Abstract: A method for making a fresnel lens on a substrate by forming a plurality of annular rings. Each ring has a plurality of steps, with each step having an inner wall and an outer wall, and an upper surface.

Abstract: A wide angle lens is made of three groups so as to satisfy a predetermined conditional expression concerning abbe number, thereby making it telecentric and yielding no eclipse in its peripheral luminous flux. Also, an apparatus accommodating it is made compact as a whole. This wide angle lens comprises, arranged in the following order from the screen side toward the liquid crystal side, a first lens group composed of a concave lens (L1), whose concave surface having a large radius of curvature is directed toward a smaller conjugate side (liquid crystal panel), and a convex lens (L2); a second lens group composed of one concave lens (L3) and two convex lenses (L4) and (L5); and a third lens group composed of a Fresnel lens (L6) which is disposed near a liquid crystal panel (L7; 4). The abbe number .nu. 1 of the lens L1 which is the concave lens in the first lens group is 57.8, whereas the abbe number .nu. 2 of the lens (L3) which is the concave lens in the second lens group is 25.

Abstract: An optical device having a variable index of refraction across its surface includes a light transmissive material with a plurality of regions in the light transmissive material. Each region has an index of refraction which is different from the remainder of the material. The regions may be arranged in the surface of the material such that the density of the regions on the surface varies across the surface. Each region may be a bore, including a hole that extends through the light transmissive material. Variations in the density of the regions or bores as well as the depth and shape of the bores may be utilized to create variations of the refractive index within the light transmissive material. The regions form a refractive lens.

Abstract: UV-curable Fresnel lens resin compositions ?1a! comprising a (meth)acrylate containing hydroxyl group and aromatic ring (A1), a urethane group-containing (meth)acrylate (A2) comprising an aromatic diol, an aromatic ring-containing monofunctional (meth)acrylate (A3), and a photopolymerization initiator (B) and ?1b! comprising (A1), a mono- or di(meth)acrylate monomer (A4), and (B), further supplemented with a polyester (C1) comprising an aromatic diol and a phosphate (C2) for the formation of a Fresnel lens on a sheet or plate made of a methyl methacrylate (co)polymer; a Fresnel lens formed by UV cure of composition ?1a! or ?1b!; and a rear projection screen including a sheet or plate carrying said Fresnel lens. The Fresnel lens has high refractive index, antistatic properties and is satisfactory in adhesion to a sheet or plate.

Abstract: A head-coupled display device for use in presenting electronically generated visual images to a viewer. The device includes a headpiece worn by a viewer, and an image display screen mounted in the headpiece for presenting electronically generated images. A fresnel lens is positioned adjacent the screen for focusing images from the screen at a selected position for viewing as a virtual image. The lens has a set of concentric converging rings whose surface curvatures act to minimize rectilinear distortion of the virtual images perceived by the viewer over the entire field of view of the image.

Abstract: An optical system for magnifying a display panel includes a magnifying lens disposed in front of a display panel. The magnifying lens is constructed with two lenses respectively having convex surfaces opposite each other. At least one of the two convex surfaces is aspherical. A transverse aberration of the magnifying lens is less than the diameter of the pupil of an eye at a point where the eye is positioned. The lens for the optical system is a Fresnel lens whose vortex center is located on its edge. An apparatus for magnifying display panels according to the invention includes an instrument to be viewed distantly and instruments to be viewed not distantly. The instrument to be viewed distantly is disposed distant from the Fresnel lens under a center portion of the Fresnel lens, whereas the instruments to be viewed not distantly are disposed close to the Fresnel lens under an edge portion of the Fresnel lens.

Abstract: A projection system wherein two or more separate display sources, such as high brightness sources, or active matrix liquid crystal display (AMLCD) or other flat panel displays are used to write information directly onto a display screen, or onto a photoactivated reflective light valve for projection onto the display screen. Sequential imaging apparatus is used to alternately generate first and second images for display. For example, such images are coupled to the photoactivated reflective light valve and an illumination source is employed to illuminate the light valve and project a composite image onto the display screen. The flat panel displays may be transmissive, reflective, or self-emissive with the use of an optical shutter. A writing illumination source is used for non-self-emissive flat panel displays. Using high brightness display sources, the images may be directly written onto the display screen without the use of the reflective photoactivated light valve and the illumination source.

