Abstract: The invention relates to a fast macro lens that is well corrected for aberrations even at close range, and a camera comprising the macro lens. The macro lens comprises, in order from its object side, a first lens group G1 having positive power and a second lens group G2 having positive power. In the first lens group G1 a negative meniscus lens component concave on its object side is located nearest to the object side of the macro lens. Upon focusing from an object point at infinity to the closest object point, the first G1 and the second lens group G2 move independently toward the object side of the macro lens while the spacing between them varies.

Abstract: An optical system capable of reducing trouble in assembly and skew adjustment, comprising first and second optical lenses arranged so that their optical axes coincide or substantially coincide, wherein the first optical lens has a substrate comprised of an optical material, the substrate has a convex portion serving as a convex lens, a flat portion positioned around the convex portion, and an outer circumference portion positioned around the flat portion, a thickness of the substrate at the outer circumference portion is greater than a thickness of the substrate at the convex portion, and the outer circumference portion of the first optical lens and that of the second optical lens are fixed in place by an adhesive so that the convex portion of the first optical lens faces the convex portion of the second optical lens.

Abstract: The present invention discloses a dual-lens hybrid diffractive/refractive imaging system comprising: a first lens including a concave surface and a convex surface; and the second lens including a convex surface and a concave surface. The concave surface of the first lens is an objective surface facing the object. The convex surface faces the convex surface of the second lens, while the concave surface of the second lens faces the charge-coupled device (CCD) through a filter. Any surface of the first lens and the second lens is spheric or aspheric. Moreover, the imaging system comprises at least one diffractive surface, referred to as a hybrid diffractive/refractive surface, formed on any surface of the two lenses. Therefore, aberration is eliminated and image quality is improved without increasing the number of lenses.

Abstract: An optical beam transformation system includes a first and a second optical element, each of which has a non-reentrant surface. The system transforms a substantially non-uniform optical input beam (such as a Gaussian) to a substantially uniform output beam. The first and second optical elements are arranged in either a Keplerian or Galilean configuration. The aspheric surface of the second optical element is related to the aspheric surface of the first optical element by a ray-tracing function that maps substantially all of an input light beam that is incident on the first optical element to a collimated output light beam that is output from the second optical element. Preferably, the output light beam has a Fermi-Dirac intensity distribution, and the ray-tracing function maps the input light beam to the output beam out to the (1/e)6 intensity radius of the input light beam.

Abstract: A compact photographic lens for a digital camera is disclosed. The photographic lens has only two lens elements, yet provides excellent imaging even at the periphery of the image field. The photographic lens of the invention and an image sensor, together, fit within a volume of about 10 cm3 The lens is formed of, in order from the object side, a biconvex lens element having two aspherical surfaces, and a positive meniscus lens element having two aspherical surfaces. The convex surface of the meniscus lens element is positioned on the image side, and various conditions are satisfied in order to provide the photographic lens with a short overall length while favorably correcting various aberrations.

Abstract: A single focus lens formed of only two lens groups, both of positive refractive power, with each lens group being formed of only a single lens. The lens of the first lens group has at least one of its surfaces aspherical, and the lens element of the second lens group has at least one of its surfaces aspherical and is convex on the object side. In addition, the following conditions are satisfied in order to provide a single focus lens suitable for use in a highly portable, compact camera, such as a digital camera: &ugr;d2>50 |f/f1|<0.75 where &ugr;d2 is the Abbe number, at the d line, of the lens element that forms the second lens group, f is the focal length of the single focus lens, and f1 is the focal length of the lens that forms the first lens group.

Abstract: A single focus lens formed of only two lens groups, both of positive refractive power, with each lens group being formed of only a single lens. The lens of the first lens group has at least one of its surfaces aspherical, and the lens element of the second lens group has at least one of its surfaces aspherical and is convex on the object side.

Abstract: A projection lens including a first lens group, a diaphragm, and a second lens group, which are disposed in that order from a screen to an image source. The first lens group includes an aspherical lens and at least one positive lens, and has a positive refractive power. The second lens group includes at least one set of combined lenses and an aspherical lens, and has a positive refractive power. A lens gap in the first lens group is moved to perform a focusing operation. It is possible to provide a wide-angle projection lens which uses few lenses and has a long back focus and focal length when BF/F is greater than 1.87, and HF2/F2 is greater than 0.22 but less than 0.57, where F denotes the focal length of the projection lens, BF denotes the distance in air from a last lens surface of the second lens group to the image source, F2 denotes the focal length of the second lens group, and HF2 denotes the location of a front principal point of the second lens group.

