Abstract: A lens assembly includes, in order from an object side to an image side: a first lens; a first meniscus lens in optical communication with the first lens; a second meniscus lens in optical communication with the first meniscus lens; an aperture stop in optical communication with the second meniscus lens; a fourth lens in optical communication with the aperture stop; and a bi-convex lens in optical communication with the fourth lens. The lens assembly is a four group, five element, lens assembly that is constructed so that at least one of the lenses may be replaced without also requiring the other lenses in the assembly to be significantly changed, resulting in a “flexible” construction. The lens assembly may be adapted to provide a field of view of approximately 15 degrees; approximately 0% vignetting within the field of view; and a distortion of the image of less than approximately 1%. Multiple lens assemblies and detectors may be provided in a single housing.

Abstract: An image pickup lens includes: a first lens which is a positive lens having a positive refractive power; a second lens which is a negative lens having a negative refractive power; a third lens which is a positive lens; a fourth lens having at least one surface with an aspherical shape, wherein the first lens, the second lens, the third lens and the fourth lens are arranged from an object side of the image pickup lens in this order and the image pickup lens is designed using a predefined condition.

Abstract: The image forming optical system of the present invention comprises, in order from an object side, a first lens which is meniscus lens having positive refracting power and a concave surface directed toward an object side, an aperture stop, a second lens having positive refracting power and a convex surface directed toward the object side, a third lens which is meniscus lens having negative refracting power and a convex surface directed toward an image side, and a fourth lens having positive refracting power.

Abstract: A single-focus lens for an electronic still camera is formed of at least one meniscus lens element that is placed on the object side of a stop, with at least one surface of this meniscus lens element having a curvature such that light rays that pass through the stop are incident the surface substantially normally for all field angles, and an infrared-blocking coating is provided on the surface. Preferably, two specified conditions are satisfied to ensure that rays which are incident onto the coating are not adversely affected by the coating, thereby preventing color variations of objects which otherwise would occur.

Abstract: An image scanning lens includes four lens components that may include five lens elements as follows: a first lens element having negative refractive power and a meniscus shape with its convex surface on the object side, a second lens element having positive refractive power and a meniscus shape with its convex surface on the object side, a stop, a third biconcave lens element cemented to a fourth biconvex lens element, and a fifth lens element having negative refractive power and a meniscus shape with its concave surface on the object side. The image scanning lens satisfies certain conditions related to the focal lengths of the first, second, and third lens components of the image scanning lens and to the anomalous dispersion of the second lens element. An image scanning device, such as an image scanner, with an image pickup device, such as a CCD, uses the image scanning lens.

Abstract: A zoom lens system has four lens units, i.e., in order from an object side to an image side, a first lens unit of negative optical power, a second lens unit of positive optical power, a third lens unit of positive optical power, and a fourth lens unit of positive optical power. During zooming from a wide-angle end to a telephoto end, a space between the first lens unit and the second lens unit decreases, a space between the second lens unit and the third lens unit varies, and a space between the third lens unit and the fourth lens unit increases. Two negative lens elements constituting the first lens unit are made from high refractive index materials. Accordingly, a small-sized zoom lens system capable of obtaining a desired wide angle of field at the wide-angle end, a desired zoom ratio and high optical performance with a minimum number of lens elements can be provided.

Abstract: The image forming optical system comprises, in order from an object side, a first lens which is positive meniscus lens having a convex surface directed toward an object side, an aperture stop, a second lens which is positive meniscus lens having a convex surface directed toward an image side, a third lens which is positive meniscus lens having a convex surface directed toward an image side, and a fourth lens which is negative lens, wherein at least one of surfaces of the fourth lens is aspherical and the following condition is satisfied: ?2.0<?m/?p<0 where ?m represents the power of the fourth lens at the position of the maximum light height and ?p represents the power of the fourth lens at the position of the praxis. The third lens and the fourth lens are made of plastic material and the following condition is satisfied: 15.0<?3??4<40.0 where ?3 represents Abbe's number of the third lens and ?4 represents Abbe's number of the fourth lens.