Abstract: An imaging optical system comprising at least one diffractive optical element having a positive refractive power, at least one refractive optical element having a positive refractive power and at least one refractive optical element having a negative refractive power; and characterized in that it favorably corrects aberrations, in particular, chromatic aberration.

Abstract: A method for making a fresnel lens on a substrate by forming a plurality of annular rings. Each ring has a plurality of steps, with each step having an inner wall and an outer wall, and an upper surface. The first step is formed on the substrate, and successive steps are formed at least partially on the upper surface of the previous step such that the outer wall of each successive annular step is offset from the outer wall of the previous annular step in an outward radial direction.

Abstract: An objective lens for an optical disk drive is disclosed. The objective lens comprises four portions each having a aspherical surface for focusing a light beam of a designated wavelength to a designated focal point. The first portion has a first aspherical surface that focuses the light beam to a first focal point. The second portion has a second aspherical surface that focuses the light beam to a second focal point. The third portion has a third aspherical surface featuring the same surface curvature characteristics as that of the first aspherical surface and focuses the light beam to the first focal point. And, the fourth portion has a fourth aspherical surface featuring the same surface curvature characteristics as that of the second aspherical surface and focuses the light beam to the second focal point. The objective lens can be made as a single-piece lens that suffers no energy loss for either focusing.

Abstract: A large aperture projection lens is disclosed which contains a TESSAR lens set and a FRESNEL lens. The TESSAR lens set consists of four lenses which satisfy the conditions of: Nd1>1.7; Nd2>1.7; and 33<Ud2<35. Nd1 is the refractive idex of a first lens at the wavelength of 0.5876 um; Nd4 is the refractive idex of a fourth lens at the same wavelength; and Ud2 is the Abbe number of a second lens. The FRESNEL lens is provided such that the following relationship is observed: ##EQU1## where Ff is the focal distance of the FRESNEL lens and Ft is the focal distance of the TESSAR lens set. The projection lens satisfies the following requirements while allowing the aperture to be as high as F/2.4, (i) when a color image is projected, the color differential is smaller than 25 um; (ii) the ratio between the brightness at an edge of the image and the brightness at the center of is greater than 60%; (iii) the distortion is smaller than 1%; (iv) the resolution is greater than 50% at 4 lps/mm.

Abstract: A rear-projection screen having at least a Fresnel lens and a light-diffusing member, and is characterized by having vertical-direction light diffusion properties greater at its upper and lower end portions than at its middle portion. For example, the light-diffusing member contains light-diffusing fine particles and has a vertical lenticular lens that diffuses light in the vertical direction, provided on the light-incident surface of the Fresnel lens. This decreases the rainbows caused by misdirected light and also improves the brightness at the border, without causing a lowering of peak gain.

Abstract: A projection system includes a collection lens that minimizes apparent magnification of the light source, so that the resulting system more nearly conforms to a point source idealization. Attendant benefits include improved collimation, a smaller projection lens, and a greater depth of focus. The collection lens is desirably of a "wrap around" configuration to maximize light collection while contributing to reduced source magnification. The opposite side of the collection lens can be provided with a convex lens of Fresnel form. Use of the Fresnel optic moves the principal plane of the collection lens closer to the light source, further minimizing the source's apparent magnification. The projection system additionally includes condensing optics formed with a deliberate asymmetry so as to provide more uniform illumination of a rectangular image plane. The Fresnel surface of the collection lens can be designed to provide this asymmetry.

Abstract: A foldable screen display for displaying screen images is disclosed which comprises: (a) at least two sub-displays; (b) a hinging member for pivotally connecting the sub-displays together on a side-by-side manner; (c) a magnifying optical element provided on top of each of the sub-displays, the magnifying optical element providing a magnifying power of between about 1.05 and about 1.3 so as to cause images displayed on the sub-displays to be perceived by a user as if they were from a single display; and (d) a membrane covering both of the sub-displays and the hinging member, the membrane being made of a transparent and resilient material. In a preferred embodiment, the magnifying optical element is a zone plate type magnifying optical element and is constructed to provide a magnifying power approximately equalling to one plus the ratio between the width of the hinging member and the width of sub-display.