Abstract: A taking lens comprises a first meniscus lens opposing its convex surface to an object side and a second lens having a positive power. An image side surface of the first lens and an object side surface of the second lens are aspherical.

Abstract: A taking lens comprises, in order from the object side, a first lens group which consists of a positive power first meniscus lens element convex to the object side and a second lens group which consists of a positive power second meniscus lens element concave to the object side. The first lens element at an image side surface and the second lens element at either one of image and object side surfaces are configured aspheric and the taking lens satisfies the following conditions: |f1|>f2 R1>R2 where f1 is the focal length of the first lens element, f2 is the focal length of the second lens element, and R1 and R2 are the radii of curvature of the object side and image side surfaces of the first lens element.

Abstract: A rear-focusing telephoto lens system includes a positive front lens group, and a positive rear lens group, in this order from the object The front lens group includes at least two positive lens elements, each of which has a large-curvature convex surface facing toward the object, and a negative lens element having a large-curvature concave surface facing toward the image. The rear lens group includes at least one lens element which has a convex surface facing toward the object, and is positioned at the most object-side in the rear lens group. Upon focusing, only the rear lens group moves along the optical axis, and the lens system satisfies the following condition: 0.5<f/fF<0.8  (1) wherein f designates the focal length of the entire lens system; and fF designates the focal length of the front lens group.

Abstract: An objective lens includes a first lens unit constructed with a plurality of single lenses, having a negative power as a whole, and a second lens unit constructed with a plurality of single lenses, arranged on the object side of the first lens unit.

Abstract: A lens assembly particularly suited to use with high resolution digital cameras and other portable electronic devices. The lens includes a positive powered front group having one or two elements and a second, aberration correcting, rear group having in order from the front a bi-concave element, a meniscus element and a bi-concave element. The aperture stop plane is just in front of the front group. A combined operator and shutter device is positioned at the aperture stop plane. All of the lens elements are made of glass and have spherical surfaces.

Abstract: A fast responding optical modulating device for a high-density recording using in an optical pickup includes a light source, an optical modulator and a pair of lenses. The pair of lenses are so arranged that the distance between the lenses is shorter than the sum of each focal length of the lenses. The device can adjust an optical spot size at the center of the optical modulator by changing the position of the lenses without altering the whole length between the light source and optical modulator. Therefore, the device can increase the rise time as desired and the optical efficiency in optical modulation for high-density recording which uses a short wavelength light source, and moreover, has an effect of simplifying the high-density recording.

Abstract: A taking lens system has, from the object side, a front lens unit, an aperture stop, and a rear lens unit. The front lens unit is composed of two lens elements that are, from the object side, a positive glass element and a negative plastic lens element. The rear lens unit has a positive plastic lens element disposed at the image-side end thereof. On the object side of this positive plastic lens element is disposed solely a lens element made of glass.

Abstract: A telescopic objective lens system comprises a positive first lens group and a second lens group, in this order from the object. The second lens group comprises a first sub-lens group and a second sub-lens group, wherein the first sub-lens group is combined with the first lens group to be used for correcting axial chromatic aberration, the second sub-lens group is combined with the first lens group to be used for correcting field curvature; and wherein the combination of the first lens group and the first sub-lens group, and the combination of the first lens group and the second sub-lens group can be alternatively selected.

Abstract: An image-reading lens is formed of a two lens elements of meniscus shape, one with its convex surface on the most object-side of the image-reading lens and one with its convex surface on the most image-side of the image-reading lens. An intermediate lens element of negative refractive power may be optionally provided. A zone plate diffractive optical surface having different depth zones surrounding a vertex is formed on at least one aspherical surface of the two lens elements of meniscus shape so as to correct simltaneously for both lateral color and curvature of field. Another surface, preferably of the same lens element having the zone plate diffractive/aspherical surface, is made aspherical. Of the two lens elements of meniscus shape, one is made of plastic material and the other is made of non-plastic material. The image reading lens provides a high image quality having a small temperature dependence, despite one lens element thereof being made of plastic material.

