Abstract: An optical lens system is provided having the capability of selectively varying the peripheral field curvature to improve focusing for nonplanar objects and for special photographic effects. The lens system can include in sequence, a first lens group of positive refractive power, a second lens group of negative refractive power and a third lens group of positive refractive power. The specific refractive power of the first and second lens group are designed so that the optical ray traces from an object on the optical axis at infinity will run approximately parallel with the optical axis in the space between the second and third lens groups. The first and second lens groups being movable as a unit relative to the third lens group to change the field curvature without varying the back focal distance of the lens system.

Abstract: A seven-member microscope objective having a numerical aperture of 0.55 providing a magnification of substantially 40X in combination with a telescope objective as described in U.S. Pat. No. 3,355,234 is disclosed.

Abstract: A zoom lens system having a range in the order of 1:9 with a relative aperture of 1:1.4, including a variable afocal front attachment and a basic objective which is designed to improve the Petzval sum with front and rear groups each consisting of three lens elements of positive, positive and negative powers in this order from the front by fulfilling the following relationships with its individual focal length Fr: ##EQU1## wherein Ff is the focal length of the front group; r4 is the radius of curvature of the rear surface of the second positive lens in the front group; r5 is the radius of curvature of the front surface of the negative lens in the front group; r8 and r10 are the radii of curvature of the rear surfaces of the first and second positive lenses in the rear group respectively; and r11 is the radius of curvature of the front surface of the negative lens in the rear group.

Abstract: An objective lens system for microscopes consisting of a front lens group comprising a positive lens component and a meniscus lens component having a concave surface on the image side, and a rear lens group comprising at least a meniscus cemented lens component, a positive lens component and at least one cemented three-element lens component. Said objective lens system is so designed as to have a large numerical aperture, secondary spectrum sufficiently minimized, a long working distance and curvature of field, coma etc. favorably corrected over a wide range of visual field.

Abstract: Apparatus is provided for testing subjects for fixation disparity. The apparatus includes a first sheet-like element having an opening therein which is spaced from the subject being tested. This opening defines the periphery of a target which is dimensioned to represent a fusion stimulus to the subject. Within the opening there are displayed a sequence of paired first and second discrete, parallel target elements which are mutually spaced and fixed a predetermined distance from each other along the parallel lengthwise extends thereof. A sequence of these element pairs are positioned in regularly spaced order about a movable carrier and presented sequentially at the opening in the course of testing. The angular subtense represented by the spacing of the elements is indicated upon the carrier and when the subject perceives that the elements are mutually aligned, a recordation of angular subtense is made and utilized for diagnostic purposes.

Abstract: A refractor optical system having a new series of spherical and cylinder lenses substantially eliminates the irregular occurrence of additive errors when lenses spaced from the reference plane are used or more than two lenses are combined and permits correction for the significant additive errors by non-additive lens selection.

Abstract: An optical system in which at least one of the elements is made from so-called gradient glass having a radial difference in refractive index. The element having this radial difference may be either a lens with at least one curved surface, or a plane-parallel plate. The radial variation in refractive index varies in accordance with a formula which is given.

Abstract: A semi-wide angle objective lens in accordance with the present invention comprises five groups of six lens elements including a front group and a rear group in which the front group has a first group which includes a single positive meniscus lens L.sub.1 with its convex surface directed toward the object side, a second group which includes a single negative meniscus lens L.sub.2 with its convex surface directed toward the object side, and a third group which includes a single positive meniscus lens L.sub.3 with its convex surface directed toward the object side; and in which the rear group has a fourth group which includes both a negative lens L.sub.4 with its front concave surface having a large curvature directed toward the object side and a positive lens L.sub.5 with its rear convex surface having a large curvature directed toward an image side with the fourth group lenses cemented together or arranged with an extremely small air space therebetween, and a fifth group which includes a positive lens L.sub.

Abstract: A photographic lens system of modified Gauss type comprising a first, second, third fourth and fifth lens components in which the first and second lens components are positive meniscus lenses arranged convex toward the object side, the third lens component is a negative meniscus lens arranged convex toward the object side, the fourth lens component is a negative cemented meniscus doublet comprising a biconcave lens and biconvex lens, the fifth lens component is a biconvex lens, the photographic lens system being compact and light in weight and having a long back focal length and aberrations corrected favorably.

Abstract: A large-aperture wide-angle lens system for photographic cameras with corrected flare due to coma of marginal pencil comprising a flare stop arranged in the vicinity of an intersecting point between the maximum aperture ray of paraxial pencil and the outermost ray of offaxial pencil directing to the marginal portion of image.

