Abstract: A zoom lens comprising a first lens unit of positive refractive power for focusing, a second unit of negative refractive power movable for zooming in a mono-direction throughout, a third unit of positive refractive power movable for zooming in the opposite mono-direction to that of movement of the second unit, and a fourth unit of positive refractive power having an image forming function which is held stationary during zooming, with a diaphragm being arranged in between the second and third units to be stationary.

Abstract: A gradient index lens array having improved stray light characteristics is enabled by coating the surfaces of the fibers comprising the array with a low transmittance, low viscosity material. The index of this material is matched to that of the fiber surface to prevent Fresnel reflection. The interstitial areas of the lens array comprises a light absorbing material. In another embodiment, stray light caused by light scattering at the end faces of the lens array is reduced by masking the end face with a mask having apertures overlying the fiber faces. The mask apertures have slightly smaller diameters to mask out the rough outer edge of the fibers.

Abstract: A projection lens system is disclosed which comprises in order from a screen side, a first lens unit having a positive focal length, a second lens unit having a negative focal length, a third lens unit having a positive focal length, a fourth lens unit having a positive focal length and a fifth lens unit having a negative focal length and a concave surface directed toward the screen side. The first and second lens units being made of plastic. At least one of lens surfaces of the first and second lens unit is aspherical. At least one of lens surfaces of the third and fourth lens units is aspherical. The fifth lens unit is made of plastic and at least one of lens surfaces of the fifth lens unit is aspherical.

Abstract: The color separating method for color photographing or printing is such that in case a color photosensitive material is used and the color separation is carried out by the color separating method, three kinds of filters consisting of three primary colors are caused to be sequentially or selectively disposed upon or removed from the optical axis of a light condensing unit in a lens group consisting of a large number of lenses of an optical system, and white light conducted from one end of the lens group is made to project the separated color component at the other end. The three filters are disposed upon a rotary filter support board which is selectively rotated by a control motor and a controller for the control motor which receives input control signals from a suitable source and outputs control signals to the control motor.

Abstract: A video projector lens system is provided, which comprises, from the screen side to the tube side, a first positive lens having a screen side convex surface, a second negative meniscus lens having a screen side convex surface, a third biconvex lens, and a fourth negative lens having a screen side concave surface. The first and second lenses are made of a plastic material for cancelling the temperature depending characteristic of one of the first and second lenses with the counterbalanced refractive power of the other thereof, wherein at least one aspheric surface is applied to the lens system. The third lens bearing a considerable part of the positive refractive power distributed in the whole lens system is made of a glass material for avoiding further temperature dependency.

Abstract: A gas zoom lens of the double Gauss type is disclosed. The lens, at a unity magnification setting, has cavities between the outer lens elements filled with a gas under a first pressure and a central cavity filled with the same gas at a second lower pressure. When the lens is moved to alternate magnification positions, its focal length is adjusted by changing the relative pressure, and hence the refractive index of the gas within the cavities, thereby adjusting the focal length of the lens for the particular magnification.

Abstract: A collimator lens meets conditions that:(i) at least the outgoing surface is spherical;(ii) the lens comprises at least an index-varying region in which the refractive index varies in the axial direction but does not vary in the direction perpendicular to the axial direction, and a constant index region all over which the refractive index is fixed;(iii) the point having the maximum refractive index n.sub.oo in the index-varying region is located at an apex of the profile of the lens;(iv) when the refractive index n(Z) on the optical axis at a distance Z from the apex is represent by n(Z)=n.sub.oo +n.sub.1 Z+n.sub.2 Z.sup.2, n.sub.oo is within the range of 1.50 to 1.77, n.sub.1 within the range of -0.14 to -0.02 mm.sup.-1 and n.sub.2 within the range of -0.03 to +0.03 mm.sup.-2 ; and(v) the inded-varying region is formed in the range of Z=0 to at least a depth d represented by an equationd=D.sup.2 /{4R(1+.sqroot.1-(D/2R).sup.

Abstract: A high zoom-ratio finite-distance lens with fixed object-to-image distance having arranged from the object side a first lens unit of positive focal length, a second lens unit of negative focal length and third and fourth lens units of positive focal length. The first, third and fourth lens units are moved relative to the second lens units. Conditions are set on the magnifications of the first, second and fourth lens units at the ends of the magnification range, on the relative displacements of the third and fourth lens units and on the location of the entrance pupil.

Abstract: A compact zoom lens comprising four components each movable axially to vary the focal length through a range of at least 2.5:1. There is a front negative, a positive component, a positive cemented doublet component and a rear negative component comprising three elements. A diaphragm is mounted with the first-mentioned positive component.

Abstract: A distributed index of refraction type lens is applied to a focusing lens suitable for a photographing lens to correct various aberrations. One distributed index of refraction type lens and a single-lens (including a bonded lens) of homogeneous medium are combined such that the distributed index of refraction type lens has an index of refraction distribution which continuously decreases as a light goes away from an optical axis, and has a thickness distribution which is smallest on the optical axis of the lens and increases as it goes away from the optical axis. Thus, the aberrations in the whole system can be corrected by the single distributed index of refraction type lens and a light and easy-to-manufacture focusing lens is provided.