Abstract: A projection lens for use with a pixelized panel (LCD) is provided. The lens has two positive lens units with an aperture stop between them. The optical powers of each of the units are such that f1 is substantially shorter than f2, where f1 and f2 are the focal lengths of the first lens unit and the second lens unit, respectively, the first lens unit being on the system's long conjugate side and the second lens unit being on the short conjugate side. The ratio of f1 to f2 is preferably less than about 0.75.

Abstract: A high numerical aperture objective lens for focusing a laser beam consists of a first lens element of positive optical power intercepting the laser beam and a second lens element of positive optical power located adjacent to the first lens element. The first lens element and the second lens element have identical surface profiles.

Abstract: A reimager comprises precisely two positive lenses wherein the chromatic longitudinal aberration lies within the depth of focus and the thermal image position variation likewise lies within the depth of focus over a temperature range of more than .+-.30.degree. (in the embodiment from -40.degree. C. to +70.degree. C.). Aspheric and diffractive surfaces are utilized and, if required, are joined on respective lens surfaces (31, 51, 53, 71, 73).

Abstract: An apochromatic lens system which includes, in this order from the object, a positive first lens group and a positive second lens group; wherein the following conditions are satisfied:.nu..sub.I+ <80 (1).nu..sub.II+ >70 (2)1.1<f.sub.I /f<2.0 (3)wherein.nu..sub.I+ designates the largest Abbe number of a positive lens element in the first lens group;.nu..sub.II+ designates the largest Abbe number of a positive lens element in the second lens group;f.sub.I designates the focal length of the first lens group; andf designates the focal length of the entire lens system.

Abstract: A reading lens system composed, in order from the object side, of a first positive biconvex lens component, a second positive meniscus lens component convex toward the image side and an aperture stop disposed on the image side of the second lens component. By setting a distance as measured from a first surface to an aperture stop of the reading lens system adequately, it is configured so as to have a short total length and allow little variation of a size of an image even when the image is defocused due to a variation of an object location.

Abstract: A method for designing an objective lens apparatus formed by at least two lenses, a first lens and a second lens, which includes the steps of: measuring aberration which occurs when a light beam is converged by the first lens; setting the first lens is set such that the aberration occurring in the first lens satisfies Marechal's criterion, in accordance with the measurement results; measuring aberration which occurs when a light beam is converged by the first lens and the second lens; and setting the second lens such that the aberrations occurring in the first lens and the second lens satisfy Marechal's criterion, in accordance with the measurement results. Accordingly, an objective lens apparatus with a small aberration and a large numerical aperture NA can be designed by this method.

Abstract: An image pickup lens system consists of first and second lens elements arranged in this order from the object side. The first lens element is a meniscus lens having a weak refractive power and concave toward the object side, and the second lens element has a positive refractive power. The following formula is satisfied.0.19.ltoreq.d.sub.1 /f.ltoreq.1.7wherein d.sub.1 represents the central thickness of the first lens element and f represents the focal length of the overall lens system.

Abstract: A wide angle lens comprises in order from the object end an aperture stop, a first meniscus lens .sub.L1 having a convex object end surface and a second positive power lens element L.sub.2, the lens satisfying the following conditions:-0.10<f.sub.2 /f.sub.1 <0.74.0<f/R.sub.1 <7.50<f/R.sub.3 <1.60.01<D/f<0.22where f.sub.1, f.sub.2 and f are the focal length of the first lens L.sub.1, the second lens L.sub.2 and the overall lens system, respectively, R.sub.1 and R.sub.3 are the radii of the object end surfaces of the first and second lenses L.sub.1 and L.sub.2, respectively, and D is the axial distance between the object end surface of the first lens L.sub.1 and the image plane.

Abstract: An eyepiece lens system comprising a first positive lens component and a second positive lens component: the first lens component being composed of a single positive lens element, and the second lens component being composed of a single cemented doublet consisting of a positive lens element and a negative lens element. This eyepiece lens system has distortion which is corrected favorably by selecting an adequate refractive power for a cemented surface of the cemented doublet and is configured so as to have a sufficiently long eyepoint distance.

Abstract: An objective lens system includes a positive first lens group having a positive lens element and a negative lens element, and a positive second lens group, in this order from the object side. The objective lens system satisfies the following relationships:1.10<f.sub.1 /f<2.00,.vertline..theta.p-.theta.n.vertline.<0.02, and0.3<L/f<0.6wherein f represents the focal length of the whole lens system, f.sub.1 represents the focal length of the first lens group, .theta.p, .theta.n represent the mean values of partial dispersion ratios of the positive and negative lens elements, represented by (n.sub.g n.sub.F)/(n.sub.F -n.sub.C), respectively, and L represents the distance between the first and second lens groups.

