entrance pupil of the system to the refractive element. In a specific implementation, the optical arrangement includes a concave primary mirror (12) and a secondary mirror (14). The mirrors are mounted to communicate an image from the refractive element (16) to the entrance pupil (40). In the specific implementation, the refractive element (16) is one or more refractive lenses. The use of a reflective optical arrangement allows for the long eye relief. The placement of the entrance pupil close to the pupil of the lens allows for the use of a compact optical arrangement with high ratio of eye relief to effective focal length with a compact optical arrangement. The system affords minimal lateral chromatic aberration and good image quality.

Abstract: Catadioptric systems are disclosed that project a demagnified image of an object on a substrate. A first optical system substantially collimates a light flux from the object and directs the light flux to a beamsplitter provided with a reflecting surface. A second optical system comprising a concave mirror and a negative lens and having unit magnification receives the light flux from the beamsplitter and directs the light flux back to the beamsplitter. A third optical system then receives the light flux from the beamsplitter and forms an image of the object on the substrate. The catadioptric systems satisfy various conditions.

Abstract: Catadioptric projection systems are disclosed for projecting an illuminated region of a reticle onto a corresponding region on a substrate. The systems are preferably used with ultraviolet light sources (e.g., 193 nm). The systems comprise a first imaging system, a concave mirror, and a second imaging system. The first imaging system comprises a single-pass lens group and a double-pass lens group. The single-pass lens group comprises a first negative subgroup, a positive subgroup, and a second negative subgroup. Light from the illuminated region of the reticle passes through the single-pass lens group and the double-pass lens group, and reflects from the concave mirror to pass back through the double-pass lens group to form an intermediate image of the illuminated region of the reticle. The light is then directed to the second imaging system that re-images the illuminated region of the reticle on the substrate.

Abstract: A projection exposure apparatus achieves good imaging performance as securing a sufficient working distance. This projection exposure apparatus has a projection optical system for projection-transferring a real-size image of a first object onto a second object, which is disposed between the first object and the second object. This projection optical system has a cemented lens consisting of a plano-convex lens and a first negative meniscus lens, a second negative meniscus lens, and path-bending prisms for guiding light from the first object to the plano-convex lens and for guiding light from the concave mirror to the second object. The present invention is based on finding of appropriate ranges of refractive powers of the first and second negative meniscus lenses and appropriate ranges of Abbe numbers of glass materials for the first and second negative meniscus lenses.

Abstract: A FLIR staring array detector system for imaging an object scene using catadioptric optics has a cold shield efficiency approaching unity. The system provides a full format image of the object scene. The catadioptric optics include reflective objective optics for providing an intermediate image of the object scene and refractive relay optics for providing the full format image. The system further includes a staring detector for receiving the full format image.

Abstract: Catadioptric optical systems are disclosed that comprise, objectwise to imagewise, a positive first lens, a meniscus second lens having a convex face oriented objectwise, a meniscus third lens having a concave face oriented objectwise, and a concave spherical mirror having a concave face oriented objectwise. Light from an object passes through the first through third lenses and reflects from the concave mirror to form an image between the third lens and the concave mirror. The system satisfies the condition .vertline.f.sub.123 .vertline./f>10, where f.sub.123 is the aggregate focal length of the first through third lenses, and f is an overall focal length of the system. The first and second lenses are preferably made of a specified optical material, collectively have a positive refractive power, and fulfill the condition .vertline.f.sub.12 .vertline./.vertline.f'.sub.12 .vertline.>1, where f.sub.12 is the aggregate focal length of the first and second lenses, and f'.sub.

Abstract: A projection-type display apparatus including an elliptical condenser mirror having a concave reflecting surface consisting of part of a substantially elliptical surface, a light source arranged near a first focal point of the elliptical surface, a collimator lens having a focal point near a second focal point of the elliptical surface, an optical modulation element array having a lens array on the collimator lens side, in which optical modulation elements each having an area S are two-dimensionally arranged, and a projection lens, wherein the following relations are satisfied: ##EQU1## (when said light source is arranged perpendicular to the elliptical condenser mirror) ##EQU2## (when said light source is arranged parallel to the elliptical condenser mirror).mu.=(B/A).sup.2(A: major axis, B: minor axis)where L is the length of a light-emitting portion of the light source, .mu.