Abstract: A wide angle zoom lens suitable for use in cameras for providing sufficiently wide range of field angles to cover a frame of a film in the camera provides performance comparable to zoom lenses having more elements. The wide angle zoom lens has four elements in three groups which are moveable with respect to each other. The front group has a diffractive lens formed on a curved surface thereof. The second or intermediate group and the front group has surfaces are aspheres for aberration correction as does a surface of a single element third group. Chromatic aberration is corrected by the diffractive lens in combination with the lens of the other groups over the zoom range. The third group lens is formed with glass with lower dispersion (higher Abbe number) than the lenses of the other groups. The second group has two lenses one of which may be a low power, negative, meniscus lens which is made of plastic thereby further reducing the cost of the zoom lens.

Abstract: In order to reduce complexity and cost of fabrication of zoom lenses, the real image forming lens group module at the front of the zoom lens is replaced with a two-element group where one of the elements has a diffractive lens on a curved surface thereof instead of the usually cemented doublet of the front group, but with substantially the same aberrations as a front group with three elements, including a cemented doublet. Aberrations (chromatic and monochromatic) produced by the first and second groups remain corrected by the combination of these groups over the zoom range of the lens. A second group housing two-elements, one of which has a curved surface on which a diffractive lens is provided, may be also be used to replace the three-element second lens group and particularly the cemented doublet thereof.

Abstract: An optical system with an optical unit consisting of a transmission unit with at least one transmission element for emitting optical radiation, a receiving unit with at least one receiving element for detecting optical radiation and an optical path for transmitting the optical radiation between transmission unit and receiving unit. At least one optical unit is located in the optical path to bundle and deflect the optical radiation and an optical body/optical bodies is/are assigned to either the transmission unit or the receiving unit. The optical bodies are designed as a kind of Fresnel lens and have an unstructured surface side and a structured surface side having indentations with steep flanks large slope angle and a small prism angle.

Abstract: A segmented axial gradient array lens is provided. In one embodiment, the segmented array lens includes two sheets of optical material which mate at opposing faces which have a series of corresponding parallel grooves and ridges. At least one of the sheets has an axial gradient index of refraction profile. This provides the functionality of a series of parallel cylindrical lenses. The array lenses may include one or more additional intermediate sheets which may have a homogeneous or axial gradient index. With the first and last sheets having an axial gradient index of refraction, and the grooves forming the first and last interfaces between the sheets being rotated 90 degrees relative to each other, a two dimensional array of point foci can be provided. An array of cones and conical indentations can be used at the interfaces to provide the functionality of an array of spherical lenses. An array lens of the invention can be used to provide an optical multiplexer.

Abstract: The present invention provides a screen assembly wherein measures are taken to prevent slack produced in a lenticular lens sheet due to temperature changes and gaps created between a Fresnel lens sheet and the lenticular lens sheet due to temperature changes, thereby enabling the display of images free of inconsistencies in color. The structure of the screen assembly has the lower parts of a lenticular lens sheet and a Fresnel lens sheet comprising a screen fixed together, the upper part of the light radiant side of the lenticular lens sheet fixed to the upper part of a framework, the lower part of the screen, where the Fresnel lens sheet and the lenticular lens sheet are put together not being fixed to the lower part of the framework and a specified clearance created between the lower part of the screen and the lower part of the framework.

Abstract: A method for mass-producing eccentric Fresnel lens sheets comprising the steps of: preparing a number of concentric Fresnel lens sheets; dividing the concentric Fresnel lens sheets into a first set and a second set each including a plurality of Fresnel lens sheets; cutting out a plurality of first sheets each corresponding to one portion of the eccentric Fresnel lens sheet from each of the Fresnel lens sheets of the first set; cutting out a plurality of second sheets each corresponding to the other portion of the eccentric Fresnel lens sheet from each of the Fresnel lens sheets of the second set; and bonding each of the first sheets and each of the second sheets in such a manner that patterns on the first sheet and the second sheet are continuous to prepare a plurality of eccentric Fresnel lens sheet. The second set can include a third set and a fourth set and a plurality of third sheets are cut out from the third set and a plurality of fourth sheets are cut out from the fourth set.