Abstract: A zoom lens of a novel configuration suitable for a collapsible lens barrel is disclosed. More specifically, here is disclosed a zoom lens, comprising four lens units which are, in the order from an object side toward an image side, positive, negative, positive and positive in optical power, and performing zooming by varying distances between each lens units. In this zoom lens, the fourth lens unit has a positive lens element and a negative lens element, and satisfies the following conditional expression: ?n??p where ?n is the Abbe number of the negative lens element of the fourth lens unit, and ?p is the Abbe number of the positive lens element of the fourth lens unit.

Abstract: An image scanning lens includes four lens components, each of which may be a lens element. From the object side of the image scanning lens, the first lens component has positive refractive power and a meniscus shape with the convex surface on the object side, the second lens component has a biconcave shape, the third lens component has a biconvex shape, and the fourth lens component has negative refractive power and a concave surface on the object side and may be a meniscus lens or a biconcave lens component. The image scanning lens satisfies certain conditions related to the focal lengths of the first, second, and fourth lens components of the image scanning lens and to the relative partial dispersions of the lens elements. An image scanning device, such as an image scanner, with an image pickup device, such as a CCD, uses the image scanning lens.

Abstract: This specification discloses an image taking lens system which can quickly effect focusing from an infinity object to a short-distance object. The image taking lens system disclosed in the present specification has, in succession from an object side to an image side, a first lens unit, a second lens unit, a third lens unit and a fourth lens unit. In case of focusing from the infinity object to the short-distance object, the first lens unit is not moved, but the second lens unit is moved to the image side and the third lens unit is moved to the object side. The principal point interval between the first lens unit and the second lens unit is a negative value.

Abstract: A high zoom-ratio zoom lens system includes a positive first lens group, a negative second lens group, a positive third lens group, and a negative fourth lens group. Zooming is performed by moving each of the lens groups along the optical axis.

Abstract: In a photographic optical system disclosed in the present invention, there are provided a first focusing part for focusing while exposure is not performed on a light-sensitive surface and a second focusing part for focusing while exposure is performed on the light-sensitive surface, wherein the second focusing part correct the displacement in focal position during exposure.

Abstract: An image pickup lens has four lenses arranged in an order of a first lens, a second lens, a third lens and a fourth lens from an object side. The first lens has positive refractive power and has a convex surface facing toward an object side, the second lens has the positive refractive power, the third lens has negative refractive power and has a concave surface facing toward the object side to be formed in a meniscus shape, and the fourth lens has the positive or negative refractive power and has a convex surface facing toward the object side to be formed in the meniscus shape.

Abstract: The projection lens system is designed for the head mounted projective display (HMPD) system to provide a wide field of view up to seventy degrees. The lens is optimized from a double-Gauss lens composed of two singlet lenses, one diffractive optical element (DOE) lens, one aspheric lens and a stop surface in the middle of the lens said lens has a focal length as low as approximately 23.9 mm whereby it has a field of view (FOV) of up to approximately 70 degrees and more. The lens can be combined with an additional field lens whereby the resulting lens combination provides improved image quality and/or field of view beyond approximately 70 degrees.

Abstract: A single focus lens is composed of four lens components of negative, positive, negative and positive refractive power, respectively, in order from the object side. The first lens, in order from the object side, has a concave surface on the image side, and a stop is positioned between the first lens and the second lens. The second lens has a convex surface on the object side, the third lens has a concave surface on the object side, and the fourth lens has a convex, aspherical surface on the image side such that the refractive power of the fourth lens becomes weaker towards the edge of the lens. Specified conditions are preferably satisfied in order to provide favorable correction of aberrations.

Abstract: A pickup lens is provided in which various aberrations are satisfactorily corrected, which can be manufactured at low cost, and which has an optical length of 10 mm or less. This pickup lens is configured by arranging, in order from the object side, a first lens L1 with a meniscus shape with concave surface on the object side and having negative refractive power, an aperture diaphragm S, a second lens L2 with convex surfaces on both sides and having positive refractive power, a third lens L3 with concave surfaces on both sides and having negative refractive power, and a fourth lens L4 with convex surfaces on both sides and having positive refractive power; and with the following conditions satisfied.

Abstract: A lens system for a camera includes, in order from an object side, a distal lens having a convex surface and a concave surface, the convex surface being proximate the object side, a doublet lens in optical communication with the distal lens, and a bi-convex proximal lens in optical communication with the doublet lens. The doublet lens has a concave surface and a convex surface, with the convex surface of the doublet lens being proximate the convex surface of the distal lens.