Abstract: Catadioptric systems are disclosed for projecting images of an object such as a mask onto a substrate. The catadioptric systems have high numerical apertures and large working distances. The catadioptric systems are useful with short-wavelength illumination and permit the object and substrate to be in parallel planes. Conditional expressions are provided for the catadioptric systems.

Abstract: A head-mounted image display apparatus (HMD) including an ocular optical system, which has an F-number of 1.5 to 3 and enables a flat and clear image to be observed at a view angle of up to 60.degree. or more with substantially no aberration. The HMD has at least two, surfaces and each having a concave surface directed toward the pupil. The two surfaces are disposed so that light rays from an image display device are reflected by the first surface, and the reflected light rays are reflected by the second surface and pass through the first surface to enter an observer's eyeball.

Abstract: An image display apparatus, e.g. a head-mounted image display apparatus, which enables observation of a clear image at a wide field angle, and which is extremely small in size and light in weight and hence unlikely to cause the observer to be readily fatigued. The image display apparatus has an image display device (6) and an ocular optical system (7). The ocular optical system (7) has a first surface (3), a second surface (4) and a third surface (5), which are disposed in the mentioned order from the observer's eyeball (1) side. The space between the first and second surfaces (3 and 4) and the space between the second and third surfaces (4 and 5) are filled with a medium having a refractive index larger than 1. The first and second surfaces (3 and 4) have different curvatures. The second surface (4) is a reflecting or semitransparent surface which is decentered with respect to an observer's visual axis (2), and which has a concave surface directed toward the observer's eyeball (1).

Abstract: A catadioptric imaging system for an interferometer includes a beamsplitter plate for reflecting a beam of light to a concave mirror for transmitting reflected light from the mirror. The beamsplitter reflections and transmissions produce opposite sign spherical aberrations. A refractive optic is located between the beamsplitter plate and a convex test surface for removing residual spherical aberrations and for permitting more variability in the positioning of the beamsplitter plate. Design variables for both the refractive optic and the position of the beamsplitter plate can be used to adjust a numerical aperture of the beam approaching the test surface. The refractive optic can also be used as a Fizeau objective to further reduce errors in the imaging system.

Abstract: A catadioptric one-to-one optical relay system which is telecentric in both object and image space. The system includes three modules, which include a spherical primary mirror, a spherical secondary mirror with a zero power doublet for axial color correction, and an X-prism for spectral division. The chromatic aberration generated by the X-prism is compensated by the zero power doublet corrector. Because the system is telecentric in both object and image space, the coatings associated with the X-prism are simplified. The system can be used in telescopes, optical systems with sensor protection, and color CCD assemblies.

Abstract: A catadioptric reduction objective has a concave mirror 19', a beam splitter 150' and several lens groups (100', 200'; 300', 400'). The system diaphragm 40' is mounted between beam splitter surface 15' and image plane 36' and especially within the last lens group 400'. NA=0.7; for UV, DUV; image side or both sides telecentric; also achromatized.

Abstract: Magnification correction for small field scanning of large blanks is provided by adding magnification adjusting elements (lenses) to a double pass Wynne-Dyson lens or other type of one-to-one projection lens. The magnification adjusting optical elements includes two pairs of low power lenses, one associated with each of the input and output prisms of a Wynne-Dyson lens. Movement of the magnification adjusting optics provides positive or negative magnification as needed to correct for any expansion or compaction of the blank relative to the reticle (mask) and hence maintain alignment. Further magnification correction is provided by a small velocity relative movement between the reticle and the blank by means of a secondary stage in the scan direction. This corrects for any alignment error in the scan direction and may be used independently of the optical correction technique with any type of projection lens.

Abstract: There is provided an objective lens for focusing a subject light to form a real image on a predetermined focal plane, an eyepiece through which the real image is observed, and the first and second prism assemblies between the objective lens and the eyepiece for erecting an inverted image. The first and second prism assemblies are arranged at a predetermined distance away from each other such that the exit surface of the first prism assembly and the incident surface of the second prism assembly face each other across the focal plane. As a result, the dust on the whole surface of the prism assemblies and the like are made inconspicuous. Moreover, a visual field frame is provided on the focal plane, so that the visual field frame can be prevented from becoming out of focus and the border of the visual field can be seen clearly. Furthermore, a virtual image of a mark such as a target mark is formed in the Albada method.

