Abstract: A wide-angle eyepiece lens having an angle of view greater than 60.degree. comprises, in order from the object end, a first lens group including a positive power meniscus lens element with a concave object side surface, an overall negative power second lens group including a doublet comprising, in order from the object side, a negative power lens element and a positive power lens element, and an overall positive power third lens group, and satisfies the following conditions:1.2<f1/f<3.53<-f2/f0.010<1/.upsilon.2N-1/.upsilon.2P1<.vertline.R3/f.vertline.wheref is the overall focal length of the eyepiece lens;f1 is the overall focal length of the first lens group;f2 is the overall focal length of the second lens group;.upsilon.2N is the Abbe number of the negative power lens element of the second lens group;.upsilon.2P is the Abbe number of the positive lens element of the second lens group;R3 is the curvature of radius of the foremost object side surface of the second lens group.

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

Abstract: An apparatus and method for transferring a pattern on a reticle onto a wafer includes a projection lens system having four groups of lens elements. The projection lens system satisfies the conditions: 0.3<.vertline.f.sub.G2 /L.vertline.<4.46, 1.8<.vertline.f.sub.G3 /L.vertline.<4.8, 0.05<.vertline.f.sub.G2 /f.sub.G3 .vertline.<0.25, 0.77<.vertline.f.sub.G1 /f.sub.G4 .vertline.<1.1, 0.17<f.sub.G4 /F<0.195, 0.14<f.sub.G1 /F<0.191, and having a numerical aperture equal to or greater than 0.60.

Abstract: An ocular optical system to be placed in front of a human eye forms a magnified virtual image of an original image displayed on a two-dimensional display element. The system has, in order from the eye: a positive first lens group including, in order from the eye, a meniscus first lens which has a concave surface directed toward the eye and a positive meniscus second lens which has a concave surface. A convex surface of the first lens directed toward the second lens and the concave surface of the second lens have the same radius of curvature and are bonded to each other. The system also has a second lens group including an aspherical third lens which has aspherical surfaces on both sides and has a negative on-axis refracting power; a third lens group including an aspherical fourth lens which has aspherical surfaces on both sides and has a positive on-axis refracting power; and a positive fourth lens group including, in order from the eye, a positive biconvex fifth lens and a negative biconcave sixth lens.

Abstract: An eyepiece system which is configured for observing an image formed by an objective lens system and comprises, in order from a side, of the objective lens system, a first lens element having at least one aspherical surface and a concave surface on the side of the objective lens system, at least one biconcave lens element and at least one positive lens element.

Abstract: A photographic lens apparatus secures a sufficiently large back focus while sufficiently distancing the exit pupil position from the image-forming surface. From the object side along an optical axis L, a stop, a first lens, a second lens, a third lens having a meniscus form, and a fourth lens group, in which a lens having a negative refractive power and a lens having a positive refractive power are cemented together to yield a positive refractive power, are successively disposed. Refractive index n.sub.1 and abbe number .nu..sub.1 of the first lens, abbe number .nu..sub.2 of the second lens, radius of curvature r.sub.7 of the surface facing the object and radius of curvature r.sub.8 of the surface facing the image in the third lens, abbe number .nu..sub.4 of the lens having the negative refractive power and abbe number .nu..sub.5 of the lens having the positive refractive power in the fourth lens group, focal length f.sub.

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 high-performance taking lens system suitable for a lens shutter type camera, which is capable of displaying superior optical performance as far as the edges of film image field with minimal deterioration of the performance despite a simple arrangement. The taking lens system has a front lens unit including at least one positive lens (G1) and at least one negative lens (G2) whose image-side surface has a higher curvature than that of the object-side surface thereof, and a rear lens unit disposed behind the front lens unit and including a doublet (G3) which consists of one positive lens and one negative lens and which has a positive refractive power, and a positive lens (G4). The lens surface of the doublet (G3) that is the closest to the image side is concave toward the image side. The intermediate lens surface of the doublet (G3) is convex toward the image side. The negative lens (G2) is preferably a meniscus negative lens having a concave surface directed toward the image side.