Abstract: A photographing lens includes a first lens group, a diaphragm, and a positive second lens group, in this order from the object side. The photographing lens satisfies the following relationships: .vertline.f/f.sub.1 .vertline.<0.2, and 0.7<h.sub.I-1 /h.sub.I-L <1.0. In the above relationships, "f" designates the focal length of the entire photographing lens, "f.sub.1 " the focal length of the first lens group, "h.sub.I-1 " the height of the incident point of paraxial rays on axis on the first surface of the first lens group, and "h.sub.I-L " the height of the incident point of paraxial on-axis rays on the last surface of the first lens group, respectively.

Abstract: An image forming lens system including a positive front lens group, a diaphragm, and a rear lens group, in this order from an object to be imaged. The front lens group is made of optical glass. The rear lens group is made of a single meniscus plastic lens having opposed aspherical lens surfaces with a concave surface adjacent to the diaphragm. The lens system satisfies the following relationships:f.sub.0 .multidot..vertline.1/f.sub.R-1 +1/f.sub.R-2 .vertline.<0.3-4<f.sub.0 /r.sub.R-1 <-0.7.DELTA.X.sub.R-1 /f.sub.0 <0.DELTA.X.sub.R-2 /f.sub.0 <00.1<d.sub.R /f.sub.0.In the above, f.sub.R-1 (=r.sub.R-1 /n-1) represents the focal length of the first surface of the plastic lens, f.sub.R-2 (=r.sub.R-2 /1-n) represents the focal length of the second surface of the plastic lens, f.sub.0 represents the focal length of the whole lens system, n represents the refractive index of the plastic lens at a reference wavelength, r.sub.

Abstract: An optical system composed of two lens elements and a postpositional aperture stop, which are arranged in such a manner as to facilitate mounting on a casing of a camera or lens-equipped photographic film package and to suppress spherical aberration to ensure high quality performance from center to peripheral regions despite asymmetric lens disposition. The optical system includes, from the object side, a first lens element L.sub.1, a second lens element L.sub.2, and a postpositional aperture stop D located behind the second lens element on the side of the image field. The first lens element is a positive meniscus having a convex surface disposed on the object side, and the second lens element is a biconvex lens. Alternatively, the first lens element is a biconvex lens, and the second lens element is a positive meniscus having a convex surface disposed on the side of the image field. The image surface of the optical system is curved in a convace shape on the object side.

Abstract: A condenser lens system to collect light from a light source to illuminate a sample, which comprises in a named order from the light source side, a front group of positive refracting power having at least one lens and a rear group of positive refracting power having at least a positive lens for liquid immersion located closest to the sample, the positive lens for liquid immersion having a flat surface on the sample side.

Abstract: An illumination optical system for microscopes is constructed so that in a transmissive Kohler illumination optical system having a light source, a condenser lens system, and an aperture stop, the condenser lens system includes, in order from the side of incidence of light, a first lens unit having a positive lens and a negative lens, with a positive power as a whole, and a second lens unit having a negative lens and a positive lens, with a positive power as a whole. The aperture stop is placed between the first and second lens units, and the illumination optical system satisfies the condition:R.sub.1 /R.sub.2 >0where R.sub.1 is the radius of curvature of the foremost surface of the second lens unit and R.sub.2 is the radius of curvature of the rearmost surface of the second lens unit.

Abstract: An optical system includes a first lens group having a positive refractive power, a second lens group having a negative refractive power, and a third lens group having a positive refractive power. The third lens group comprises at least one positive lens and at least one negative lens. The second lens group is movable along a direction of an optical axis, and the third lens group is movable in a direction substantially perpendicular to the optical axis. The optical system satisfies:0.25<F1/FT<0.46where FT is the focal length of the optical system, and F1 is the focal length of the first lens group.

Abstract: An objective optical system of an optical information recording/reproducing apparatus includes a light source for emitting a generally parallel luminous flux, an objective optical system for converging the luminous flux emitted from the light source portion onto a medium and a chromatic aberration correcting element for correcting a chromatic aberration of the objective lens. The chromatic aberration correcting element is formed of three lens cemented together. A first lens and a third lens of the chromatic aberration correcting element have a same polarity power while a second lens has a different power from that of the first and third lenses. Incident and outgoing end faces of the chromatic aberration correcting element are formed as generally plane surfaces. A mechanism for independently actuating the objective lens at least in an optical axis direction is provided.