Abstract: A catadioptric reduction projection optical system having a first lens unit having negative refractive power and widening a light beam from a reticle, a prism type beam splitter for transmitting therethrough a light beam from the first lens unit, a concave reflecting mirror for returning the light beam emerging from the beam splitter to the beam splitter while converging it, and a second lens unit having positive refractive power and converging the light beam returned to the beam splitter and reflected by the beam splitter, and forming the reduced image of a pattern on the reticle on a wafer.

Abstract: A multi-color optical display system (10) employs a multi-powered reflective combiner (20) that together with a monochromatic or partly color-corrected relay lens (16) longitudinally corrects a multi-colored image. The combiner typically includes two surfaces (82, 90) of different optical powers with a reflective coating (106, 108) on each of the surfaces. The coatings are chosen to each reflect a specific wavelength range of colored light used in the system and to transmit all other wavelengths. The curvature of each surface is dictated by the aberrations in the color image created by the relay lens. Specifically, each surface is positioned so that its focus (86, 94) coincides with the focal point (58, 60) of the corresponding color component in an intermediate image (18) created by the relay lens so that the final virtual image (22) reflected by the combiner is longitudinally color corrected.

Abstract: A catadioptric reduction projection optical system having a structure capable of increasing a numerical aperture without increasing the size of a beam splitter and achieves excellent performance of a semiconductor manufacturing apparatus. The catadioptric reduction projection optical system comprises a first partial optical system having a first lens group, the beam splitter, a lens element, and a concave reflecting mirror to form an intermediate image of a first object, a second partial optical system for forming a reduced image of the intermediate image on a second object, the second partial optical system having a second lens group of a positive refracting power and arranged in an optical path between a second object surface and a surface on which the intermediate image is formed, and a third lens group arranged in an optical path between the beam splitter and the third lens group. The first lens group is arranged in an optical path between the first object and the beam splitter.

Abstract: An optical guide (10, 40, 50, 60) for horizontally aligning two vertically stacked images generated by one or two SLMs. The optical guide has a channel separator (10a) that directs both images along two different paths. A pair of aligning reflectors (10b and 10c) on each path vertically shift the images with respect to each other so that at least part of the images on the first path are aligned side-by-side with at least part of the images on the second path. The channel separator (10a) then redirects the images to the image plane 15. Along both paths, at least two of the reflecting surfaces of channel separator (10a) or aligning reflectors (10b and 10c) are optically powered so as to change the width or height of the images.

Abstract: It is an object of the invention to provide a catadioptric optical system with an arrangement for realizing a large numerical aperture and reducing the diameter of a concave mirror while ensuring a sufficient working distance on the image side, and also an exposure apparatus using this catadioptric optical system.A catadioptric optical system according to the invention includes a first imaging optical system for forming an intermediate image of a pattern on a first plane, a second imaging optical system for forming a reduced image of the intermediate image on a second plane, and an optical path deflecting member for guiding a light beam from the first imaging optical system to the second imaging optical system. The first imaging optical system has at least a first optical element group having a positive refracting power, and a second optical element group having a concave mirror and a meniscus lens component with a concave surface facing the first imaging optical system.

Abstract: A catadioptric optical system includes a first imaging optical system forming an intermediate image of a pattern provided on a first surface with a reduced magnification, including a first lens group with a positive refracting power and a second lens group which includes a concave mirror having a negative lens component. The system also includes a second image optical system forming an image of the intermediate image upon a second surface, a combined magnification of the first and second imaging optical systems being a reduction magnification. The system further includes a deflecting member disposed in an optical path from the first imaging system to the second imaging system so as to guide light from the first imaging system to the second imaging system.

Abstract: Various light collection systems (10, 20, 30), for providing light to be reflected from, or transmitted by, an SLM. Two systems (10, 20) include reflectors (11, 21), which are designed to collect rear-emitted light from a source, as well as lenses (12, 22) having low f-numbers and achromatic transmission, and may include an integrator (14, 23). A third system (30) includes a special reflector (31) coupled directly to an integrator (33).

Abstract: A scanning projection optical device is disclosed which can be constructed using relatively small optical members, which employs a catadioptric system that is advantageous to attain a high NA, and which has arc-shaped object and image regions located out of an optical axis and a projecting magnification of 1. In the scanning projection optical device, the catadioptric system is an optical system telecentric in both object- and image- field sections, and has a first, positive power lens-system, a second, substantially non-power lens-system, and a concave mirror; the first, positive power lens-system and the concave mirror cooperatively satisfy Petzval condition to correct field curvature; and without impairing the Petzval condition satisfied by the first lens-system and the concave mirror, the second lens-system corrects aberration of the arc-shaped region centering around the optical axis.