Abstract: A wide angle lens for a vehicle rear window is movably held in a guide device which is fixed to the body of the vehicle. The lens can be moved out of the rear view field of vision of the driver for normal forward driving namely, it can be moved along the guide device. The lens is brought into the rearward field of vision only when the vehicle is to be maneuvered in reverse.

Abstract: A motion activated light fixture has a housing comprised of a canopy, a base formed integral with the canopy and at least one illumination source mounted on the housing. The housing has a centrally located mounting hole which enables the base and canopy to be rotated 360 degrees around the mounting hole prior to being mounted on a selected vertical or horizontal surface. The sensor component mounts on an outer surface of the housing and includes a lens plate in which plural lens segments are formed in a plurality of rows so as to provide a substantially wide angle of view of up to 180 degrees and which view can be variably positioned utilizing the referred to mounting hole configuration.

Abstract: An objective lens system comprising at least one diffractive optical element, having a high magnification and a large numerical aperture, and capable of favorably correcting aberrations, in particular, longitudinal chromatic aberration and lateral chromatic aberration.

Abstract: An improved zoom lens for use in projective image forming systems is disclosed. It comprises, in the order from the object side to the image side, a first lens group with a negative refractive power, a second lens group with a positive refractive power, a third lens group with a negative refractive power, and a fourth lens group with a positive refractive power. The lens groups are disposed such that, during the zooming operation from the wide-angle mode to the telephoto mode, the first, second, and third lens groups are simultaneously moving toward the object side and the fourth lens group stays stationary, and that the first and third zoom lens groups are provided such that the following condition is satisfied: 1.6<k1/k3<4, where k1 is an absolute value of the refractive power of the first lens group and k3 is an absolute value of the refractive power of the third lens group. In a preferred embodiment, the fourth lens group comprises a Fresnel lens.

Abstract: A projection lens system with a high resolving power and a wide exposure area which is effectively corrected for various aberrations including chromatic aberration and which is compact and has minimal production problems in a case where there is a limitation on vitreous materials usable as a lens material. The projection lens system (10) includes a plurality of lenses, at least one of which is a diffractive optical element (DOE) (11). The DOE (11) has a pitch arrangement in which it has a positive power in a paraxial region thereof, and wherein the positive power continuously changes to a less positive power, and then to a negative power as the distance from the optical axis of the DOE (11) increases toward the periphery thereof. Since the DOE (11) produces large aberrations which are opposite in sign to aberrations produced in the refracting system, it is possible to effectively correct various aberrations in the projection lens system (10) and also axial chromatic aberration.

Abstract: A projection lens assembly having an imaging lens group, including a first lens group having a positive refractive power, a second lens group having a positive refractive power, and a Fresnel lens group having a positive refractive power and at least one Fresnel lens surface, in this order from the enlargement side. The projection lens assembly satisfies the relationships 1.4<f.sub.1 /f<2.8, and 1.5<f.sub.2 /f<6.0. In these relationships, f represents the focal length of the whole lens system, f.sub.1 the focal length of the first lens group, and f.sub.2 the focal length of the second lens group.

Abstract: An optical rear view system for a vehicle, having a reflector mounted to receive light from objects to the rear of the vehicle and to reflect it towards an observer, is provided with at least one further optical component between the reflector and the observer effective to direct towards the observer, by refraction or reflection, a portion of the light which upon reflection at the reflector is not directed towards the observer, whereby to provide a wider field of view than that obtainable from the reflector alone. The reflector is positioned forwardly of the observer so as to be in his field of view and the surface of the system on which light from an object behind the vehicle is first incident lies at an acute angle to the longitudinal axis of the vehicle and is inclined such that a forward part of the incident surface is further from the vehicle axis than a rearward part.

Abstract: Optical system intended to enlarge images, such as those produced by a television set. For this purpose is used an optical system such as an assembly including at least one thick lens (12) or its equivalent (for example a Fresnel lens), placed very close to the image (10) to be enlarged, that allows an enlarged image to be obtained, with the possibility for the observer (13) to move throughout a sufficiently wide zone while still observing an image without troublesome deformation.