Abstract: A taking lens system composed of four lens elements for forming an image on a solid-state sensor has, from the object side, a first lens element having a positive optical power, an aperture stop, a second lens element having a positive optical power, a third lens element having a negative optical power, and a fourth lens element having a negative optical power, and fulfills a prescribed condition.

Abstract: A lens for reading an original, comprises five lenses as a whole including two positive and two negative lenses, an aspherical surface provided on at least one surface of the five lenses, a construction of four lens groups for five lenses which include a cemented lens constructed by cementing one of the positive lenses and one of the negative lenses, an aperture stop disposed between a second and third lens groups, and the cemented lens disposed adjacent to the aperture stop.

Abstract: This specification discloses an image taking lens system which can quickly effect focusing from an infinity object to a short-distance object. The image taking lens system disclosed in the present specification has, in succession from an object side to an image side, a first lens unit, a second lens unit, a third lens unit and a fourth lens unit. In case of focusing from the infinity object to the short-distance object, the first lens unit is not moved, but the second lens unit is moved to the image side and the third lens unit is moved to the object side. The principal point interval between the first lens unit and the second lens unit is a negative value.

Abstract: A single focus lens is disclosed that is formed of only four lens components, which are arranged in positive, negative, positive and relatively weak positive or negative refractive power order from the object side, with a stop arranged between the first and second lens components. The third lens component has a convex surface on its image side, and the fourth lens component has a meniscus shape, is made of plastic, includes at least one aspheric surface, and is concave on its image side. The second lens component is formed of a single lens element, and various conditions are preferably satisfied so as to provide a compact lens having a short overall length while favorably correcting various aberrations.

Abstract: A single focus lens is composed of four lens components of negative, positive, negative and positive refractive power, respectively, in order from the object side. The first lens, in order from the object side, has a concave surface on the image side, and a stop is positioned between the first lens and the second lens. The second lens has a convex surface on the object side, the third lens has a concave surface on the object side, and the fourth lens has a convex, aspherical surface on the image side such that the refractive power of the fourth lens becomes weaker towards the edge of the lens. Specified conditions are preferably satisfied in order to provide favorable correction of aberrations.

Abstract: A reference lens for an interferometer is constructed so that light transmitted by a partially reflecting reference spherical surface may be converged, toward a focal point that coincides with the center of curvature of the reference spherical surface, and reflected from a subject spherical surface that also has its center of curvature at the focal point. Measurement of the shape of the subject spherical surface is possible based on the interference of two light beams, one reflected by the subject spherical surface and one reflected by the reference spherical surface. The reference lens, which may include five or six lens components or lens elements, includes a negative meniscus lens component, a positive lens group, and a positive lens component. Specified conditions are satisfied to provide a reference lens that has favorable correction of aberrations, is compact, and can measure the surface accuracy of a wide range of convex spherical surfaces.

Abstract: Projection exposure device and also projection objective with a lens arrangement which has at least one lens group of negative refractive power, this lens group comprising at least four lenses of negative refractive power, and a lens of positive refractive power being arranged after the third lens of negative refractive power in this lens group.

Abstract: A color image readout lens having four lens groups of positive, positive or negative, negative, and positive refractive power, respectively, in order from the object side. The first lens group is formed of a first lens element having a convex surface on the object side. The second lens group has a convex surface of the object side and is formed of a biconvex lens element that is cemented to a biconcave lens element. The third lens group is formed of a fourth lens element that is cemented to a fifth lens element, with the fifth lens element having positive refractive power and a convex surface on the image side. A fourth lens group is formed of a sixth lens element having a convex surface on the image side. Various conditions are satisfied in order to favorably correct the various aberrations.

Abstract: A wide-angle zoom lens system having a short optical total length not only at the wide-angle end but also at the telephoto end and a reduced telephoto ratio despite the fact that it has a high zoom ratio, with a view to achieving a reduction in size of cameras. The zoom lens system has a first lens unit G1 of positive refractive power, a second lens unit G2 of negative refractive power, a third lens unit G3 of positive refractive power, and a fourth lens unit G4 of negative refractive power. When the zoom lens system is zoomed from the wide-angle side to the telephoto side, each of the lens units moves toward the object side such that the space between the first lens unit G1 and the second lens unit G2 increases, whereas the space between the third lens unit G3 and the fourth lens unit G4 decreases.