Abstract: A five component Ernostar type telephoto lens having a focal length in the intermediate order up to 135 m/m with a telephoto effect down to 0.84 but with limitation of zonal spherical aberration to a minimum is disclosed. The lens system comprises, from front to rear, a biconvex lens having a far larger front curvature than that of a rear surface thereof, a forwardly convex positive meniscus lens, a negative doublet composed of a forwardly concave front positive meniscus lens element and a rear biconcave lens element and followed, after a large axial air separation, by a negative meniscus lens of forward concavity, and a biconvex lens. The system fulfills the following requirements: ##EQU1##0.3F<.vertline.R6.vertline.<0.5Fwherein R6<0where F is the focal length of the entire system; .phi.1 is the focal length of the first biconvex lens; .phi.4,5 is the composite focal length of the last two lenses; and R6 is the radius of curvature of the cemented surface in the doublet.

Abstract: A reproducing objective for video disks comprising a first, second, third and fourth lenses in which the first lens is a biconvex lens, the second lens is a negative meniscus lens, and the third and fourth lenses are positive lenses and for which the working distance is large, flatness of image is high, resolving power is high and weight is extremely light.

Abstract: A retrofocus wide angle objective having an angle of view of at least 82.degree. with a relative aperture of 1:2.8 and whose back focal distance is made longer than 1.4 times the focal length of the entire system. The objective comprises, from front to rear, a first lens of positive power in a forwardly convex meniscus form, a second negative meniscus lens, a third positive lens, a fourth negative lens, a fifth biconvex lens, a diaphragm, a sixth biconvex lens, a seventh biconcave lens, and eighth and ninth positive lenses. In such retrofocus objective with the positive meniscus lens arranged at the front, while the angle of view is maintained increased, the lens system is reduced in dimensions and is properly corrected in particular for distortion and astigmatism.

Abstract: A method of focussing in a photographic lens system consisting of a front convergent lens group and a rear divergent lens group, the front lens group comprising a first lens component having a positive refracting power, a second lens component having a negative refracting power and a third lens component having a positive refracting power, the improvement being that the third lens component is caused to move within the photographic lens system.

Abstract: This specification discloses a beam shaping optical system for treating the diverging beam emitted from the exit surface of a semiconductor laser. The beam from the semiconductor laser has different angles of divergence and different origins of divergence in directions orthogonal to each other. Such a beam may be collimated or efficiently treated into a circular spot light by the beam shaping optical system.

Abstract: An inverted telephoto type wide angle lens system comprises, in order from the object side, a negative meniscus lens having its convex surface facing the object side, a first positive lens, a negative lens, a second positive lens and a third positive lens. The lens system satisfies certain conditions.

Abstract: A lens system for micro film which provides high resolution over a wide range with an ultraviolet ray, and has transmittance sufficient for said ray and a long working distance on the image side. Said lens system comprises a first negative cemented doublet component, a second positive lens component, a third positive lens component, a fourth positive lens component, a fifth positive lens component, a sixth negative cemented doublet component, a seventh negative meniscus lens component, an eighth cemented meniscus lens component and a ninth positive meniscus lens component.

Abstract: Apparatus for viewing an eye fundus through a contact lens has an illuminating element that illuminates the fundus through the sclera. The illuminating element includes at least one fiber optic bundle with an exit facet for placement contiguous with the sclera, generally through whatever thickness of occular conjunctiva is present. The apparatus also has an optical mask system which masks the image of the fundus portion most intensely illuminated by the fiber optic exit facet to control over-illumination of that fundus portion.

Abstract: A photo eyepiece for microscopes comprising a front lens group consisting of a first positive meniscus lens component, and a rear lens group consisting of a second positive single or cemented lens component, a third negative lens component and a fourth positive single or cemented lens component. Astigmatism, curvature of field, etc. are favorably corrected in said photo eyepiece so that it can form good images over a wide visual field of micrography.

Abstract: A zoom lens having a focal length range of about 1:9.5 with a relative aperture of 1:1.4 and whose minimum focal length is made shorter than has heretofore been possible to correspond to an image angle of 56.degree. or more, while good stability of aberration correction is maintained throughout the extended zooming range at the increased relative aperture with limitation of the overall dimensions to a minimum. The lens is suitable for cine cameras of small size and includes a positive first group of four lens elements movable for focusing, negative second and negative third groups axially movable to effect zooming, a positive fourth group acting in afocal manner, and a positive fifth group having an image forming function, the first, fourth and fifth groups being stationary during zooming.