Abstract: A low-profile transmissive overhead projector employs a folded optical path and an off-axis Fresnel lens condensing system which includes a catadioptric lens element. This lens provides a fast condensing system which allows collimation, dispersion, or concentration of light striking the lens at a high angle of incidence, with efficient transmission to the far edge of the lens. This also enables additional reduction in the OHP base height by allowing the single mirror to be mounted at a flatter angle, with the light source still maintained at a position below (and adjacent) the stage. A novel catadioptric lens design further imparts achromaticity to the element, so that it may be constructed of any material, regardless of its index of refraction. The condensing system may have a single or doublet catadioptric lens.

Abstract: A resin layer having an improved durability may be obtained by curing a photocurable resin composition, including: (A) a polyfunctional urethane-modified polyester (meth)acrylate comprising a polyester oligomer and a plurality of (meth)acryloyl groups bonded to the polyester oligomer via a urethane group, and having a number-average molecular weight of at least 700, (B) a polyfunctional (meth)acrylate having a number-average molecular weight of less than 700, (C) a monofunctional (meth)acrylate, and (D) a photopolymerization initiator. The cured resin layer shows a Young's modulus which shows a small temperature-dependence, and reduces the possibility of peeling of an optional overcoating layer formed thereon.

Abstract: In a stepped lens with a Fresnel surface structure produced by lithography and a process for fabricating same, the high potential exposure speed of high-speed electron-beam exposure systems which work with variable rectangular beam cross sections is converted in such a way that stepped Fresnel type lenses can be fabricated with high efficiency and, in so doing, the required amounts of data is reduced. According to the invention, radiation dose distributions which correspond to cylindrical lenses are exposed one upon the other, at least one of the radiation dose distributions corresponding to a Fresnel type cylindrical lens.Lens structures with any desired lens curvature, from radially spherical to elliptical, can be efficiently produced by lithography by the disclosed process.

Abstract: A lens segment used in passive infrared motion detectors is disclosed. A preferred embodiment has semi-circular rings separated by grooves. The semi-circular rings are offset about a separation axis passing through their centers or optical axes. The separation axis effectively divides the lens segment into two subsegments causing projection of two cross-sectional areas of coverage, one offset from the other. This increases the size of the projected cross-sectional area of coverage preventing a rodent near the lens from substantially filling the projected cross-sectional area of coverage, thus avoiding detection of the rodent.

Abstract: A daylighting system usable in either a skylight or a dormer includes a film having a plurality of negative Fresnel lenses.

Abstract: A cylindrical astigmatic lens is used conventionally in detecting focussing errors in an optical pickup system. The inventive astigmatic lens is comprised of an orthorhombic base, made of a refractive material, provided with two parallel surfaces and a centerplane perpendicular thereto, and two sets of M pentahedrons, made of the same refractive material, placed on one of the two parallel surfaces thereof in such a way that each set of M pentahedrons is symmetric with respect to the centerplane. Each of the pentahedrons consists of three rectangular surfaces and two right angled triangular side surfaces, each of the triangular side surfaces being defined by a height H.sub.m, a base R.sub.m and an inclination. Since the height is the same in all of the triangular side surfaces in the M pentahedrons, the dimension of each pentahedron in the inventive astigmatic lens is defined by R.sub.m, R.sub.m being expressed as ##EQU1## wherein f represents the focus length and .lambda.

Abstract: A low-cost, dual-view, immersible periscope that is particularly suitable for use as a toy or learning tool in environments such as bath tubs, sinks, tidal pools, outdoor wadding pools, or other aquatic areas where children play and explore. The periscope has an upper viewing compartment that operates in air and a lower compartment that floods with water as the periscope is immersed and contains the entrance aperture. The upper and lower compartments are separated from one another with a transparent window, which the upper compartment surrounds isolate its air space from surrounding water to provide a completely still image of activity taking place beneath the surface even though it may be turbulent with wave action. Additional enhancements include magnification, underwater accessory lighting, sound effects, torpedo tubes, and means for placing transparencies over the entrance aperture to integrate images with underwater action.

