Abstract: An optical imaging system includes a first lens, as second lens, a third lens, a fourth lens, and a fifth lens. The first lens includes a positive refractive power and a convex image-side surface. The second lens includes a positive refractive power, and the third lens includes a negative refractive power. The fourth lens includes a positive refractive power, and the fifth lens includes a positive refractive power. The first to fifth lenses are sequentially disposed from an object side toward an imaging plane.

Abstract: The objective lens unit includes, a front lens group having a negative refractive power, a diaphragm, and a rear lens group having a positive refractive power, in order from an object side. The front lens group includes a negative lens having a concave surface facing an image surface side, and a positive lens having a convex surface facing the object side, and the rear lens group includes a positive lens having a convex surface facing the image surface side and a cemented lens in which a positive lens and a negative lens are cemented. The endoscope objective lens unit satisfies ?1.6<fF/fR<?1.2 and ?1.3<f3/fF<?0.7. Note that fF and fR are focal lengths of the entire system of the front lens group and the rear lens group, and f3 is a focal length of a positive lens, in the rear lens group.

Abstract: An optical imaging system includes a first lens, as second lens, a third lens, a fourth lens, and a fifth lens. The first lens includes a positive refractive power and a convex image-side surface. The second lens includes a positive refractive power, and the third lens includes a negative refractive power. The fourth lens includes a positive refractive power, and the fifth lens includes a positive refractive power. The first to fifth lenses are sequentially disposed from an object side toward an imaging plane.

Abstract: An optical microscopy device for detecting cellular components of a sample, includes: a light source apparatus for emitting a light beam; a specimen carrier, which can be positioned in the beam path of the light beam, for receiving the sample; an objective lens which is provided downstream of the specimen carrier in the beam path of the light beam; and a camera chip which has pixels of a predefined pixel size, the camera chip being designed to detect the light beam after it passes through the objective lens and being designed to generate a camera image, a field number in the intermediate image downstream of the objective lens being greater than 25 millimeters.

Abstract: A fluidic light field camera is disclosed herein. The fluidic light field camera includes a fluidic objective lens; a fluid control system operatively coupled to the fluidic objective lens, the fluid control system to change the shape of the fluidic objective lens in accordance with the amount of fluid therein; a microlens array disposed behind the fluidic objective lens; a sensor array disposed behind the microlens array; and a data processing device operatively coupled to the fluid control system and the sensor array, the data processing device configured to vary the focal point of the fluidic light field camera by using the fluid control system to control the shape of the fluidic objective lens, thereby enabling all portions of an image being captured by the fluidic light field camera to be in focus during a single recording cycle of the fluidic light field camera.

Abstract: An optical imaging system includes a first lens including a positive refractive power, a concave object-side surface, and a convex image-side surface. The optical imaging system also includes a second lens including a positive refractive power, a convex object-side surface, and a concave image-side surface. The optical imaging system further includes a third lens, a fourth lens, and a fifth lens. The first to fifth lenses are sequentially disposed from an object side to an image side.

Abstract: An optical lens assembly includes a first lens of positive refractive power, a second lens of refractive power, at least one of the object surface and the image surface being aspherical, a fourth lens of refractive power, a fifth lens of a concave object surface near its optical-axis and both the object surface and the image surface being aspherical so that the Abbe number ?4 of the fourth lens, the Abbe number ?5 of the fifth lens, an air gap G12 between the first lens and the second lens, an air gap G23 between the second lens and the third lens, an air gap G45 between the fourth lens and the fifth lens, the second thickness T2 of the second lens, the third thickness T3 of the third lens, the fourth thickness T4 of the fourth lens, and the fifth thickness T5 of the fifth lens satisfy 18??4??5?50 and (G12+T2+G23+T3+T4+G45+T5)/G34?6.3.

Abstract: Apparatuses, devices and systems and methods for microscopy and optical data storage in transparent media, as well as for laser material processing of transparent or semi-transparent materials. Optics for diffraction limited focusing inside transparent or semi-transparent media comprising aplanatic focusing optical system and positive meniscus lens where reciprocal positions of the components and a transparent medium are optimized with criterion of minimized aberration providing diffraction limited internal focusing at a given depth inside the said transparent medium. For modern high resolution microscopy the optical components have achromatic and apochromatic optical designs. Immersion in space between the meniscus lens and the transparent material is used to increase the system numerical aperture.

