Abstract: Eyepiece variable focal length optics comprise, in order from the objective optics, a negative lens group, a positive lens group, a positive lens group and a positive lens group; during variable focal length from longest focal length side to shortest focal length side, the first lens group moves monotonically toward the objective optics, the second lens group moves monotonically toward the eye, and the third lens group moves toward the eye in such a way that the distance from the second lens group is first increased and then decreased; the fourth lens group is stationary.

Abstract: The invention relates to a microscope eyepiece with theoretically reduced astigmatism in a compensating optical system. The inventive eyepiece has 10× magnification, a sight field (SFZ)≦25 and a Petzval sum (SP) of 0.014≦SP≦0.021. Said eyepiece comprises a special field lens placed in front of a field stop and a negative lens in the eye lens section placed behind said field stop. The inventive field lens is embodied in the form of a simple, thick, positively diffracting meniscus which is convex in relation to the field stop and provided with the following field lens factor: 0.95≦beta′≦1.05. The eye lens section can be displaced in relation to the field stop to enable diotropic adjustment. Special, advantageous embodiments of the field lens and examples of embodiments of the microscope eyepiece, complete with structural data, are described.

Abstract: An eyepiece lens assembly including a collecting lens, glass spherical cemented doublet, a plastic singlet, and a glass spherical singlet. The assembly provides over 30 degrees extended field of view, a greater than 30 mm eye relief, under 5% distortion, a substantially telecentric focal plane, and weighing under 6 ounces.

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: There is provided an eyepiece lens system for viewing an image formed by an objective lens system. The eyepiece lens system includes a first refraction lens having a positive power, a second refraction lens having a positive power and at least one diffraction lens having a phase grating structure. The first and second lenses are arranged on an eye side with respect to a plane on which the image is formed.

Abstract: A real-image finder optical system includes a positive objective optical system, an image-erecting optical system and an eyepiece optical system, in this order from the object. The image-erecting optical system includes a pattern display surface having a reflective pattern, and a half mirror surface, transmitting a portion of the light rays incident from the object, and again reflecting the light rays having been reflected from the pattern display surface. The real-image finder optical system forms a real image of the object formed through the objective optical system and a virtual image of a pattern on the pattern display surface formed by an optical system including the half mirror surface so that an operator can simultaneously view both the real image of the object and the virtual image of the pattern through the eyepiece optical system; and the real-image finder optical system satisfies the condition:0<d.sub.1 /f.sub.e .ltoreq.0.1 (1)wherein d.sub.

Abstract: Wide-angle eyepiece lenses for a microscope are disclosed. A representative lens comprises, from the object side to the eye side, a first lens group with positive refractive power, a second lens group with a concave surface facing the object side and a surface (closest to the object side) contacting air, and a third lens group with positive refractive power and at least one surface contacting air. One or both of the surface of the second lens group closest to the object side and the air-contacting surface of the third lens group is aspherical.

Abstract: An eyepiece optical system includes the first lens group constituted by a negative single meniscus lens element having a convex surface on the side of a user's eye, and the second lens group having positive power as a whole, in this order from the object, whereby an intermediate image formed by an objective optical system is positioned between the first lens group and the second lens group. The second lens group includes a positive single meniscus lens element having a convex surface on the side of a user's eye, and a cemented sub-lens group having positive power as a whole. The cemented sub-lens group includes a positive lens element and a negative lens element. Furthermore, the eyepiece optical system satisfies the following conditions:-15<f.sub.1 /f.sub.1 <-3.5 (1)-10<f.sub.1 /f.sub.2 <-3.0 (2)whereinf.sub.1 designates the focal length of the first lens group;f.sub.2 designates the focal length of the second lens group; andf.sub.e designates the focal length of the entire lens system.

Abstract: An eyepiece system comprising, in order from the object side, a first lens unit having a negative refractive power and a second lens unit having a positive refractive power, and configured to locate an intermediate image formed by an objective lens system between the first lens unit and the second lens unit: the first lens unit being a negative lens unit having an object side surface which is convex toward the object side. This eyepiece system has a wide visual field and a long eye relief, and corrects aberrations favorably even at marginal portions of the visual field.

