Abstract: In an image pickup device, a single refractive index distribution lens having a refractive index distribution which is substantially proportional to the square of the distance from an optical axis in a cross-section vertical to the optical axis is provided as an imaging lens in the neighborhood of the imaging face of an image pickup element. Specifically, the positional relationship between the image pickup element and the lens is fixed by adhesion of organic solvent or the like. Further, an infrared-ray cut filter is formed on the light incident face of the refractive index distribution lens.

Abstract: A compact gradient index rod lens that can be manufactured without decreasing the amount of incident light. The gradient index rod lens includes a lens body radially distributing refractive indexes. The lens body has a cross sectional outline formed by removing at least part of a peripheral portion of an original lens body.

Abstract: A miniaturized lens array for unity magnification imaging comprises a plurality of rod lenses arranged in one row. An arrangement pitch D of the rod lenses is defined to satisfy (2 m+1)·D≦2.1 mm or 2.5 mm. An angle of aperture &thgr; of the rod lens is defined to satisfy &agr;D/6×{n·cos−1(−&agr;/2/m)+(4 m2/&agr;2−1)1/2}≦&thgr;≦&agr;D/2×(4/m2/&agr;2−1)1/2. The arrangement pitch D and angle of aperture &thgr; are defined in this manner, and it is therefore possible to obtain the lens array whose difference between a total width and effective lens width is equal to or smaller than 2.1 mm or 2.5 mm.

Abstract: Graded index lenses, methods, and devices are disclosed. In certain embodiments, he lenses are made from generally cylindrical glass members having a radially varying refractive index and have a pitch less than about 0.23. Other embodiments relate to graded index lenses having a pitch between about 0.23 and 0.25 and an index gradient less than or equal to 0.3.

Abstract: Methods and apparatus for producing fused silica members having high internal transmission are disclosed. The apparatus and methods are capable of producing fused silica having internal transmission of at least 99.65%/cm at 193 nm.

Abstract: A rod lens array having a structure in which a large number of rod lens elements are combined into one unit while the large number of rod lens elements are arrayed in a plurality of rows. The number N of lens rows and the degree m of overlapping of images are selected to satisfy the relation: {3(N−1)N/16}1/2<m≦{N(N+1)(28−N)/(9−N)}1/2/4 when m is equal to X0/D, in which D is the diameter of each lens, and X0 is the radius of a view field generated by each lens.

Abstract: An optical microscope includes a compound GRIN objective and a lens system. The compound GRIN objective is able to form an image of an object located near one end of the GRIN objective. The compound GRIN objective is configured to limit a lateral field of view for the image to a distance equal to the diameter of the GRIN objective. The lens system is positioned to form a magnified image of an image formed by the compound GRIN objective.

Abstract: An objective lens system consisting of a first lens unit having a negative refractive power and a second lens unit having a positive refractive power wherein the first lens unit or the second lens unit comprises at least one radial type gradient index lens element which has a refractive index distribution in a radial direction from an optical axis. This objective lens system favorably corrects chromatic aberration and other aberrations by adequately selecting a value expressing an Abbe's number and a refractive power of medium for the radial type gradient index lens element.

Abstract: A rod lens array for line scanning is provided that can reduce the degradation of image quality (i.e., vertical stripes (streaks) in the sub-scanning direction of an output image) caused by a periodic irregularity in the light quantity, considering an angular aperture and the positional deviation of an image line in the sub-scanning direction. A rod lens array for one-to-one imaging is used as the rod lens array for line scanning, including a plurality of columnar rod lenses having a refractive index distribution in the radial direction that are arranged in one row in the main scanning direction with their optical axes in parallel. The effective overlapping degree m is in the range defined by (1.55+0.5j)D/d≦m≦(1.80+0.5j)D/d  Eq. 37 where d is the lens diameter of the rod lens and D is the array pitch of the rod lenses.

Abstract: A GRIN fiber lens has a silica-glass core whose refractive index has a radial profile. The profile has a radial second derivative whose average magnitude in the core is less than about 1.7×10−6 microns−2 times the value of the refractive index on the axis of the GRIN fiber lens.