Abstract: This invention relates to a catadioptric optical system in which, a large numerical aperture is attained on the image side and, while securing a sufficient working distance, the size of the beam splitter is reduced, thereby attaining a resolution of a quarter micron unit, and an exposure apparatus using the same. In order to form a reduced image of a pattern of a first surface on a second surface, this catadioptric optical system comprises, at least, a first lens group, a beam splitter, a concave mirror having an enlarging magnification, and a second lens group. These constitutional elements of the catadioptric optical system are disposed such that light from the first surface passes through the first lens group, the beam splitter, the concave mirror, the beam splitter, and the second lens group in this order.

Abstract: A first partial optical system including a first group of lenses having a positive refractive power, a first concave reflection mirror and a second group of lenses having a positive refractive power, for forming a primary reduced image of an object, a second partial optical system including a second concave reelection mirror and a third group of lenses having a positive refractive power, for further reducing the primary reduced image and refocusing it, and a reflection mirror arranged between the first partial optical system and the second partial optical system, for deflecting a light path are arranged in a sequence as viewed from the object. A good image-forming ability as a projection optical system for fabricating a semiconductor device is attained with a simple construction.

Abstract: An illuminating optical apparatus for performing, e.g., oblique illumination has an arrangement in which an image of a reflecting mirror for reflecting a light beam from a light source is formed while being curved. With this arrangement, an annular secondary source with a light intensity distribution having moderate tails can be obtained.

Abstract: Illumination light having passed a pattern formed on a first surface enters a beam splitter directly or through a refracting system. On this occasion, inside the beam splitter, at least part of the illumination light having passed through an entrance surface is transmitted or reflected by a direction changing surface and then passes through an exit/entrance surface. Subsequently, the illumination light first leaving the beam splitter is reflected by a reflective surface of a concave mirror and then again enters the beam splitter. On this occasion, inside the beam splitter, at least part of the illumination light having passed through the exit/entrance surface is reflected or transmitted by the direction changing surface then to pass through an exit surface. The illumination light thus again leaving the beam splitter is projected directly or through a refracting system onto a second surface to form an image of the pattern thereon.

Abstract: Exposure light from a pattern on a first surface advances through a first converging group, is then reflected at the periphery around an aperture on a first plane mirror, thereafter is reflected by a second converging group including a first concave reflecting mirror, and forms a first intermediate image of the pattern in the aperture of first plane mirror. A beam from the first intermediate image passes through a third converging group to form a second intermediate image of the pattern in an aperture of a second plane mirror. A beam from the second intermediate image is reflected by a fourth converging group including a second concave reflecting mirror, thereafter is reflected at the periphery around the aperture of second plane mirror, and then passes through a fifth converging group to form an image of the second intermediate image on a second surface. A projection optical system is arranged as described without using a beam splitter.

Abstract: A nonimaging radiant energy device may include a hyperbolically shaped reflective element with a radiant energy inlet and a radiant energy outlet. A convex lens is provided at the radiant energy inlet and a concave lens is provided at the radiant energy outlet. Due to the provision of the lenses and the shape of the walls of the reflective element, the radiant energy incident at the radiant energy inlet within a predetermined angle of acceptance is emitted from the radiant energy outlet exclusively within an acute exit angle. In another embodiment, the radiant energy device may include two interconnected hyperbolically shaped reflective elements with a respective convex lens being provided at each aperture of the device.

Abstract: A catadioptric optical system includes, in succession from the object side, a first partial optical system having positive refractive power and for forming the primary image of an object, and a second partial optical system having positive refractive power and for forming a secondary image by light from the primary image, and at least one aperture stop may be provided in the optical path of the first partial optical system and at least one aperture stop may be provided in the optical path of the second partial optical system.

Abstract: A reflection and refraction optical system includes a planner beam splitter, a concave mirror and a lens group, for imaging a fine pattern of a reticle upon a wafer, wherein a lens element of the lens group is disposed eccentrically with respect to an optical axis of the system by a predetermined amount or a parallel plate is disposed obliquely with respect to the optical axis, so as to produce a comma or distortion effective to cancel the comma or distortion produced by the beam splitter.