Abstract: A real image type view finder comprising an objective optical system which has positive refractive power and forms an intermediate image, an image erecting optical system which erects the intermediate image and an eyepiece optical system which leads the intermediate image to an observer's eye, in which the objective optical system comprises a first positive lens unit, a second negative lens unit, a third negative lens unit and a fourth positive lens unit, moves the second lens unit and the third lens unit for a magnification change, has a vari-focal ratio on the order of 4, and has favorable optical performance over an entire zooming region.

Abstract: An attachment lens optical system for extending a focal length of a camera lens and balancing axial chromatic aberrations of the camera lens comprises, in order from the object side, a first lens group having a negative power single lens element, a second lens group including a cemented doublet of a biconcave lens element and a biconvex lens element, a positive power third lens group including three lens elements, and a negative power fourth lens group including a cemented doublet of two lens elements.

Abstract: An original reading lens for imaging the image information on the surface of an original on the surface of a sensor, includes an original reading lens having, in succession from the original side, a meniscus-shaped positive first lens having its convex surface facing the original side, a meniscus-shaped negative second lens having its convex surface facing the original side, a stop, a meniscus-shaped negative third lens having its convex surface facing the sensor side, and a meniscus-shaped positive fourth lens having its convex surface facing the sensor side, and the surface of a diffracting optical element disposed near the stop.

Abstract: A photographic lens comprising: a front lens group and a rear lens group that are arranged in order from the object side; wherein the front lens group comprises, in order from the object side, a first lens element which is a positive meniscus lens having a convex surface facing the object side, a second lens element which is a positive meniscus lens having a convex surface facing the object side, and a third lens element that is cemented to the second lens element, the third lens element being a negative meniscus lens having a convex surface facing the object side; wherein said rear lens group comprises, in order from the object side, a fourth lens element which is a positive meniscus lens having a convex surface facing the image side; a fifth lens element which is a negative meniscus lens having a concave surface facing the object side; a sixth lens element that is cemented to the fifth lens element, the sixth lens element being a positive meniscus lens having a convex surface facing the image side; and wher

Abstract: A lightweight and low cost replacement display for a conventional cathode-ray tube (CRT) display is provided that projects distortion free digital images directly without conversion to analog signals. The display does not exhibit cross-talk interference when a plurality of displays are placed adjacent one another, and does not present large gaps between adjacent displays. The display utilizes a digital micromirror device that projects a 1:1 bit mapped digital signal to a plurality of micromirrors that are switchable between an on and an off state and projects the image of light reflected from the "on" mirrors onto a direct view screen.

Abstract: An image pickup optical system comprising, in order from the object side, a first lens component which comprises a meniscus lens element having a convex surface on the object side and a positive refractive power, a second lens component which comprises a negative lens element, a third lens component which comprises a negative meniscus lens element having a convex surface on the object side and a biconvex lens element, and a fourth lens component which comprises a negative meniscus lens element having a convex surface on the image side. This optical system is configured so as to have a large aperture, reserve a sufficient amount of marginal rays, and correct coma and curvature of field by disposing a stop on the object side of the third lens component and defining a refractive power of a cemented surface of the third lens component within a certain range.

Abstract: A high-resolution objective for large-format photography has a pair of positive meniscuses flanking a stop area forming a lens aperture; and a respective negative cemented doublet on a side of each meniscus turned away from the stop area, the positive meniscuses being composed of glass having anomalous partial dispersion, a refractive index n.sub.e <1.63 and a dispersion or Abbe number .nu..sub.e >63, the cemented doublets each having a negative lens element and a positive lens element, the negative lens element being composed of a lead-free, arsenic-free and antimony-free glass with an anomalous dispersion, a refractive index n.sub.e >1.63 and an Abbe number .nu..sub.e <50.