Abstract: The invention relates to a focusing device comprising a Luneberg lens comprising a homogeneous volume of dielectric. It is characterized in that the dielectric comprises a granular agglomerate defined by a homogeneous granule size distribution of thermoplastic granules, at least one plurality of these granules being welded together by granule boundaries in order to keep said volume consolidated. Particular application to lenses for the tracking of nongeostationary satellites, of at least one geostationary satellite, or for use in an MMDS system.

Abstract: A GRIN fiber lens has a silica-glass core whose refractive index has a radial profile. The profile has a radial second derivative whose average magnitude in the core is less than about 1.7×10−6 microns−2 times the value of the refractive index on the axis of the GRIN fiber lens.

Abstract: An optical scanning lens used in a scanning and imaging optical system in which a beam deflected by a light deflector is condensed on or in the vicinity of a surface to be scanned. The optical scanning lens is formed through plastic mold, and a distribution of the refractive indexes &Dgr;n(x) inside of the optical scanning lens has a local maximum within a range through which the beam passes through the lens.

Abstract: An imaging optical element is comprised of a gradient index rod lens 12 of which external peripheral surface is a smooth surface without being processed by means of a flare-cut treatment and a field limitation stop member 14 mounted on the lens surface at the incidence side thereof. As for the stop member, the length t thereof is: t>1o·D/2X (where, 1o: a lens working distance, D: a rod lens diameter, X: a radius of field of view), whereby the angle of incidence of beam &thgr; at the center of the lens satisfies &thgr;<tan−1(X/1o) . It is effective especially when an application thereof is made to a rod lens array comprised of a plurality of rod lenses arranged into an array.

Abstract: A graded index lens is obtained by treating a raw glass material having a rod shape by ion exchange using silver to form a refractive index distribution in the radial direction of the rod, wherein the raw glass material comprises a glass composition of the following components: 15<Na2O≦30 mol %; 10<Al2O3≦25 mol %; 27.5≦SiO2≦55 mol %; 3≦B2O3≦18 mol %; 2.5≦MgO≦18 mol %; 0≦Ta2O5≦5 mol %; 0≦La2O3≦3 mol %; 0≦BaO≦3 mol %; and 0≦ZrO2≦3 mol %.

Abstract: An optical system includes a diffractive optical element in which a phase given to incident light from an optical axis toward the peripheral part in the radial direction is not reversed in an effective area and an absolute value of optical power on the optical axis is made minimum. In the optical system, chromatic aberration of magnification of a high order is satisfactorily corrected and flare caused by additional diffraction light (unnecessary diffraction light) is suppressed to as minimum as possible while maintaining a high imaging performance up to peripheral part of a field angle.

Abstract: An SiO2-TiO2-Li2O-Na2O-based glass composition containing no lead oxide having incorporated therein specific amounts of specific components which are selected from oxides of the metal elements having an atomic number of 30 (Y) to 73 (Ta) and which hardly cause coloration of glass. The glass composition has a desirable refractive index, hardly undergoes devitrification, and hardly develops cracks on ion exchanging and is suitable as glass for a graded index lens.

Abstract: A color image scanner is constructed by a three primary color LED array (4) for illuminating an original (2) to be read out, a monochromatic image sensor array (3) and a rod lens array (1) disposed between the original (1) and the image sensor array (3). The focusing parameters of the three kinds of refractive index distribution type rod lenses (11, 12, 13) constituting the rod lens array (1) are set so that each of the operating wavelength band and the predetermined wavelength is different among the kinds, the lens length Zo is equal among the kinds, and the conjugate length TC at each predetermined wavelength is substantially equal among all the kinds. Accordingly, when a color image reading operation is carried out by using the rod lens array which is effective in compactness and brightness, the chromatic aberration of the rod lens array can be sufficiently reduced and high-resolution can be implemented at low cost.