Abstract: A low magnification projection objective lens for use in projection examination instrument. The projection objective lens comprises three lens units. The first unit is a converging lens unit composed of a positive lens component on the image side and a negative lens component on the object side, the second unit is a diverging lens unit composed of a negative lens component on the image side and a positive lens component on the object side and the third unit is a converging lens unit composed of a positive lens component.

Abstract: A lens system for focussing a divergent laser beam, particularly for converting the three dimensional amplitude and phase distribution of the highly divergent laser beam of a semiconductor laser into the amplitude and phase distribution of the fundamental mode coupleable into a monomode fiber is disclosed. The lens system comprises a front element in the form of a collecting aplanatic meniscus and one or more following refractive lenses for focussing the laser beam emerging from the front element. The refractive front face of the meniscus facing the object side aberration free point is designed such that it at least approximately has the form of a phase surface of the divergent laser beam emanating from a location at least close to the object side aberation free point which impinges the meniscus. The front face thereby becomes largely aberration free.

Abstract: A substantially solid transparent molded plastic body focuses light from an internal point to a point external to the body. The body has a center section with a surface having the curvature of a Cartesian Ovoid of revolution and a peripheral section. The peripheral section includes an inner refracting surface in the shape of a diverging truncated cone whose apex substantially coincides with the internal point and an outer reflecting surface in the shape of a polynomial curve of revolution. The slope of the outer surface causes it to reflect light rays between the refractory inner surface and the internal point. A light source such as an LED, or a photo-detector, may be immersed in the body at the internal point.

Abstract: A lens system for use with an optical disk comprises, in order from the side of a light source, a front group composed of a cemented lens made up of positive and negative lenses, and a rear group composed of a single positive lens or one positive and one negative lens. The lens system satisfying the following conditions:.nu..sub.30 >50, .nu..sub.- <35; (1)and.DELTA.N.sub.30 /.DELTA.N.sub.31 21 0.5, .DELTA.N.sub.31 >0 (2)where .nu..sub.30 is the Abbe number of a positvie lens, .nu..sub.31 is the Abbe number of a negative lens, .DELTA.N.sub.30 is the temperature coefficient of the refractive index of a positive lens, and .DELTA.N.sub.31 is the temperature coefficient of the refractive index of a negative lens.

Abstract: An apodizing filter is disclosed comprising two solid bodies of transparent material the first of which is struck by the incident light while the second receives the light from the first. The second body has a curve surface approaching the first body at a distance therefrom not greater than some wavelengths of the incident light. The plane tangent to the curve surface of the second body at the point of minimum distance from the first one forms with the direction of the incident light an angle greater than the limit angle of the total reflection related to the first body with respect to the medium in which the filter is sunk. The indexes of refraction of the two materials of which the two bodies are made are such that the light incidence on said tangent plane is lower than the limit angle of the total reflection. The combination is disclosed of the apoditic filter according to this invention with a mirror and an example is given of the filter application to a laser cavity.

Abstract: This invention relates to an anamorphic prism (11) for correcting an anisotropy of a radiation angle of a beam (14). The anamorphic prism (11) is constituted by a first prism (12) and a second prism (13) so that tha anamorphic prism (11) can have an achromatic structure. Refractive indexes and refractive index changes due to a wavelength fluctuation of the first and second prisms (12, 13), and an incident angle of the beam (14) to the first prism (12) can satisfy a predetermined relationship, and the beam (14) can be emerged from the second prism (13) at an exit angle of 0.degree.. The anamorphic prism of this invention can be applied to an optical head or the like using a semiconductor laser as a light source.

Abstract: A zoom lens system having magnification factors in the range of 20 to 47. The lens system of the present invention is particularly useful in micrographic reader/printers.

Abstract: A zoom lens including, from front to rear, a positive first component, a negative second component, a positive third component and a fourth component which is stationary during zooming. In some zoom lenses, a fifth component may be positioned behind the fourth component, in which, during zooming, the fourth component is movable and the fifth component is stationary. The separation between the first and second components and the separation between the second and third components varies to effect zooming. The third component is composed of, from front to rear, two positive lenses, a negative meniscus lens having a divergent cemented surface convex towards the front, and a positive lens with its rear surface having the stronger curvature. Minimization of bulk and size and an increase of the image magnification range of the zoom lens is achieved while preserving correction if aberrations.

Abstract: A zoom lens system having magnification factors in the range of 14 to 32. The lens system of the invention is particularly useful in micrographic reader/printers.

Abstract: The invention consists of a four-element telephoto projection lens for use in conventional overhead projectors, which lens assembly affords an extended projection distance from the lens to the projection screen while retaining the same back focus as conventional two-element projection lenses for overhead projectors.