Abstract: There is provided an endoscope objective optical system with a small size and a high image quality, and in which, an adequate space for disposing a visual-field direction converting element is secured. The endoscope objective optical system, comprising in order from an object side: a first group having a negative refractive power; an aperture stop; and a second group having a positive refractive power, wherein the first group includes in order from the object side, a first lens having a negative refractive power and a visual-field direction converting member, and the second group includes in order from the object side, a second lens having a biconvex shape and a cemented lens in which a third lens having a positive refractive power and a fourth lens having a negative refractive power are cemented in this order, and the endoscope objective optical system satisfies the following conditional expressions (1), (2), (3), and (4) 2.4?d1/f?4.6 ??(1) 1.85?f2/f?2.6 ??(2) ?50?r21/r22??0.4 ??(3) 2.01?f03/f?2.

Abstract: An imaging lens includes a first lens having negative refractive power; a second lens having positive refractive power; a third lens; and a fourth lens arranged in the order from an object side to an image plane side. The first lens has an image plane-side surface having a positive curvature radius. The first lens has a specific focal length to satisfy a specific conditional expression.

Abstract: The present invention relates to an anti-reflective coating composition providing improved scratch resistance, a method for manufacturing an anti-reflective film using the same, and an anti-reflective film manufactured thereby. According to the present invention, provided are a composition that is able to form a coating layer having improved surface scratch resistance, while forming one or more layers by a single coating process, and an anti-reflective film manufactured by using the same.

Abstract: An F-theta objective is provided that has five individual lenses with a first individual lens as biconcave lens with a focal length, a second individual lens as meniscus with a focal length, a third individual lens as meniscus with a focal length, a fourth individual lens as a biconvex lens with a focal length and a fifth individual lens as a plano-convex lens with a focal length and a total focal length f of the F-theta objective. A ratio between the focal lengths to the total focal length satisfies predetermined conditions.

Abstract: A stereoscopic imaging apparatus includes: an objective optical system having a function of imaging a subject as a real image or a virtual image; and plural imaging optical systems that image plural subject luminous fluxes output from different paths of the objective optical system again as parallax images using plural independent optical systems, wherein, in the case where a focal length value when the objective optical system images the subject as the real image is positive and the focal length value when the objective optical system images the subject as the virtual image is negative, a focal distance (f) of the objective optical system and a distance (L) from a rear principal point of the objective optical system to a front principal point of the imaging optical system is set to values that satisfy the following equation |f/(L?f)|?1.

Abstract: A projection optical system substantially consists of a first optical system composed of a plurality of lenses and a second optical system composed of one reflection mirror having a convex aspherical surface arranged in this order from the reduction side and is configured, when an air space between the first optical system and the second optical system is taken as T12 and a displacement in a direction of the optical axial from a position of maximum effective height on the magnification side lens surface of the lens disposed on the most magnification side in the first optical system to the vertex of the lens surface is taken as Zf, to satisfy a conditional expression (1): 0.1<Zf/T12<1.0, in which an image formed on a conjugate plane on the reduction side is magnified and projected onto a conjugate plane on the magnification side.

Abstract: A wide range zoom system, for microscopes. The zoom system includes five lens groups, of which, starting at the object side, the second and fourth lens group are displaceable in the axial direction relative to the first, third and fifth lens group. A stop of variable opening diameter that is stationary relative to the first, third and fifth lens group is provided between the second and fourth lens group, wherein the maximum opening diameter of said stop is in middle zoom magnifications. As magnification increases, the object-side aperture increases non-linearly in relation to the magnification, such that in regions of low magnifications the object-side aperture increases more sharply than in regions of higher magnifications.

Abstract: Provided is an endoscope objective optical system that is constituted of, in order from the object side, a positive first group, an aperture stop, and a positive second group, wherein the first group is constituted of a negative first lens whose surface on the object side is flat and a positive second lens; the second group is constituted of a combined lens formed of a positive third lens and a negative fourth lens; and Conditional Expressions (1) to (3) are satisfied. F31, F32, and f are the focal lengths of the third lens, the fourth lens, and the entire system, respectively; and R3 and R4 are the radii of curvature at the object-side surface and the image-side surface of the second lens, respectively. 1.2<f31/f<1.55 . . . (1), ?2.8<f32/f<?1.98 . . . (2), and 0.38<|R4+R3|/|R4?R3|<0.77 . . . (3).