Abstract: A high performance optical imaging system can be provided by minimizing the overlapping degree m, increasing the quantity of light of the rod lens array and improving the resolving power while taking into account the irregularity of the quantity of light when a dislocation between a sensor and an optical axis of an entire rod lens array occurs. In the optical imaging system, a plurality of rod lenses with a refractive index distribution in the radial direction are arranged in two rows in a rod lens array with their optical axes in parallel to each other. This optical imaging system focuses light from a manuscript plane onto an image plane, the planes being arranged on the two sides of the rod lens array. The overlapping degree m defined as the following equation (Eq. 10) is in a range of 0.91≦m≦1.01; m=X0/2R   (Eq. 10) wherein X0 denotes an image radius that the rod lenses project onto the image plane and 2R denotes a distance between the optical axes of neighboring rod lenses.

Abstract: A single element objective lens for an optical disc drive converges a laser beam, which is emitted by a laser source, on a data recording surface of an optical disc through a protective layer of the optical disc. One surface of the objective lens is divided into a central area including an optical axis thereof and a peripheral area surrounding the central area. The peripheral area is provided with a diffraction lens structure formed by a plurality of concentric annular zones including minute steps. The central area is a continuous surface having no stepped portions. The diffraction lens structure compensates for variation of converging characteristic of the objective lens due to a change of a temperature.

Abstract: A rod lens array for line scanning is provided that can reduce the degradation of image quality (i.e., vertical stripes (streaks) in the sub-scanning direction of an output image) caused by a periodic irregularity in the light quantity, considering an angular aperture and the positional deviation of an image line in the sub-scanning direction. A rod lens array for one-to-one imaging is used as the rod lens array for line scanning, including a plurality of columnar rod lenses having a refractive index distribution in the radial direction that are arranged in one row in the main scanning direction with their optical axes in parallel.

Abstract: The invention presents an optical imaging system, which eliminates portions of an image with large image curvature, improving the resolving power. A plurality of columnar rod lenses 1 with a refractive index distribution in the radial direction is arranged in one or more rows in a rod lens array 2 for one-to-one imaging with their optical axes 1a in parallel. An object plane 3 and an image plane 4 are arranged on the two sides of the rod lens array 2, constituting an optical imaging system. Rectangular aperture stops 5 are provided on both faces of the rod lenses 1, so that they cover both end portions of the rod lenses 1 in the Y-axis direction (longitudinal direction of the rod lens array 2).

Abstract: The present invention is a method of making a lithography photomask and photomask blank. The method of making the lithography photomask and photomask blank includes providing a silicon oxyfluoride glass tube having an OH content less than 50 ppm. The method further includes cutting the silicon oxyfluoride glass tube, flattening the silicon oxyfluoride glass tube, and forming the flattened cut silicon oxyfluoride glass tube into a photomask blank having a planar surface. The present invention includes a glass lithography mask preform. The glass lithography mask preform is a longitudinal silicon oxyfluoride glass tube that has an OH content ≦10 ppm, a F wt. % concentration ≧0.5 wt. %.

Abstract: Objective lens optics that can realize NA higher than 1.623 without suffering from increased aberrations and which can be manufactured in a sufficiently smaller size to be suitable for use in an optical head on optical disk systems. The optics is made up of the combination of a single gradient index lens (1) having a gradient refractive index in a radial direction thereof and a single planoconvex lens (2) having a homogeneous refractive index. The gradient index lens has a planar or convexospherical lens surface. The planoconvex lens is made of a material whose refractive index (n) is greater than 2.2; it has its convex surface opposed to the gradient index lens such that the optical axes of the two lenses are aligned. Typically, the gradient index lens is provided on the object side and the planar surface of the planoconvex lens on the image side to make the optics suitable for use as an objective lens in optical heads.

Abstract: A set of lens systems consisting of a plurality of different kinds of lens systems each comprising a radial type gradient index lens element(s), wherein the radial type gradient index lens elements have a common refractive index distribution.

Abstract: An endoscope having a distally disposed lens and an optical transmission system which transmits the image of the lens to the proximal end of the endoscope is provided. The transmission system includes at least one reversing system, which includes two elements in mutual mirror-inverted arrangement. Each element includes a rod lens with planar faces and at least one optically thin lens having a planar surface. The rod lenses consist of an inhomogeneous material having a positive dispersion and an inhomogeneous refractive index in the radial direction, while the thin lenses are plano-convex lenses.