Abstract: Successively from an object side, a stop, a biconvex lens, a biconcave lens, a biconvex lens, and a meniscus lens having a convex surface directed onto the image side are disposed, while the image-side surfaces of the second and third lenses are set to have a predetermined range of power, thereby favorably correcting various kinds of aberration, such as distortion in particular, while reducing the size of the whole lens system. Disposed successively from the object side are a stop i, a first lens L.sub.1 made of a biconvex lens, a second lens L.sub.2 made of a biconcave lens, a third lens L.sub.3 made of a biconvex lens, and a fourth lens L.sub.4 made of a meniscus lens having a convex surface directed onto the image side. These lenses satisfy the following conditional expressions :0.4<R.sub.5/ f<2.00.4<.vertline.R.sub.7 .vertline./f<2.2whereinR.sub.5 is a radius of curvature of the surface of the second lens on the image side;R.sub.

Abstract: A four-element lens configuration of positive, negative, positive, and negative satisfies predetermined conditional expressions, thereby correcting various kinds of aberration and achieving compactness and wider angle of view in a readout lens system. Further, without using an expensive glass material, higher image quality is attained. Successively from the object side, a first lens L.sub.1 made of a positive meniscus lens having a convex surface directed onto the object side, a second lens L.sub.2 made of a biconcave lens, a third lens L.sub.3 made of a biconvex lens, and a fourth lens L.sub.4 made of a negative meniscus lens having a convex surface directed onto the imaging surface side are arranged and configured so as to satisfy the following conditional expressions:-5.5<f.sub.12 /f<-2.8 (1)0.36<f.sub.3 /f<0.46 (2)-1.14<f.sub.2 /f.sub.3 <-0.8 (3)-8.8<f.sub.4 /D.sub.6 <-6.0 (4)0.23<R.sub.1 /f<0.

Abstract: Binary optics are used in an illumination system for a color projection display. In one embodiment a broad spectrum light source illuminates a multilevel optical phase element which disperses the broad spectrum light from the light source by diffraction. A display having a number of pixel elements, each capable of transmitting a predetermined spectral region, is positioned within the near field region of the multilevel optical phase element so as to receive the light dispersed by the multilevel phase element.

Abstract: Multi-spectral images are detected using a refractive objective lens system. Magnesium oxide (MgO) and calcium fluoride (CaF.sub.2) lenses are used to image scenes in both the visible and infra-red (IR) spectrums. The inventors have discovered that the combination of magnesium oxide, only recently made available in a pure crystal form, and calcium fluoride can be used to fabricate an objective lens for imaging objects in both the visible and infra-red spectrums. Moreover, the combination of magnesium oxide and calcium fluoride results in a super-achromatic condition across visible and infra-red spectrums. This chromatically-corrected spectral range includes wavelengths between 0.4 and 5.9 microns which covers medium-wave IR (MWIR), short-wave IR (SWIR), and the near-IR/visible windows. Combinations of MgO and CaF.sub.2 lenses are used in different compound objective lens designs including doublet, Petzval, inverted telephoto, and telephoto arrangements.

Abstract: A compact lens system has a predetermined focal length and comprises a plurality of lens elements and an internal aperture stop. The lens system is asymmetrical about the aperture stop. The plurality of lens elements define a field of view of at least 10 degrees. The plurality of lens elements include a front lens element, a rear lens element and at least one lens element located between the rear and the front lens elements. The rear lens element defines a rear vertex and a rear surface clear aperture with a predetermined diameter. The front lens element defines a front vertex and a front surface clear aperture with a predetermined diameter. The front and rear vertices are spaced apart less than 20% of the lens system's focal length. The front surface clear aperture diameter is within 10% of the rear surface clear aperture diameter.

Abstract: A taking lens for an underwater camera is constituted in the order from the side of a subject of a first lens group having no or slight refracting power, a second lens group having a positive refracting power, a third lens group having positive refracting power and a fourth lens group having negative refracting power. When focusing from the infinity to a closer distance, the first lens group is fixed to the image surface and the second and third lens groups are moved forward along the optical axis such that the distance between the second and third lens groups is changed.

Abstract: A projecting lens for projecting the image of an object onto a screen comprising, in the order from the screen side, a first lens group of a positive refractive power; a cemented second lens group of a positive refractive power; a third lens group of a negative refractive power; and a fourth lens group of a positive refractive power with a concave surface at the screen side; wherein each of the first and third lens group has at least an aspherical face, and the focal length f of the projecting lens, the focal length f1 of the first lens group and the focal length f3 of the third lens group satisfy conditions: 0<f/f1<0.25 and -0.1<f/f3<0.