Abstract: A Dyson lens system includes a radiation source, a concave mirror, and a plano-convex lens. There is also incorporated in the system an additional lens that is spaced from the plano-convex lens a large part of the distance from the plano-convex lens to the mirror. A roof prism and a turning prism are provided to conduct radiation from the radiation source to the plano-convex lens and also from the plano-convex lens to an image plane. An image adjustor or compensator is provided between the prisms and either the image plane or an object plane--the latter being disposed between the radiation source and the prisms. An adjustment mechanism is provided to effect highly accurate adjustment of the location of the image, the adjustment mechanism including physical shifting to a slight degree of a portion of one or both prisms.

Abstract: An optical system to project an image from an illuminated object to an image plane with a selected magnification factor. This system includes a lens system having a fixed magnification factor and at least one flat plate that is optically compatible with the lens system and which when bent into a cylindrical shape varies the fixed magnification factor of the lens system along one axis of the image. This variable magnification technique is applicable to all lens system types, including a Wynne Dyson type projection system. In addition, a Wynne Dyson optical projection system that includes an optical block in place of the usual fold prism is discussed. The optical block reduces changes in distortion caused by heat transferred from the reticle. The block permits the inclusion of a dichroic beamsplitter diagonally through the optical block which presents minimal attenuation of the exposure illumination.

Abstract: A catadioptric optical reduction system for use in the photolithographic manufacture of semiconductors having a concave mirror operating near unit magnification, or close to a concentric condition. A lens group before the mirror provides only enough power to image the entrance pupil at infinity to the aperture stop at or near the concave mirror. A lens group after the mirror provides a larger proportion of reduction from object to image size, as well as projecting the aperture stop to an infinite exit pupil. An aspheric concave mirror is used to further reduce high order aberrations. The catadioptric optical reduction system provides a relatively high numerical aperture of 0.7 capable of patterning features smaller than 0.35 microns over a 26.times.5 millimeter field. The optical reduction system is thereby well adapted to a step and scan microlithographic exposure tool as used in semiconductor manufacturing.

Abstract: A concentric optical system usable as either an imaging optical system or an ocular optical system, which has an F-number of 1.5 to 3 and enables a flat and clear image to be photographed or observed at a view angle of up to 60.degree. or more with substantially no aberration. The concentric optical system includes at least two semitransparent reflecting surfaces (2) and (3) each having a center of curvature disposed in the vicinity of a pupil (1) and a concave surface directed toward the pupil. The semitransparent reflecting surfaces are disposed so that each semitransparent reflecting surface passes each particular bundle of light rays at least once and reflects them at least once, thereby providing a flat image surface (4).

Abstract: The present invention is a viewing assembly that can selectively create optical compound corrections in the images reflected from the viewing assembly. The viewing assembly includes a reflective surface coupled to a supporting body in such a manner that the reflective surface conforms to the contour of the supporting body. The contour of the supporting body can then be selectively altered by the viewer of the viewing assembly, thereby changing the shape of the reflective surface and creating desired optical corrections in the viewed reflected images.

Abstract: A device for lighting a medical treatment field is disclosed and includes an optical member for focusing a plurality of light rays. The device also includes a prism assembly formed of a plurality of sectors of prisms. Each prism has an entry face and an exit face. The vertices of the sectors are substantially located in the center of the prism assembly. The sectors of prisms are configured and dimensioned so that the optical focusing member can focus the plurality of light rays generally onto the entry faces of the prisms. In addition, the device includes a mechanism for displacing at least a predetermined number of sectors such that the exit faces of the prisms of the predetermined sectors can be selectively positioned in one of a generally planar or a non-planar configuration. In an alternative embodiment, the device includes an optical focusing member and a prism assembly wherein the exit faces of the prisms are generally arc shaped along the length of the sector.

Abstract: A light emitting device assembled in a light transmitting type of photoelectric encoder is required to generate light having high parallelism and large quantity of light. This device uses one half of a concave mirror having a small aberration and long focal point. Hence, light radiated from a LED disposed at the focal point of the concave mirror has high parallelism. Further, using a plane mirror disposed at the optical axis of a concave mirror, light reflected with the plane mirror from a LED onto the concave mirror travels in parallel rays. Parallel rays, having a large quantity of light resulting from overlapping parallel rays, reflected from the concave mirror directly and indirectly from the light emitting element can be obtained.