Abstract: A photographic lens includes a first meniscus lens having a positive refracting power, a convex face of which is directed to a photographic object side, and includes a second meniscus lens having a positive refracting power, a concave face of which is directed to the photographic object side. The first and second lenses are arranged in this order from the photographic object side. The photographic lens is composed in such a manner that the following conditional expressions are satisfied:0.60<f/f.sub.1 <0.75-3.2<(r.sub.4 +r.sub.3)/(r.sub.4 -r.sub.3)<-2.5where f represents a focal length of the photographic lens, f.sub.1 represents a focal length of the first meniscus lens, r.sub.3 represents a radius of curvature of the concave surface facing the object side of the second meniscus lens and r.sub.4 represents a radius of curvature of a surface facing an image plane side of the second meniscus lens.

Abstract: An optical system comprising two lens elements suitable for use in photographic devices such as single-use cameras having cylindrical image planes. This optical system can operate at F-numbers lower than F/11 while maintaining an excellent performance.

Abstract: A lighting apparatus has a lighting filament (3), a first lens (1) disposed at a fixed distance from the filament (3), divergent light from the filament falling directly on the first lens (1) which reduces but does not eliminate the divergence of the light in all directions about the optical axis upon passage of light through the first lens, and a sleeve (12) carrying a second lens (2) mounted for sliding movement relative to the box. The second lens (2) receives divergent light directly from the first lens (1) and reduces the divergence of the light upon passage of the light through the second lens, the focal length of the second lens being greater than 1 1/2 times the focal length of the first lens and the distance between the lenses being less than 1 1/2 times the focal length of the first lens. The illumination pattern is high-intensity but does not have a sharp contour so that it may be used in a surgical operating room.

Abstract: An objective lens system is provided and includes a spherical sapphire lens element, an aspheric first polymeric material lens element, and an aspheric second polymeric material lens element, all of which are axially aligned. The sapphire lens element is coupled to the first polymeric material lens element to form a meniscus shaped air lens element. When inserted as a component of an endoscope, the planar surface of the sapphire lens forms a robust outer distal window at the distal end of the endoscope and the flat surface of the second polymeric material lens element is attached to the relay lens system of the endoscope. The initial image of the observed area formed at the proximal end of the objective lens system is "buried" in a higher index medium than air thus allowing for easier coupling to a relay lens system leading to lower overall f/numbers.

Abstract: Disclosed is a projection optical system for projecting an original image onto a screen, including a projection lens comprising, in succession from the screen side, a first lens unit having positive refractive power, and a second lens unit having positive refractive power, and a reflecting member disposed between the first lens unit and the second lens unit of the projection lens for directing light from an illuminating light source to the original image through the second lens unit, one of a plurality of sub-lens units constituting the first lens unit being moved to thereby effect focusing.

Abstract: A wide-angle photographic lens system comprising a front lens unit having a positive refractive power, an aperture stop and a rear lens unit having a positive refractive power or a negative refractive power; the front lens unit comprising at least one positive lens component and at least one negative lens component, whereas said rear lens unit consisting of a positive lens component having a convex surface on the image side. This photographic lens system has a short total length (a length as measured from a first surface to an image side surface of the lens system and a small value of .SIGMA.d (a distance as measured from the first surface to a final surface thereof), and is suited for use with collapsible mount type cameras.

Abstract: An eyepiece which has a simple lens group construction of a relatively small number of lenses and which is reduced in aberration and increased in field angle. The eyepiece includes, as arranged in the order from an eyepoint side, a first lens group of a positive refractive power composed of a cemented lens of a negative lens and a positive lens, and a second lens group of a positive refractive power composed of a single positive lens. With the positive lens of the second lens group, at least one of the lens surfaces is an aspherical surface. With f representing the focal length of the eyepiece, f.sub.1 the focal length of the first lens group, and D the spacing between the first and second lens groups, the eyepiece satisfies the following conditions.1.05 f.sub.1 /f<2.5D/f<0.

Abstract: A lens system 10 suitable for use in imaging on film F in panoramic cameras 100. The lens system 10 comprising an aperture stop ST, a front lens unit 20 located behind the aperture stop ST, the front lens unit 20 including a triplet; and a rear lens unit 30, preferably a meniscus lens element 32, located behind the front lens unit 20. The triplet consists of two negative power lens elements 22, 26 and a positive power lens element 24 located between the negative power lens elements 22, 26.