Abstract: A novel low-cost solar photovoltaic module using line-focus lenses and photovoltaic receivers incorporating high-performance photovoltaic cells is described. It consists of an array of linear arched Fresnel lenses with a linear photovoltaic cell receiver located along the focal line of each lens. The lens consists of a protective superstrate with molded silicone Fresnel grooves on its inner surface. The photovoltaic cell receiver consists of high efficiency cells interconnected in a string with a solid secondary optical element adhesive bonded to the cells. The entrance aperture of each secondary optical element is rectangular in shape and the optical secondaries are butted up against each other in a line to form a continuous entrance aperture along the focal line. In addition to providing more concentrated sunlight, the solid optical secondaries shield the cells against radiation damage.

Abstract: A staring sensor apparatus which includes an optics assembly for providing a panoramic field of view in which the field of view in one direction is considerably larger than the field of view in the direction perpendicular thereto. A two-dimensional focal plane assembly (FPA) collects and converts an incoming optical signal from the optics assembly to an electrical wave form which depicts the energy falling on each pixel of the FPA in a discrete unit of time. The resulting pixel outputs thus represent the energy emitted from specific calibratable around the optics assembly.

Abstract: Dispersive microlens apparatus and methods are used in one mode for detecting multiple, different wavelengths from a bandwidth of wavelengths (existing within an image plane blur spot) and are used in another mode for combining a plurality of different, emitted wavelengths into a bandwave of wavelengths (at a blur spot in an image plane).

Abstract: A zone plate focusing radiation comprises a plurality of surface portions (20a, 20b, 20c, 20d, 30) corresponding to zones of the zone plate. The surface portions are positioned in a plurality P of parallel planes such that each surface portion diffracts radiation out of phase with respect to adjacent surface portions such that radiation diffracted by the surface portion constructively interferes at a focus of the zone plate. The p.sup.th plane is dielectrically spaced from the first plane by n.lambda., where .lambda. is the wavelength of the radiation and n is an integer.

Abstract: An apparatus for using and a process of using a Fresnel zone plate array is utilized for processing materials. An optically stable frame receives coherent light and passes the coherent light through beam processing optics such as a collimator, a beam expanding telescope and an aperture. Thereafter, the beam is routed to scanning mirrors immediately overlying a Fresnel zone plate array. The Fresnel zone plate array has a plurality of discrete subapertures with each subaperture containing image information at a discrete working distance from the plate; each image produced by a subaperture of the Fresnel zone plate array typically differs from adjacent images from adjacent subapertures typically in size, shape or gain. The beam is scanned and registered to a discrete selected subaperture on the plate to cause an image from the subaperture to form on a work piece located at the working distance of a scanned subaperture.

Abstract: The present invention provides an impact resistant Fresnel lens comprising a resin which is obtained by polymerizing a solution consisting essentially of (a) 100 parts by weight of a monomer mixture comprising an styrenic monomer in an amount of from 60 to 99 parts by weight and a (meth)acrylic monomer of from 1 to 40 parts by weight, and (b) 1 to 50 parts by weight of a styrene-dienic copolymer based on 100 parts by weight of said monomer mixture based on 100 parts by weight of said monomer mixture. The Fresnel lens has a high refractive index and excellent transparency and impact resistance.

Abstract: Wavefront correction apparatus for correcting a stepped wavefront output produced by certain angles of scan and by certain positions of scan in scanning microlens arrays includes anamorphic transfer optics with diffractive corrections. The transfer optics form the outputs of all of the unit cell trains of the microlens arrays into a unique, separate, linear image at each position of scan of the scanning array. A stepped wavefront corrector is positioned in the path of each linear image, and selected thicknesses of the material in the stepped wavefront corrector are effective to vary the times of optical passage through the stepped wavefront corrector in amounts to restore the wavefront to a continuous, unstepped form at the outlet of the plate.