Abstract: A wide-field eyepiece, formed of at least four lens groups and five lens elements, is disclosed which satisfies predetermined conditional expressions, so as to provide an eyepiece having an angle of view of at least 65 degrees with less than 6% distortion. The wide-field eyepiece is formed of, in order from the side of an image position 1 formed by an objective lens (not illustrated): a first lens group G.sub.1 of negative refractive power that includes a first lens element L.sub.1 having a concave surface on both sides, a second lens group G.sub.2 of positive refractive power that includes a second lens element L.sub.2 having a convex surface on the side of an observer's eye position, a third lens group G.sub.3 of positive refractive power wherein a lens element surface thereof has a convex surface on both sides and is cemented to a negative lens element having a concave surface on the side nearest the image 1 formed by the objective lens; and a fourth lens group G.sub.

Abstract: An eyepiece including a positive first lens element, a negative second lens element, a positive third lens element and a positive fourth lens element is provided. The first, second, third, and fourth lens elements are spaced from one another and arranged in this order from an object side. At least one of the four lens elements is a plastic lens with at least one aspherical surface satisfying the relationships defined by;d.sup.2 x/dh.sup.2 .ltoreq.{c/(1-0.sub.+ 5c.sup.2 h.sup.2).sup.3/2 }: when c >0; andd.sup.2 x/dh.sup.2 .gtoreq.{(c/1-0.sub.+ 5c.sup.2 h.sup.2).sup.3/2 }): when c<0;wherein"c" represents paraxial curvature;"x" represents sag amount; and,"h" represents a height from an optical axis.

Abstract: An eyepiece lens is disclosed, in which the total number of constituent lenses is reduced but good optical performance is obtained by setting forth proper rules of design for optical parameters.

Abstract: An eyepiece optical system for projecting a plane image on a two-dimensional display element onto an eyeball as an extended virtual image, comprises a first group of lenses G1 including a positive meniscus lens L1 having a concave face toward the eyeball, a both-face aspeherical lens L2 and a both-face aspherical lens L3 having both convex faces in the vicinity of center and positive paraxial refractive power; and a second group of lenses G2 including a both-face aspherical lens L4 having both concave faces in the vicinity of center and negative paraxial refractive power, the first and second groups of lenses being arranged in order from the side of the eyeball. An eyepiece image display device uses such an eyepiece optical system.

Abstract: A viewfinder optical system has a relay lens system and an eyepiece optical system. The relay lens system refocuses a primary image as a secondary image. The relay lens system consists of a single lens element which has a surface having optical power of diffraction. The eyepiece optical system magnifies the secondary image and has a surface having optical power of diffraction.

Abstract: An eyepiece lens is disclosed, in which the total number of constituent lenses is reduced but good optical performance is obtained by setting forth proper rules of design for optical parameters.

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 includes a biconvex lens, a bonded negative meniscus lens including a negative lens with a concave surface which faces the object, and a positive lens having a convex surface which faces an eyepoint. A biconvex lens and a positive lens having a convex surface which faces the object are also provided. Certain prescribed conditional equations are met by the eyepiece.

Abstract: In a non-flexible endoscope consisting of an insertion section and an eyepiece section which are separable from each other, an optical system configured so as to correct chromatic aberration produced by an observation optical system disposed in the insertion section with an eyepiece optical system disposed in the eyepiece section. The optical system according to the present invention selects a simple composition for the observation optical system so that it is manufacturable at a low cost and disposable, and is configured so as to have favorable optical performance as a whole by correcting chromatic aberration produced by the observation optical system with the eyepiece optical system.

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: An optical eyepiece assembly for providing a sixty degree field of view cbility to an image intensifier. The assembly includes first and second air-spaced lens doublets, a first lens, filter element, and second lens.

Abstract: An eyepiece lens suitable for use in microscopes, binoculars, and the like is disclosed. The eyepiece lens provides a large eye relief of more than 80 percent of the focal length of the eyepiece lens in an apparent field of view of more than 60 degrees, preferably more than 70 degrees, while favorably correcting various aberrations such as distortion up to the perimeter of the apparent field of view of the eyepiece lens. The eyepiece lens is disposed on the eye side of a real image plane of an objective lens with which the eyepiece lens is used, and comprises, in order from the objective side, a first cemented lens L.sub.1, preferably a doublet, a second cemented lens L.sub.2, preferably a doublet, a first positive lens element L.sub.3, and a second positive lens element L.sub.4. The eyepiece lens preferably satisfies a number of quantitative conditions.

Abstract: An eyepiece lens has an apparent field of no less than 40.degree., and minimizes eye relief error. The eye relief includes a distance between a lens surface closest to an eye point side in the eyepiece lens and an eye point. The eyepiece lens comprises an assembly of lens groups including, from the eye point, a first lens group G.sub.1 that includes one positive lens component, a second lens group G.sub.2 with positive refracting power that includes a cemented lens having a negative lens component and a positive lens component, a third lens group G.sub.3 with positive refracting power that includes a cemented lens having a positive lens component and a negative lens component, and a fourth lens group G.sub.4 that includes one negative lens component. The assembly of lenses is configured such that 1.4.ltoreq..vertline.R7/R4.vertline.