Abstract: A zoom lens having a four-unit lens construction with positive, negative, positive, and positive refractive powers. In an embodiment, the second lens unit is moved toward the image side during the magnification change from the wide angle end to the telephoto end, and the third lens unit is moved in a direction substantially orthogonal to the optical axis to effect image stabilization. The zoom lens satisfies the condition that .DELTA.Y=f.sub.4 /f.sub.3 .multidot..DELTA.S. In another embodiment, the first, third, and fourth lens units are moved toward the object side during the magnification change from the wide angle end to the telephoto end, and the second lens unit is moved in a direction substantially orthogonal to the optical axis to effect image stabilization. The zoom lens satisfies the condition that .DELTA.Y=(1-.beta..sub.2).multidot..beta..sub.34 .multidot..DELTA.S.

Abstract: Binoculars designed to provide a large aided static field of view are provided. The binoculars are characterized by S/D ratios of above 2.8, where S is the binoculars' aided static field of view calculated by multiplying the binoculars' magnifying power by the binoculars' semi field of view in object space and D is given by tan.sup.-1 [(R.sub.ex +1.5)/13], where R.sub.ex is the radius of the binoculars exit pupil the following expression in which R.sub.ex and the constants 1.5 and 13 are in milliliters. As a result of the increased S/D ratio, the binoculars of the invention minimize the sensation of tunnel vision which normally occurs when binoculars are used and reduce the user's apprehension of missing activities in his or her peripheral vision. In certain embodiments, a movable field lens unit is employed to provide variable power and a negative corrector lens unit is employed for aberration correction and to minimize the size of the binoculars.

Abstract: A microscope objective lens, sequentially from an object-side, comprises a first lens group constructed of a positive lens element, a second lens group constructed of a negative lens element, and a third lens group constructed of cemented lens elements consisting of a negative lens element and a positive lens element and exhibiting a positive refracting power on the whole. Further, the microscope objective lens system satisfies the following conditions:1.5<f/f.sub.1 <1.9-3.8<f/f.sub.2 <3.12.0<f/f.sub.3 <2.70.9<(d.sub.2 +d.sub.3 +d.sub.4 +d.sub.5)/f.sub.1 <1.215<n.sub.1 .multidot.f/d.sub.150<n.sub.2 .multidot.f/d.sub.3wheref : the focal length of the whole system,f.sub.1 : the focal length of the first lens group,f.sub.2 : the focal length of the second lens group,f.sub.3 : the focal length of the third lens group,d.sub.1 : the central thickness of the positive lens element in the first lens group,d.sub.

Abstract: A zoom finder of a real image type has an objective lens having positive refracting power and an eyepiece having positive refracting power. The objective lens is constructed by first, second, third and fourth lens groups sequentially arranged from an object side. The first lens group has positive refracting power. The second lens group has negative refracting power. The third lens group has positive refracting power. The fourth lens group has positive refracting power. The zoom finder is constructed such that a real image is focused and formed by the objective lens between the fourth lens group and the eyepiece and is observed through the eyepiece. A magnification of the zoom finder is increased by moving the second lens group from the object side to an eyepiece side. A change in diopter caused by this increase in magnification is corrected by moving the fourth lens group. In accordance with the above structure, an entire length of the zoom finder is short and is not changed in a zooming operation.

Abstract: Binoculars designed to provide a large aided static field of view are provided. The binoculars are characterized by S/D ratios of above 2.8, where S is the binoculars' aided static field of view calculated by multiplying the binoculars' magnifying power by the binoculars' semi field of view in object space and D is given by tan.sup.-1 [(R.sub.ex +1.5)/13], where R.sub.ex is the radius of the binoculars' exit pupil and where R.sub.ex and the constants 1.5 and 13 are measured in millimeters. As a result of the increased S/D ratio, the binoculars of the invention minimize the sensation of tunnel vision which normally occurs when binoculars are used and reduce the user's apprehension of missing activities in his or her peripheral vision. In certain embodiments, a movable field lens unit is employed to provide variable power and a negative corrector lens unit is employed for aberration correction and to minimize the size of the binoculars. The binoculars are suitable for mass production and general consumer use.