Abstract: A low-profile, transmissive overhead projector (OHP) employs a novel condensing lens system having a catadioptric Fresnel lens and a dioptric Fresnel lens. Each of the lenses exhibits chromatic aberration, but the dispersion of one lens is selected to cancel out the dispersion of the other, e.g., if the catadioptric lens has negative dispersion then the dioptric lens is selected to have positive dispersion. The mutual cancellation of the dispersion of each lens practically eliminates longitudinal chromatic aberration through the lens system. The lens system provides a fast condensing system which allows collimation, dispersion or concentration of light striking the lens at a high angle of incidence. This characteristic is particularly suited for a low-profile OHP as it allows the light source to be placed directly under, but very close to, the stage area.

Abstract: A low-profile transmissive overhead projector employs a folded optical path and an off-axis Fresnel lens condensing system which includes a catadioptric lens element. This lens provides a fast condensing system which allows collimation, dispersion, or concentration of light striking the lens at a high angle of incidence, with efficient transmission to the far edge of the lens. This also enables additional reduction in the OHP base height by allowing the single mirror to be mounted at a flatter angle, with the light source still maintained at a position below (and adjacent) the stage. A novel catadioptric lens design further imparts achromaticity to the element, so that it may be constructed of any material, regardless of its index of refraction. The condensing system may have a single or doublet catadioptric lens.

Abstract: Wavefront correction apparatus for correcting a stepped wavefront output produced by certain angles of scan and by certain positions of scan in scanning microlens arrays includes anamorphic transfer optics with diffractive corrections. The transfer optics form the outputs of all of the unit cell trains of the microlens arrays into a unique, separate, linear image at each position of scan of the scanning array. A stepped wavefront corrector is positioned in the path of each linear image, and selected thicknesses of the material in the stepped wavefront corrector are effective to vary the times of optical passage through the stepped wavefront corrector in amounts to restore the wavefront to a continuous, unstepped form at the outlet of the plate.

Abstract: A cross-over field-of-view composite Fresnel lens for use in an infrared detection system includes a plurality of Fresnel lens segments provided in first and second groups. The first group of Fresnel lens segments are constructed as grooves-in lens segments and arranged in the array as grooves-in lens segments (or, alternatively, are constructed as grooves-out lens segments and arranged in the array as grooves-out lens segments). The second group of the Fresnel lens segments are constructed as grooves-out lens segments but arranged in the array as grooves-in lens segments (or, alternatively, are constructed as grooves-in lens segments but arranged in the array as grooves-out lens segments).

Abstract: A die which can press-mold an accurate glass microoptical element such as a grating repetitively can be manufactured easily by adhering a thin film, having an inverse shape of the master of a micro-optical element, on the top flat plane of a hard base body and by forming a protective layer thereon. The die having an inverse shape of the master can press-mold glass repetitively. By press-molding glass with the die, a large number of reliable glass micro-optical elements of the same shape as the master can be produced at a low cost.

Abstract: An optical mask including a 2.pi.n phase shifter pattern, a .pi.(2n+1) phase shifter pattern, an intermediate phase shifter pattern which shifts the phase of an incident light by an angle between 2.pi.n and .pi.(2n+1), and a reversed intermediate phase shifter pattern which shifts the phase of an incident light by an angle being reversed by .pi. for the phase shift angle of the intermediate phase shifter pattern. The intermediate phase shifter patterns are formed in the vicinity of the reversed intermediate phase shifter patterns having light shielding films in between.

Abstract: The invention discloses a composition for forming lens, which contains urethane acrylate prepolymer based on tolylenediisocyanate as a principal material, and further said composition containing brome acrylate at least by 10 to 40 weight %, caprolactone denatured hydroxypivalic acid ester neopentylglycoldiacrylate by 3 to 20 weight %, and bis-(acryloxyethoxy)bisphenol A by 3 to 60 weight %, and refractive index of said cured product being 1.5 or more, further discloses a Fresnel lens using said composition, and a transmission screen 1, in which a Fresnel lens 3 is formed on a base material 2.

Abstract: A Fresnel lens formed of an infrared transmitting material has a grooved surface. The grooves all extend to the same depth, and the distances between successive grooves vary across the lens. In a circular lens, the grooves are concentric, and the distances between grooves nearer the center are longer than the distances between the grooves nearer the circumference. A substantial portion of the grooves have an aspherical surface.