Abstract: Described is a microscope objective (10, 100, 200) having an objective housing (12) which contains a lens system including a lens unit (60) capable of being moved along the optical axis (O) of the lens system to compensate for the thickness of the coverslip, and further having an adjusting device for adjusting the lens unit (60), said adjusting device including a drive unit (14, 102, 202) and a transmission (42, 44, 46, 48, 50, 52, 54, 56, 62) which is drivable by the drive unit (14, 102, 202) and coupled to the lens unit (60). According to the present invention, the drive unit (14, 102, 202) has a motor (34) and is mounted on the objective housing (12).

Abstract: A high-aperture immersion objective, in particular for confocal applications in fluorescence microscopy and for TIRF applications, having three subsystems of lenses and/or lens groups. The design of the subsystems has made it possible for a relatively large object field of 0.25 mm to be present in the case of a high-resolution numerical aperture of 1.49. Furthermore, improved transparency is possible up to a wavelength of 340 nm.

Abstract: A photographing optical lens assembly comprising, in order from an object side to an image side, a first lens element with positive refractive power, a second lens element with negative refractive power, a third lens element with refractive power, a fourth lens element with positive refractive power and a plastic fifth lens element is mentioned. The third lens element comprises a convex object-side surface and a concave image-side surface. The fourth lens element comprises a convex object-side surface and a convex image-side surface. The fifth lens element comprises a concave image-side surface. The surfaces of the third and fifth lens elements are aspheric. The fifth lens element comprises at least one inflection point. By adjusting the refractive power of the third lens element, and adjusting the total length of the photographing optical lens assembly, the total volume of the lens assembly is reduced, and the image quality is improved.

Abstract: A wide range zoom system, for microscopes. The zoom system includes five lens groups, of which, starting at the object side, the second and fourth lens group are displaceable in the axial direction relative to the first, third and fifth lens group. A stop of variable opening diameter that is stationary relative to the first, third and fifth lens group is provided between the second and fourth lens group, wherein the maximum opening diameter of said stop is in middle zoom magnifications. As magnification increases, the object-side aperture increases non-linearly in relation to the magnification, such that in regions of low magnifications the object-side aperture increases more sharply than in regions of higher magnifications.

Abstract: An immersion microscope objective formed of thirteen or fewer lens elements includes, in order from the object side, first and second lens groups of positive refractive power, a third lens group, a fourth lens group having negative refractive power with its image-side surface being concave, and a fifth lens group having positive refractive power with its object-side surface being concave. The first lens group includes, in order from the object side, a lens component that consists of a lens element of positive refractive power (when computed as being in air) and a meniscus lens element having its concave surface on the object side. Various conditions are satisfied to ensure that images of fluorescence, obtained when the immersion microscope objective is used in a laser scanning microscope that employs multiphoton excitation to observe a specimen, are bright and of high resolution. Various laser scanning microscopes are also disclosed.

Abstract: An endoscope objective lens unit includes a front lens group and a rear lens group with a diaphragm interposed therebetween. The front lens group includes a first lens and a second lens, and the rear lens group includes a third lens, a fourth lens and a fifth lens. The endoscope objective lens unit satisfies following expressions (1A) to (4): (1A) ?3 <SF ?1; (2) ?3 <Fr/Ff <?1.1; (3) ?1.6 <Ff/f <?0.6; and (4) Ff/f1 <1.6, where SF is a shape factor, Ff is a focal length of the front lens group, Fr is a focal length of the rear lens group, f is a focal length of the entire unit, and f1 is a focal length of the first lens.

Abstract: An objective lens includes, in order from an object side, a front group having negative refractive power, an aperture stop, and a rear group having positive refractive power, wherein the front group includes, in order from the object side, a first lens which is a negative meniscus lens with a convex surface turned to the object side and a second lens which is a negative lens with a concave surface turned to the object side; the rear group includes, in order from the object side, a positive third lens and a fourth lens made up of a positive lens and a negative lens cemented together, and the objective lens satisfies conditional expression (1) below: ?0.8<f—F/f—R<?0.3 ??(1), where f_F is a focal length of the front group, and f_R is a focal length of the rear group.

Abstract: An objective optical system includes, in sequence from the object side, a first group having positive refractive power and including a plano-convex lens with the convex surface facing the image side; a second group having positive refractive power and including a lens whose extreme-object-side lens surface is convex facing the object side; a third group having negative refractive power and including a lens whose extreme-image-side lens surface is concave facing the image side; a fourth group having positive refractive power and including a lens disposed on the extreme object side, whose image-side lens surface is convex facing the image side and a lens disposed on the extreme image side, whose object-side lens surface is convex facing the object side; and a fifth group having positive refractive power and including a combined lens by joining a convex lens and a concave lens, the joined surface having negative refractive power.