Abstract: The invention is directed to a color corrected ocular having a very simple configuration and excellent correction characteristics. The ocular includes a single lens at the eye end with the single lens having an aspherical surface r.sub.2 and a two-element composite lens (2, 3). The surface r.sub.3 of the composite lens adjacent to the aspherical surface r.sub.2 is a planar surface. In another embodiment, the composite lens includes a planar-convex lens 2 and a planar-concave lens 3 which are cemented to each other at respective convex and concave surfaces. The spacing d.sub.1 between the single lens 1 and the exit pupil 4 is sufficiently large so that the ocular is also suitable for a wearer of spectacles.

Abstract: A lens system used for reading an image, the system being constructed of two lenses and presents sufficient performance for reading an image in an image scanner, a facsimile, etc. The system is constructed of a positive meniscus image-forming lens and a positive meniscus auxiliary lens. The convexes of both lenses face an object. The image-forming lens has at least one aspherical surface or it has an aspherical surface formed by joining an aspherical surface layer formed of a transparent material to the surface of a spherical glass lens. Both surfaces of the auxiliary lens are aspherical.

Abstract: An optical system for recording and reading information on an optical information medium such as a video disk, a mini disk, a magneto-optical disk, and a phase change disk. The optical system includes: a light source for irradiating the optical information medium with a light beam through a coupling lens and a objective lens; the coupling lens which is a spherical single lens; and the objective lens which is a double-sided aspherical lens and provided movable along an optical axis of the light source; in which the light source is located between the coupling lens and a focal point, at a side of the light source, of the coupling lens. The optical system defines the number of a numerical aperture on the side of the optical information medium, and a lateral magnification ratio of the optical system.

Abstract: An optical system for microscopes includes an objective lens for collimating beams of light emanating from an object and an imaging lens for forming parallel beams emerging from the objective lens into an image of the object at a predetermined position, and satisfies the equation:0.5 f<W<1.1 fwhere W is the variable amount of spacing from the contact surface of the objective lens to the surface of incidence of the imaging lens and f is the focal length of the imaging lens. Thus, the optical system for microscopes allows a large variable amount to be secured while holding a good imaging condition and is unsurpassed in extensity of the system to be able to accommodate various modes of observation.

Abstract: A lens system for a folding reflex camera is provided. The system includes: (a) a first group on the object side of the system's stop which (i) has a positive dioptric power, (ii) includes an aspheric surface, and (iii) has a concave surface adjacent to the stop; and (b) a second group on the image side of the stop consisting of either a single positive component or the combination of a single positive component and one or more focusing elements. The system includes at least two elements made of materials differing in dispersive powers where at least one of the elements is of plastic. The system can comprise just two plastic elements and even with such a simple configuration achieves excellent optical performance including a relatively flat field, relatively low distortion, and at least partial correction for lateral chromatic aberration.

Abstract: A collimator lens for an erasable and re-recordable magneto-optical disk system comprising a first positive lens, a second positive lens and a third negative lens arranged from a light outgoing side in order. The second and third lenses are cemented together and the cemented lens has a positive power. A refractive index of the first lens n1 is lower than 1.686.

Abstract: Described herein is a photographic wide angle lens which is composed of, from the object side thereof, a first lens of positive meniscus having a convex surface on the object side, and a second lens of positive meniscus having a concave surface on the object side, the wide angle lens having an aspheric surface at least on one of the four lens surfaces provided by the first and second lenses to improve astigmatism, spherical aberration and coma. The lens is also arranged to satisfy the condition of 0.85<fF/fR<1.15 (where fF and fR are focal lengths of the first and second lenses, respectively), thereby imparting symmetrical factors to maintain characteristics of the hypergon.

Abstract: An optical system for microscopes includes an objective lens for collimating beams of light emanating from an object and an imaging lens for forming parallel beams emerging from the objective lens into an image of the object at a predetermined position, and satisfies the equation:0.5 f<W<1.1 fwhere W is the variable amount of spacing from the contact surface of the objective lens to the surface of incidence of the imaging lens and f is the focal length of the imaging lens. Thus, the optical system for microscopes allows a large variable amount to be secured while holding a good imaging condition and is unsurpassed in extensity of the system to be able to accommodate various modes of observation.