Abstract: A zoom lens includes, in the order from the object side, a first lens unit of positive refractive power, a second lens unit of negative refractive power, a third lens unit of positive refractive power and a fourth lens unit of positive refractive power. The first and third lens units are stationary. The second lens unit is moved in one direction to vary the magnification. The fourth lens unit is moved so as to compensate for the shift of an image plane resulting from the variation of the magnification, and focusing is performed by moving the fourth lens unit. The third lens unit has a bi-convex lens and a negative meniscus lens having a strong concave surface facing the object side, and the fourth lens unit has a negative meniscus lens having a strong concave surface facing the image side, a bi-convex lens and a positive lens having a strong convex surface facing the object side.

Abstract: A zoom lens comprises a first lens unit having a positive refractive power, a second lens group having a negative refractive power, an iris and a third lens unit having a positive refractive power, arranged in this sequence as viewed from an object. The third lens unit comprises a lens unit 3a and a lens unit 3b arranged in this sequence as viewed from the object, with a large air gap therebetween. Zooming from a short focal length end to a long focal length end is effected by moving the second lens group from a unit side to a image side and moving the first lens unit and the third lens unit to depict convex loci toward the object. The zoom lens meets the condition of-0.3<HF.sub.3 /f.sub.3 <0.20.5<l.sub.3 /f.sub.3 <1.5whereHF.sub.3 is a distance between an apex of a lens of the third lens group facing the object and a front principal point of the third lens unit,f.sub.3 is a focal length of the third lens unit, andl.sub.3 is an air gap between the lens unit 3a and the lens unit 3b.

Abstract: A zoom lens comprises sequentially from a side of an object: a fixed first lens group constituted by a convex lens, a double convex lens and a meniscus convex lens; a movable second lens group constituted by a meniscus convex lens, a double concave lens and a convex lens; a fixed third lens group constituted by a single lens having at least one aspherical surface; and a movable fourth lens group constituted by a concave lens and two convex lenses at least one of which has at least one aspherical surface.

Abstract: The invention relates to a compact, lightweight and inexpensive zoom lens system which, even when used with a small image sensor, allow the convex lenses to have a sufficient peripheral thickness and the concave lenses to have a sufficient central thickness and which comprises, in order from the object side, a first unit having a positive refracting power, a second unit having a negative and being movable during zooming, a third unit having a positive refracting power and remaining fixed in place and a fourth unit having a positive refracting power and being movable during zooming and focusing; said third unit comprising, in order from the object side, two lenses in all, one being a positive lens having a strong curvature on the object side and the other a negative lens having a strong curvature on the image side, and said third and fourth units each having at least one aspherical surface whose refracting power decreases as it is spaced away from the optical axis and conforming to the following conditions (1)

Abstract: A finder optical system including an objective having a positive refractive power, an image erecting optical member for erecting an image formed by the objective, and an eyepiece for allowing observation of the image formed by the objective and erected by the image erecting optical member. The objective consists of a first positive lens component and a second negative lens component, or a single lens having a convex surface on the object side. This finder optical system has a simple composition, a compact external design and a relatively wide field angle.

Abstract: In one embodiment, a three-element biocular eyepiece system 40 having a first optical element 42 with at least one diffractive surface 44, a second optical element 48 having a refracting convex surface 50 and a refracting concave surface b 52 is provided. A third optical element 54 having a refracting convex surface 56 and a refracting convex surface 58 is also employed. In another embodiment, a four-element biocular system 60 is disclosed as having an optical element 62 having a refracting concave surface 64 and a refracting convex surface 66, a refractive-diffractive hybrid optical element 68 having a diffractive surface 70 and a refracting convex surface 72, an optical element 74 having a refracting convex surface 76 and a refracting concave surface 78, and an optical element 80 having a refracting concave surface 82 and a refracting convex surface 84. The diffractive surfaces 44 and 70 have a kinoform profile 102 a-d or approximated kinoform profiles 112a-d and 122a-d.