Abstract: A MEMS-based display device is described, wherein an array of interferometric modulators are configured to reflect light through a transparent substrate. The transparent substrate is sealed to a backplate and the backplate may contain electronic circuitry fabricated on the backplane. The electronic circuitry is placed in electrical communication with the array of interferometric modulators and is configured to control the state of the array of interferometric modulators.

Abstract: A microscope objective includes at least five lens components, which are divided into three groups that are, in order from an object side: a front group having a positive refracting power as a whole and having a meniscus lens component with an object-side surface thereof being concave toward the object side; a middle group having a positive refracting power as a whole and having a plurality of cemented lens components; and a rear group having a pair of concave air-contact surfaces arranged adjacent and opposite to one another, wherein the following conditions are satisfied: 3?D0/f?6 and 1?H2/H1?1.5, where D0 is an axial distance from an object surface to a rearmost surface of the microscope objective, f is a focal length of the microscope objective, H2 is a height of a marginal ray as emergent from the rearmost surface of the microscope objective, and H1 is a maximum height of the marginal ray as passing through the front group and the middle group.

Abstract: A MEMS-based display device is described, wherein an array of interferometric modulators are configured to reflect light through a transparent substrate. The transparent substrate is sealed to a backplate and the backplate may contain electronic circuitry fabricated on the backplane. The electronic circuitry is placed in electrical communication with the array of interferometric modulators and is configured to control the state of the array of interferometric modulators.

Abstract: An immersion microscope objective lens of the present invention has: in order from an object, a first lens group G1 having positive refractive power and having a cemented lens of a plano convex lens having a plane facing the object and a meniscus lens having a concave surface facing the object, and a single meniscus lens having a convex surface facing the object; a second lens group having positive refractive power and having a plurality of cemented lenses; and a third lens group having negative refractive power and having a cemented meniscus lens having a concave surface facing an image, and a cemented meniscus lens having a concave surface facing the object. And the following conditional expressions 0.12<d0/f<0.25, 0.04<?Ct(p)??Ct(n)<0.09 and ?0.03<?hg(p)??hg(n)<0.00 are satisfied.

Abstract: A wide field video endoscope objective and method of assembly the objective including four groups with five lenses, a mechanical housing containing the entire image forming elements, a aperture stop, a centering member and a retainer sleeve. The centering member is at first centered over the photo sensitive area of the chip and bonded to the surface of the cover glass. The retainer sleeve slides over said centering member and is glued to the centering member and the housing of the video chip. The objective housing with the optical elements is screwed on the centering member to adjust for focusing.

Abstract: An immersion microscope objective formed of thirteen or fewer lens elements includes, in order from the object side, first and second lens groups of positive refractive power, a third lens group, a fourth lens group having negative refractive power with its image-side surface being concave, and a fifth lens group having positive refractive power with its object-side surface being concave. The first lens group includes, in order from the object side, a lens component that consists of a lens element of positive refractive power (when computed as being in air) and a meniscus lens element having its concave surface on the object side. Various conditions are satisfied to ensure that images of fluorescence, obtained when the immersion microscope objective is used in a laser scanning microscope that employs multiphoton excitation to observe a specimen, are bright and of high resolution. Various laser scanning microscopes are also disclosed.

Abstract: An endoscope objective lens for collecting combined bright field (white light) and fluorescence images includes a negative lens group, a stop, and a positive lens group. The lens has a combination of large entrance pupil diameter (?0.4 mm) for efficiently collecting weak fluorescence light, large ratio between the entrance pupil diameter and the maximum outside diameter (Dentrance/Dmax larger than 0.2), large field of view (FFOV?120°) and favorably corrected spherical, lateral chromatic and Petzval field curvature for both visible and near infrared wavelengths.

Abstract: An immersion type microscope objective is configured by, in order from the object side to an image side, a positive lens group Ga including a cemented lens obtained by cementing a plano-convex lens whose plane surface faces the object side to a meniscus lens whose concave surface faces the object side, and a positive single lens, a positive lens group Gb including a cemented lens, a lens group Gc including at least one cemented lens, a lens group Gd having a meniscus lens having a strongly concave surface that faces the image side, and a lens group Ge having a negative lens having a strongly concave surface that faces the object side.