Abstract: A great aperture zoom lens has, in succession from the object side, a first lens unit having positive refractive power, a second lens unit having negative refractive power, a third lens unit having positive refractive power, and a fourth lens unit having positive refractive power. The second lens unit has, in succession from the object side, a negative lens component, a negative lens component, a positive lens component and a negative lens component. In case of the magnification change from the wide angle end to the telephoto end, the first lens unit, the third lens unit and the fourth lens unit are moved toward the object side. The zoom lens satisfies various predetermined conditions.

Abstract: A 5.times. laser beam expander lens that is well-corrected for chromatic aberration can be used without refocussing over a wavelength range from 0.365 micron to 1.3 micron.

Abstract: A lens for an underwater camera is comprised of a first lens unit having no refractive power or having weak refractive power, a second lens unit comprising a forward unit having negative refractive power and a rearward unit having positive refractive power, and having weak refractive power, a third lens unit having positive refractive power, and a fourth lens unit having negative refractive power, the first lens unit being fixed relative to the image plane, the second lens unit and the third lens unit being axially moved together on the optical axis toward the object side relative to the fourth lens unit.

Abstract: A compound lens system specifically designed for use in a handy scanner of a computer system for photographing a printed object. The compound lens is capable of photographing the printed object up to a width of 128 mm, (5.04 in). The compound lens system encompasses four lenses which include a positive lens with a convex surface and a non-concave surface, two biconcave lenses, and a biconvex lens.

Abstract: A zoom lens is disclosed comprising, from front to rear, a first lens groups of positive power, a second lens group of negative power, a third lens group of positive power, and a fourth lens group, at least two of these four lens groups being moved to effect zooming and the second lens group being moved to effect focusing, and satisfying the following condition:-0.85<.beta.2T<-0.65where .beta.2T is the image magnification for an infinitely distant object of the second lens group in the telephoto end.

Abstract: A lens for reading an original at a reduced magnification has first to fourth lens groups sequentially arranged from an object side toward an image side, and a diaphragm arranged between the second and third lens groups. The first lens group are constructed by a joining lens having a positive focal length and is composed of positive and negative lenses. The second lens group are constructed by a joining lens having a positive focal length and is composed of a negative meniscus lens having a convex face on the object side and a positive meniscus lens having a convex face on the object side. The third lens group is constructed by a positive meniscus lens having a concave face on the object side. The fourth lens group is constructed by a joining lens composed of negative and positive lenses. A partial dispersion ratio .theta..sub.gF defined as (n.sub.g -n.sub.F)/(n.sub.F -n.sub.C) using refractive indexes n.sub.g, n.sub.F and n.sub.C of a lens material with respect to lines g, F and C, and an Abbe number .nu..

Abstract: An optical element (12) has aspherical (14) and binary grating (16) optical surfaces. In the preferred embodiment, the optical element (12) is a positive meniscus optical element made of germanium having a useful spectral bandpass in the infrared wavelength region. A telescope (100) includes a first positive meniscus optical element (102), having a convex aspherical surface (104) and a concave binary grating surface (106). A first negative meniscus optical element (107) having a concave binary grating surface (108) and a concave aspherical surface (110) is employed. Next is a positive power lens (112), followed by a second negative meniscus lens (118). In the preferred embodiment, the first negative meniscus optical element (107) and the positive power lens (112) are affixed to a common housing (124), which is removable from the telescope system. Removal of the housing (124) converts the telescope (100) system from a wide-field-of-view telescope (100) to a narrow-field-of-view telescope (40).

Abstract: An optical system particularly for a laser beam printer comprising a semiconductor laser, a collimating lens, a cylindrical lens having curvature in the sub-scanning cross section, a deflector and anamorphic scanning lens system concentrating the light on a scanning plane. The anamorphic scanning lens system may have one to four lenses but has one lens with a convex toric surface facing the scanning plane. The anamorphic scanning lens system has stronger power in the sub-scanning cross section than in the main scanning cross section.