Abstract: Single homogeneous planoconvex lens 10 having a uniform refractive index is combined with single distributed-index lens 12 having its refractive index distributed in a radial direction and the object plane, the homogeneous planoconvex lens, the distributed-index lens and the image plane are arranged in that order along the optical axis. Both surfaces of the distributed-index lens are planar and the homogeneous planoconvex lens has its convex surface directed toward the distributed-index lens and the planar surface toward the object. Various characteristics of the two lenses are so specified as to provide an angle of view greater than 50°.

Abstract: Optical components have a material-distribution gradient due to nanometer-size particles embedded in a solid matrix. The components are manufactured by forming a dispersion of nanometer-size particles in a liquid, curable matrix material, causing the particles to migrate in the matrix material on the basis of a potential difference to form a distribution gradient, and subsequently curing the matrix material, retaining the distribution gradient. The method is suitable for use in the manufacture of optical lenses with a refractive index gradient.

Abstract: The transparent article with radial gradient index, according to the invention, comprises a matrix made of a first transparent polymer having a first refractive index n1 and a first Abbe number &ngr;1, a second transparent polymer, diffused into the first polymer in order to produce the radial gradient index and having a second refractive index n2, different than the first refractive index, and a second Abbe number &ngr;2, characterized in that it furthermore comprises an effective amount of an Abbe number modifier agent which reduces by at least 10%, preferably by at least 15%, and more preferably by at least 20%, the value of the Abbe number of that of the first or second polymer which has the refractive index with lower value.

Abstract: A zoom optical system provides a series of lens units designed to allow for zooming with minimal change in aberration resulting from the movement of the lens units. Each lens unit has a plurality of lens units. One embodiment has, in order from the object side, a first lens unit having a negative refractive power, a second lens unit having a positive refractive power, a third lens unit having a positive refractive power and a fourth lens unit having a positive refractive power wherein the second lens unit has at least one gradient index lens element and the first lens unit is kept stationary during a change of magnification. Additional embodiments have more or fewer lens units and the refractive power of each lens unit is varied. In some embodiments, a lens unit other than the first lens unit is kept stationary.

Abstract: A non-phase separable glass material for fabricating a GRIN lens comprises 5-20 mole % boron oxide and ratio R of network modifiers in mole % to the network former boron oxide in mole % is in the range of about 1-1.5. The melted preform of such glass material is extruded through an opening to form a glass rod where the extrusion process eliminates bubbles that may be present in the preform. Neodymium oxide may be added in the frit material for forming the preform to reduce friction forces in the extrusion process and reduces the stress in the glass rod. Centerless grinding may be performed to control the diameter and roughness of the surface of the rod to control the diffusion parameters during the subsequent ion-exchange.

Abstract: A zoom optical system is disclosed. The zoom optical system provides a series of lens units designed to allow for zooming with minimal change in aberration resulting from the movement of the lens units. To achieve this goal each lens unit is has a plurality of lens units. By way of example, one embodiment of the present invention has, in order from the object side, a first lens unit having a negative refractive power, a second lens unit having a positive refractive power, a third lens unit having a positive refractive power and a fourth lens unit having a positive refractive power wherein the second lens unit comprises at least one gradient index lens element and the first lens unit is kept stationary during a change of magnification. Additional embodiments are described in which more or fewer lens units are used and the refractive power of each lens unit is varied. In some embodiments, a lens unit other than the first lens unit is kept stationary.

Abstract: A lens system comprising, in order from the object side, a first lens unit having a positive refractive power and a second lens unit having a negative refractive power, configured to change a focal length thereof by varying an airspace reserved between the first and second lens units, and suited for use in electronic image pickup apparatus. The first lens unit is composed only of a single homogeneous lens element and the second lens unit is composed of a single radial type gradient index lens element which has a positive power of medium.

Abstract: A lens system composed of a first lens unit, a second lens unit having a positive refractive power, a third lens unit having a negative refractive power, and a fourth lens unit having a positive refractive power. The lens system is composed of a small number of lens components and configured compact by disposing at least one radial type gradient index lens component in the second lens unit and selecting an adequate refractive index distribution for the radial type gradient index lens component.