Abstract: An immersion type microscope objective is configured by, in order from the object side to an image side, a positive lens group Ga including a cemented lens obtained by cementing a plano-convex lens whose plane surface faces the object side to a meniscus lens whose concave surface faces the object side, and a positive single lens, a positive lens group Gb including a cemented lens, a lens group Gc including at least one cemented lens, a lens group Gd having a meniscus lens having a strongly concave surface that faces the image side, and a lens group Ge having a negative lens having a strongly concave surface that faces the object side.

Abstract: An immersion microscope objective formed of thirteen or fewer lens elements includes, in order from the object side, first and second lens groups of positive refractive power, a third lens group, a fourth lens group having negative refractive power with its image-side surface being concave, and a fifth lens group having positive refractive power with its object-side surface being concave. The first lens group includes, in order from the object side, a lens component that consists of a lens element of positive refractive power (when computed as being in air) and a meniscus lens element having its concave surface on the object side. Various conditions are satisfied to ensure that images of fluorescence, obtained when the immersion microscope objective is used in a laser scanning microscope that employs multiphoton excitation to observe a specimen, are bright and of high resolution. Various laser scanning microscopes are also disclosed.

Abstract: A microscope objective lens is disclosed that includes, in order from the object side, a first lens group having positive refractive power, a second lens group having positive refractive power that is movable along the optical axis, and a third lens group. The first lens group includes, in order from the object side, two meniscus lens components, each with its concave surface on the object side, and at least one positive lens component, and the third lens group has adjacent concave lens element surfaces that face each other and are in contact with air. Specified conditions may be satisfied, and one or more lens components in the first lens group and the second lens group may be movable.

Abstract: An immersion type microscope objective is configured by, in order from the object side to an image side, a positive lens group Ga including a cemented lens obtained by cementing a plano-convex lens whose plane surface faces the object side to a meniscus lens whose concave surface faces the object side, and a positive single lens, a positive lens group Gb including a cemented lens, a lens group Gc including at least one cemented lens, a lens group Gd having a meniscus lens having a strongly concave surface that faces the image side, and a lens group Ge having a negative lens having a strongly concave surface that faces the object side.

Abstract: By reducing the outer diameter, increasing the overall length, and correcting chromatic aberration well, the invention realizes an objective optical system and examination apparatus that are suitable for in-vivo examination with a sufficiently increased length and widened observation range. The invention provides a compact objective optical system and an examination apparatus comprising, in order from an object side: a first lens group having positive power; a second lens group including a compound lens; a third lens group formed of a biconvex lens; a fourth lens group having positive power and including a compound lens; and a fifth lens group having positive power. Joining surfaces of the compound lens included in the second lens group and the compound lens included in the fourth lens group have negative power.

Abstract: The invention is directed to a stereoscopic microscope objective. A microscope objective of this kind contains five lenses. The first lens, considered from the object side, has a focal length between ?2.11f and ?1.20f; f is the total focal length of the microscope objective. This is followed by a second lens with a focal length between 1.30f and 1.45f, a third lens with a focal length between 1.15f and 1.37f, a fourth lens with a focal length between 0.65f and 1.7f, and a fifth lens with a focal length between ?0.96f and 0.48f. Combined, the amount of the refractive power of the last two lenses is less than 0.31f. In the first lens and fifth lens, at least 80% of the refractive power is concentrated on the image-side surfaces. In the second lens, at least 60% of the refractive power is concentrated on the image-side surface. In the third lens, at least 60% of the refractive power is concentrated on the object-side surface.

Abstract: An afocal zoom lens for microscopes includes five lens units having, in order from the object side, positive, negative, negative, positive, and negative refracting powers. When the magnification of the afocal zoom lens is changed in the range from a low-magnification position to a high-magnification position, a first lens unit and a fifth lens unit are fixed, a second lens unit is moved toward the image side, and a fourth lens unit is moved toward the object side. The afocal zoom lens satisfies the following condition: 0?F2/F3?2.5 where the focal length of the second lens unit is represented by F2 and the focal length of a third lens unit is represented by F3. The third lens unit is constructed with at least one negative lens with a concave surface facing the object side.

Abstract: A spherical aberration corrector used in an electron microscope. The corrector has a spherical aberration correction optical system that permits the magnification to be varied. Rotational relation between two multipole elements within a plane perpendicular to the optical axis can be corrected without varying the phase angles of the multipole elements. A rotation-correcting lens is positioned within the focal plane of an electron trajectory formed between two axially symmetric lenses in the corrector to rotate electrons within a plane perpendicular to the optical axis.