Abstract: An eyepiece lens is disclosed that corrects aberrations over a wide apparent field of view, and has a short overall length and sufficiently long eye relief (typically at least 150% of overall focal length F). The eyepiece lens comprises, in order from the objective lens side, first and second lens groups having negative and positive refractive power, respectively, with a field stop situated therebetween. The first lens group comprises a cemented negative lens including two lens elements cemented together. The second lens group comprises, in order from the objective lens side, a positive meniscus lens element having a concave surface oriented objectivewise; a cemented lens comprising two lens elements cemented together and in which the most objectivewise lens surface is a concave surface oriented objectivewise; and a lens subgroup having positive refractive power and comprising a positive meniscus lens element having a concave surface oriented eyewise. The eyepiece lens satisfies at least the conditions: -4.5.

Abstract: An objective lens system for an endoscope comprises from the subject end to the image end a meniscus lens element of negative optical power having a concave image side surface, a plano-convex lens element of positive optical power having a convex subject side surface, an aperture element, a plano-convex lens element of positive optical power having a convex image side surface and a biconvex lens element of positive optical power.

Abstract: An eyepiece lens comprising, from front to rear, a first lens unit of positive refractive power having a negative lens and a positive lens, a second lens unit of positive refractive power and a third lens unit of positive refractive power, wherein at least one of the lens surfaces in the first lens unit to the third lens unit is made aspherical, and wherein the apparent field of view covers an angle of about 50 degrees, the eye relief is elongated, and the field curvature is corrected well.

Abstract: An eyepiece has an apparent visual angle of 40.degree. or more, and is constituted by, in the following order from the eyepoint side, a first lens group including a cemented lens of negative and positive lens components and having a positive refractive power, a second lens group including a single positive lens component, a third lens group including a cemented lens of positive and negative lens components and having a positive refracting power, and a fourth lens group including a single negative lens component. At least one surface in these lens groups is an aspherical surface, and the fourth-order aspherical surface coefficient of the aspherical surface satisfies .vertline.C.sub.4 .vertline..ltoreq.1.times.10.sup.-3.

Abstract: An optical system for a compound camera includes an equivalent image plane provided at a position substantially optically equivalent to an image plane of the photographing lens system. A condenser lens is provided proximate to the equivalent image plane and a relay lens system is provided behind the condenser lens to form an image of the photographing lens system on an image pickup device. The relay lens system satisfies the requirements defined by -0.1<P<0.09, and S3<0, where P designates the Petzval sum of the whole relay lens system when the focal length of the relay lens system is assumed to be 1.0, and S3 designates the astigmatism coefficient of the whole relay lens system when the focal length thereof is assumed to be 1.0, respectively.

Abstract: In an eyepiece zoom lens having a lens configuration constituted by seven lenses in three groups, predetermined conditional expressions are satisfied so as to realize a zoom ratio of 3 while attaining a sufficient eye relief and ameliorating various kinds of aberration. The first lens group G.sub.1 is made stationary, whereas the second lens group G.sub.2 and the third lens group G.sub.3 are made as movable groups which, when changing the power, respectively move in directions opposite to each other on the optical axis while holding therebetween an object image which is formed between these two lens groups. Further, the eyepiece zoom lens is configured so as to satisfy the following conditional expressions:5<f.sub.1 /f.sub.m <7, 3.5<f.sub.2 /f.sub.m <4.5,-3.7<f.sub.3 /f.sub.m <-3, 0.1<S.sub.12 /f.sub.m <1.0, 6.0<S.sub.23 /f.sub.m <8.0,.nu..sub.1 <35, .nu..sub.2 <35, .nu..sub.

Abstract: An eyepiece comprises, in the following order from the image side, a first lens unit G1 including a negative lens with a concave surface facing the image, a second lens unit G2 including a cemented lens composed of a negative lens and a positive lens arranged in the mentioned order from the image side, a third lens unit G3 including a cemented lens composed of a positive lens and a negative lens, and a fourth lens unit G4 including a positive lens.

Abstract: An ocular lens includes, sequentially from an object side, a first lens unit G1 exhibiting a negative refracting power on the whole and a second lens unit G2 exhibiting a positive refracting power on the whole. An object-side focal surface of the second lens unit G2 is positioned between the first and second lens units G1, G2. At least one lens surface of the first lens unit G1 is formed in an aspherical shape.