Abstract: In a three-lens configuration, the first lens is formed into a biconvex lens, the third lens is formed into a positive meniscus lens having a concave surface directed onto the object side, and the refractive index distribution of the refractive index distribution type second lens is defined by a predetermined conditional expression, whereby various kinds of aberration are made favorable even when used for reading out images at a magnification near 1:1, while achieving wider angle of view, higher performances, and compactness. An imaging lens for copying to be used at a magnification near 1:1 comprises the first lens L.sub.1 having a biconvex form, the second lens L.sub.2 having a biconcave form with a refractive index distribution along the optical axis direction, and the third lens L.sub.3 made of a positive meniscus lens having a concave surface directed onto the object side, whereas a stop i is disposed between the second lens L.sub.2 and the third lens L.sub.3. The refractive index of the second lens L.

Abstract: An optical system comprising a radial type gradient index lens element which has a negative refractive power of medium and a negative refractive power as a whole, and a radial type gradient index lens element which has a negative refractive power of medium and a negative refractive power as a whole; the optical system having favorable imaging performance: and an optical module using the optical system which is suited for stereoscopic photography and automatic focusing.

Abstract: In an image sensor having a photoelectric conversion element for receiving light, an illumination unit, and a lens array in which a plurality of gradient index lens elements for focusing light reflected by an original onto the photoelectric conversion element are arrayed, part of the peripheral portion of the lens of the gradient index lens element in the radius direction contains a light absorber for absorbing light having a predetermined wavelength other than the wavelength distribution of light emitted by the illumination unit.

Abstract: A planar solid immersion lens has flat surfaces on both the top and bottom. The planar structure is made to function as a solid immersion lens by including compensation for the refraction of light rays entering the top surface of the solid immersion lens other than normal to the top surface. Compensation can be provided by using a radial graded index lens material or by including on the top surface a surface relief diffraction grating. The planar solid immersion lens can be included in a slider or flying head used in an optical disk drive data recording system.

Abstract: A gradient index lens component composed of a single radial type gradient index lens element which has planar surfaces on both side and a positive refractive power and comprising an aperture stop which is disposed in the vicinity of an object side surface of the radial gradient index lens element for restricting a light bundle. And an image pickup apparatus composed by integrating the gradient index lens component with an image pickup device.

Abstract: A radial gradient contact lens is provided. The methodology described above allows the parameters of the lens and of the radial gradient profile to be chosen to improve the vision and the comfort of the wearer. The lens can be made thinner and the optical performance remains improved as the CL moves around in the eye. The improved vision leads to higher contrast when the iris of the eye is fully open as it is under low light level conditions. The use of an anamorphic lens consisting of an elliptical index profile for use in correcting astigmatism is described.

Abstract: GRIN lenses are made by an ion/exchange process. In order to make a GRIN lens whose gradient index varies slowly radially, a cylindrical glass rod of a sufficiently large diameter is immersed in a salty bath. The size of the lens may be reduced by grinding, polishing or chemically etching away a peripheral optically dispensable portion of the lens away from the axis of the lens so that the outer diameter of the lens is as small as 0.8 millimeters. When such a smaller lens is used in optical components such as circulators, switches, WDM's and isolators, such optical devices would also be reduced in size to fit within a limited space.

Abstract: A rod lens made of a transparent cylindrical medium having a refractive index distribution in the radial direction is used as a graded index lens. An object surface and an image surface are arranged on both sides of the rod lens. A first surface of the lens is a convex spherical surface, and a second surface of the lens is a planar surface, and the lens is arranged so that the convex spherical surface faces the object surface, and the planar surface faces an image surface. The equations1.0.ltoreq.R/r.sub.0 .ltoreq.1.6, andR/f.ltoreq.1.2are satisfied, wherein r.sub.0 is a radius of a portion of the rod lens that operates as a lens, measured from an optical axis of the lens, R is a curvature radius of the convex spherical surface, and f is a focal length of the rod lens. Thus, an object lens system with a large NA, that is smaller and lighter, while keeping the number of parts to a minimum, can be provided.