Abstract: This invention relates to a microscope having an infinity-corrected objective and providing a flat field of view.

Abstract: The invention relates to an objective (2) for stereomicroscopes of the telescope type which comprises three optical assemblies (G1, G2, G3), the first assembly (G1) being arranged towards the object side and the third assembly (G3) being arranged towards a magnification changer (3L, 3R). The proposed objective (2) meets the conditions 0.44≦ENP/F≦0.6, where ENP denotes the diameter of the entry pupil of the magnification changer (3L, 3R) at the maximum magnification and F denotes the focal length of the objective (2), and tan(w1)≧0.16, where w1 denotes the maximum field angle of the objective (2) at the lowest magnification of the magnification changer (3L, 3R). The proposed objective (2) makes it possible to use a stereomicroscope with maximum resolution and a field of vision which is adapted to the full range of magnifications of the microscope.

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: A low magnification liquid immersion objective lens system uses an immersion liquid having a refractive index for the d-line within a range defined by a condition (1) shown below, and has a magnification &bgr; and a working distance WDL which satisfy the following conditions (2) and (3): 1.34≦ND≦1.80  (1) &bgr;≦15  (2) WDL≦0.35 mm.

Abstract: An objective lens for a microscope of the invention comprises, in order from an object side: a first lens group comprising a meniscus positive lens with a concave surface facing the object; a second lens group including a cemented lens and having a positive refractive power; a third lens group including a cemented lens and having a positive refractive power; a fourth lens group comprising a cemented lens; and a fifth lens group comprising a cemented lens.

Abstract: A liquid immersion type microscope objective lens comprises a first lens group G1 having a positive refracting power, a second lens group G2 having a positive refracting power, a third lens group G3 having a negative refracting power, a fourth lens group G4, and a fifth lens group G5, in order from an object side. The first lens group G1 has a cemented lens which comprises a plano-convex lens with the plane surface facing the object side and a meniscus lens with the concave surface facing the object side cemented together, and a positive meniscus lens with the concave surface facing the object side. The second lens group G2 has a plurality of cemented surfaces having a negative refracting power. The third lens group G3 has a cemented lens which comprises a negative lens, a positive lens, and a negative lens cemented together.

Abstract: A flow cytometry lens system features a low (<1.55) refractive index, near hemispheric plano-convex lens nearest a cytometry flow cell with the planar surface on the object side of the system and a convex surface with a radius of curvature in a range from 3.5 to 5.5 mm, followed by a pair of positive meniscus lenses having the concave sides facing the object side, with the surfaces of the second meniscus lens less sharply curved than the corresponding surfaces of the first meniscus lens, which in turn is followed by a positive doublet lens. The lens elements are optimized for providing a working distance of at least 1.75 mm, a field of view of at least 400 &mgr;m, a numerical aperture of at least 1.19 and a lens magnification in excess of 10.

Abstract: A microscope objective lens having a large aperture and yielding satisfactorily corrected, flat images. The microscope objective lens includes, in order from the object side, a first lens group G1 having an overall positive refractive power and a second lens group G2. The second lens group G2 includes plural Gauss lens sets G2A, G2C. Each Gauss lens set is formed of, in order from the object side, a meniscus-shaped optical element with its concave surface on the image side, and a meniscus-shaped optical element with its concave surface on the object side. Preferably, each of these meniscus-shaped optical elements is formed of two lens elements that are cemented together. Prescribed conditions are set forth to favorably correct various aberrations.

Abstract: An objective lens for a microscope of the invention comprises, in order from an object side: a first lens group comprising a meniscus positive lens with a concave surface facing the object; a second lens group including a cemented lens and having a positive refractive power; a third lens group including a cemented lens and having a positive refractive power; a fourth lens group comprising a cemented lens; and a fifth lens group comprising a cemented lens.

Abstract: A Galileo type stereomicroscope permits an observer to change its eye-level by varying a space between an objective lens and a pair of a focal variable magnification lenses. The Galileo type stereomicroscope satisfies following condition: Z>f0/3, where Z denotes a variable range of the eye-level and f0 denotes a focal length of an objective lens to be used. The objective lens for the Galileo type stereomicroscope keeps imaging quality up to a periphery of an image field while the eye-level is changed.