Abstract: To develop a design form for a Cassegrain-type telescope with spherical primary and secondary mirrors, which is well-corrected for chromatic aberration as well as for geometrical aberrations including spherical aberration, coma and astigmatism, the designer begins with a "starting design form" for a conventional Cassegrain-type telescope with spherical primary and secondary mirrors, and then modifies the "starting design form" by:(a) positioning lens elements of a corrector lens group along an optic axis inside the front focal plane of the spherical primary mirror, where the lens elements of the corrector lens group are made of optical materials that enable a desired degree of correction for chromatic aberration to be achieved;(b) providing a reflective coating on a central portion of the back surface of the rear-most lens element of the corrector lens group, which replaces the secondary mirror of the "starting design form" and becomes the secondary mirror of the telescope;(c) locating the entrance pupil of t

Abstract: A wide-field exposure optical system in which the projection is performed by scanning an object to be projected with a predetermined scan width. The optical system comprises an illuminating section for illuminating the object to be projected in a circular arc region, a reflecting and refracting optical system for correcting the aberration of a circular arc region having its center on the optical axis and for forming, within an image surface, an image of the object to be projected illuminated by the illuminating section as a circular arc, a driving means for moving light-receiving members arranged on the object to be projected and on the image surface relative to the illuminating section and the reflecting and refracting optical system, and the reflecting and refracting optical system being formed by a first lens group, a second lens group and one concave mirror. The second lens group comprises a second lens which is a convex lens and a third lens which is a concave lens.

Abstract: The invention is directed to a catadioptric reduction objective having a concave mirror, a beam splitter and several lens groups but without an additional lens group disposed between the concave mirror and the beam splitter. Catadioptric reduction objectives are disclosed having an image-side aperture of 0.52 and 0.58 for an imaging scale of 1:4 and are corrected for an unrestricted excimer laser for use in submicronlithography.

Abstract: A folded, magnifying, front projection arrangement for video displays includes a video image source, such as a flat panel display unit out of the user's field of view, projects its image onto a concave mirror also out of the user's field of view. The video image source is maintained off-axis with respect to the optic axis of the concave mirror and at a distance from the concave mirror between one and two times the distance from the concave mirror to its principal focal surface, which would be the principal focal plane if the concave mirror were a spherical or a parabolic mirror. The concave mirror, in turn, reflects and focuses the light from the video image source onto a projection screen, within the user's field of view, resulting in a magnified image. The distortion of the projected image that would otherwise result from off-axis projection is compensated for by maintaining the plane of the video image source at a non-perpendicular angle to the optic axis of the mirror.

Abstract: A novel method for assessing a surface figure of an optical element. The method preferably comprises subjecting the optical element to a classical autocollimation testing procedure for ascertaining its surface figure relative to a predetermined ideal. The testing procedure is characterized by a step of modifying the classical optical testing procedure, so that the optical element under test simulates a paraboloid.

Abstract: There is provided an improved optical viewing device (10) in which variable compass heading information (80) and stadiametric range measuring information (88), (106), (118) is superimposed upon the image of a scene viewed through a viewing optical system (13) within the device (10). A self-luminous display panel (36) displays the information in the form of graphical symbols and/or alphanumeric characters. A folding lens (38) reflects light from the display panel (36) to a correcting lens (40), which transmits the light to a reflecting means (41) or (52). The reflecting means (41) or (52) reflects the light to a mangin mirror (44) or (62), which reflects the light to a dichroic combiner (28) or (50). The dichroic combiner (28) or (50) transmits the light into the path of the viewing optical system (13) such that the information displayed on the display panel (36) is effectively superimposed upon the image of the scene viewed by the user.

Abstract: A pupil/image reversal prism (FIG. 2) forms a pupil at an image location. Such a prism has specific applicability in a DCR scheme for a thermal imaging system (FIG. 3a, 31 and 32) in which a passive DCR source is implemented by a pupil imager that forms a pupil onto the image of a thermal scene, thereby providing scene-average radiation to a thermal detector array. The pupil/image reversal prism including an input reflective surface (A), an output reflective surface (B) , a positive reflective surface (C) and an intermediate folding reflective surface (D). The reflective surfaces A and B use total internal reflection to provide both transmissive and reflective operation.