Abstract: An eyepiece system comprising a single radial type gradient index lens which has a refractive index varying dependently on distances from an optical axis in a radial direction and a negative power. This eyepiece system is composed of a small number of lenses, and has chromatic aberration, curvature of field, spherical aberration, etc. which are corrected favorably.

Abstract: A multi-pass optical filter using two identical filters provides narrower band filtering by double filtering an optical signal passing therethrough. Although passing a beam of light at an optical filter having a substantially thick optical thickness is known to have significant coupling losses due to angular misalignment of the output beam and the receiving optical fibre, it has been found that twice filtering in the conventional manner by serially coupling two same filters increases coupling losses. However, this invention provides a coupling arrangement wherein losses are significantly lessened by offsetting the axes of the lensed filters such that the beam exiting the first filter couples into the second filter as it would be reflected backward into the first filter.

Abstract: An objective lens system comprising a first lens unit composed of a cemented lens component which comprises a plurality of radial type gradient index lens elements having refractive indices varying dependently on distances as measured from an optical axis, wherein a gradient index lens element disposed on the object side has a concave surface on the object side. This objective lens system favorably corrects longitudinal chromatic aberration, offaxial aberrations and chromatic aberration, and is configured so as to facilitate the manufacture of the gradient index lens elements in practice.

Abstract: An optical imaging system includes a rod lens array, whose individual lenses have a refractive index distribution optimized for high resolving power, which can be expressed byn(r).sup.2 =n.sub.0.sup.2 .multidot.{1-(g.multidot.r).sup.2 +h.sub.4 .multidot.(g.multidot.r).sup.4 +h.sub.6 .multidot.(g.multidot.r).sup.6 }(Eq. 93)wherein r is a radial distance from an optical axis of said rod lenses, n.sub.0 is the refractive index at the optical axis of said rod lenses, and g, h.sub.4 and h.sub.6 are coefficients of the refractive index distribution. The refractive index distribution coefficients h.sub.4 and h.sub.6 are defined, using parameters a, b, c, and d, asc-d.ltoreq.h.sub.4 .ltoreq.c+d (Eq. 94){(h.sub.4 -c)/d}.sup.2 +[{h.sub.6 -(a.multidot.h.sub.4 +b)}/e].sup.2 .ltoreq.1. (Eq.

Abstract: An objective lens system consisting of a first lens unit having a negative refractive power and a second lens unit having a positive refractive power wherein the first lens unit or the second lens unit comprises at least one radial type gradient index lens element which has a refractive index distribution in a radial direction from an optical axis. This objective lens system favorably corrects chromatic aberration and other aberrations by adequately selecting a value expressing an Abbe's number and a refractive power of medium for the radial type gradient index lens element.

Abstract: A lens system which is composed of at least one homogeneous lens element and at least one radial type gradient index lens element, to be used as a combination lens system or an image pickup lens system, and configured to favorably correct chromatic aberration, etc. by selecting an adequate value for a coefficient representing an Abbe's number.

Abstract: A gradient index lens has a base lens and a resin layer. The resin layer is formed on a surface of the base lens. The resin layer has an aspherical surface. The base lens has a gradient index.

Abstract: An eyepiece lens comprising a single gradient-index lens having a positive refracting power, or comprising a radial gradient-index lens having a positive refracting power, and a field lens, wherein the following Eqs. are satisfied:1<.PHI..sub.m /.PHI.<1.5 (1).vertline..PHI..sub.S1 /<-.PHI..sub.S2 (2)-0.01<1/V.sub.1 <0.025 (3)where .PHI. is the refracting power of the radial gradient-index lens, .PHI..sub.m is the refracting power of a medium of the radial gradient-index lens, .PHI..sub.S1 is the refractive power of a surface located on the eye side of the radial gradient-index lens, .PHI..sub.S2 is the refracting power of a surface located on the object side of the radial gradient-index lens, and V.sub.1 is a coefficient of color dispersion of the medium of the radial gradient-index lens.