Abstract: A wide field eyepiece with inside focus includes first and second lens groups G.sub.1 and G.sub.2. The first lens group G.sub.1 includes a negative cemented lens component and the second lens group G.sub.2 includes a positive lens component whose face of greater curvature is faced toward the eye point, a positive cemented lens component and a positive lens component whose face of greater curvature is faced toward the object. The first and second lens groups G.sub.1 and G.sub.2 are arranged in this order from the object side. The following formulae (1), (2) and (3) are satisfied,-4<f.sub.1 /f<-1.5 (1)1.3<f.sub.2 /f<2 (2)1<d.sub.12 /f<3.5 (3)wherein f represents the focal length of the overall lens system, f.sub.1 represents the focal length of the first lens group G.sub.1, f.sub.2 represents the focal length of the second lens group G.sub.2 and d.sub.12 represents the axial air separation between the first lens group G.sub.1 and the second lens group G.sub.2.

Abstract: A re-imaging objective optical system provides superior optical performance while having a short overall length and a relatively simple composition. The system has, in order from the object side of the optical system, a front lens group (G1) composed of a first lens group having a positive lens component (L1), a second lens group having a biconcave negative lens component (L2) and a third lens group having a positive lens component (L3); and a back lens group G2 composed of a cemented double lens element with components (L4 and L5) and a positive lens component (L6). The spatial or primary image I.sub.1 from the objective optical system is formed on the optical path between the first lens group and the second lens group.

Abstract: A stereomicroscope includes an objective lens for converting light from an object into parallel beams, an imaging lens for forming an image of the object, a prism for erecting the object image, and an eyepiece for observing the object image so that the object image is viewed stereoscopically through the eyepiece, in which the eyepiece is constructed from a single lens system equipped with a variable magnification optical system and an eye lens whose diameter is larger than a viewer's interpupil distance, and optical paths from the object image to the viewer's eyes traverse the positions outside the optical axis of the eyepiece. Thus, the stereomicroscope dispenses with the need for adjustment of the interpupil distance, causes the freedom of the eyepoint to be increased, and allows a viewer to observe the image from any direction whatsoever.

Abstract: An eyepiece lens system for endoscopes comprising a plurality of lens components and using at least one aspherical surface. This eyepiece lens system is composed of a small number of lens elements and has favorably corrected aberrations.

Abstract: A compact Galilean-type zoom finder suitable for compact cameras, and the like whose zoom ratio is about 2. The zoom finder is comprised of four units having negative, negative, positive and negative refractive powers in order from an object side and a movable fixed aperture framing window. The first and the fourth lens units are fixed and the second and the third lens units are moved to perform zooming. The moving framing window helps to delineate the field of view.

Abstract: An eyepiece lens system comprising, in the order from the side of incidence of rays, a first lens unit having positive or negative refractive power as a whole and a second lens unit having positive refractive power as a whole, said eyepiece lens system having little aberrations, image surface flatness excellent to the marginal portions of visual field, a high eye point and a wide visual field.

Abstract: An objective lens system comprising four pieces lens arranged from a light source side, in order, a cemented lens which has a convex first lens and negative second lens cemented with each other, a convex third lens and a positive meniscus forth lens where convex surface thereof is faced toward the light source side.

Abstract: An objective optical system for endoscopes comprising, in the order from the object side, a front negative lens unit, an aperture stop, a positive lens unit comprising at least one positive lens component, and an infrared cut filter arranged immediately before said aperture stop, said objective optical system being adapted so as to allow rays to be incident on said filter at heights lower than the outside circumference of said filter.

Abstract: A compact Galilean-type zoom finder suitable for compact cameras, and the like whose zoom ratio is about 2. The zoom finder is comprised of four units having negative, negative, positive and negative refractive powers in order from an object side. The first and the fourth lens units are fixed and the second and the third lens units are moved to perform zooming.

Abstract: An ocular system is disclosed which is composed of at least three lens elements for constituting, in order from the eye side, at least first and second lens units. At least one of the lens elements is made of resin. Two of the lens elements are substantially cemented together. In addition, an aspherical plastic lens is effectively used in the system.

Abstract: The present invention relates to an improved collimator assembly that includes two separate optical paths. Each optical path passes through a corrector lens arrangement substantially centered and aligned with one of two eyepiece lens assemblies. Each corrector lens arrangement is constructed so as to selectively refract light passing through it, in such a manner so as to counteract and reduce the axial chromatic aberrations that occur in the eyepiece lens assemblies.