Abstract: An objective optical system consists of in order from an object side to an image side, a first group having a positive refractive power, an aperture stop, a second group having negative refractive power, and a third group having a positive refractive power. Focusing is carried out by moving the second group. The objective optical system satisfies the following conditional expression (1?). ?16.6<G2f/FL<?11??(1?) where, G2f denotes a focal length of the second group, and FL denotes a focal length of the overall objective optical system in a normal observation state.

Abstract: An optical system includes, in order from an object side, a first lens group having positive refractive power, a second lens group having negative refractive power, and a third lens group having positive refractive power. The second lens group is moved upon carrying out focusing from an infinitely distant object to a close object, at least a portion of the third lens group is moved in a direction including a component perpendicular to an optical axis, and given conditional expressions is satisfied. Accordingly, an optical system excellently suppressing variations in aberrations generated upon vibration reduction, an optical apparatus equipped therewith, and a method for manufacturing the optical system are provided.

Abstract: A retrofocus-type wide angle lens includes a first lens group having negative refractive power as a whole, a second lens group having positive refractive power as a whole, a stop, and a third lens group having positive refractive power as a whole, which are arranged in this order from the object side of the retrofocus-type wide angle lens. Further, the first lens group includes two negative meniscus lenses, each having a convex surface facing the object side. Further, each of the second lens group and the third lens group includes a three-element cemented lens.

Abstract: An internal focus lens comprising sequentially from an object side 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 second lens group is configured by a simple lens element and is moved along an optical axis to perform focusing. The internal focus lens satisfies condition expressions (1) 0.48<|f3|/f<0.73 and (2) 1.05<Fno×f1/f<1.42, where f3 is the focal length of the third lens group, f is the focal length of the entire optical system, f1 is the focal length of the first lens group, and Fno is the F number of the entire optical system.

Abstract: Provided is a lens barrel having, in order from an object side to an image side, a first to a third group lens, the lens barrel including: a fixed frame; a cam frame supported by the fixed frame so as to be rotationally movable in a optical axis direction between a forward and a backward movement ends; and a shutter frame which moves in the optical axis direction in a rotation restricted state, through the rotation of the cam frame, in which: a third group frame is fixed to the shutter frame so that the object side of the third group lens is arranged on an inner peripheral side of the shutter frame; and the second frame is configured so that the image side of the frame is stored on the inner peripheral side of the shutter frame when the cam frame is positioned at the backward movement end.

Abstract: Embodiments of an optical zoom lens system may comprise three lens groups with a PNP power sequence. The first lens group may vary focus. The second and third lens groups may be movable to vary magnification during zoom. The first lens group may include three lens subgroups with an NNP power sequence: a stationary first lens subgroup, a second lens subgroup including a movable lens element, and a stationary or movable third lens subgroup. The second lens subgroup may include two parts, which may be movable at different rates of travel to vary focus. One part may include the movable lens element. Lens elements of the first lens group may be movable according to different focus movement plans. In the first lens group, lens element movement and lens element power may contribute to provide low focus breathing over the entire zoom range. The F-number may be F/2.8 or less.

Abstract: An optical system includes, in order from an object side, a first lens group having positive refractive power, a second lens group having negative refractive power, and a third lens group having positive refractive power. The second lens group is moved upon carrying out focusing from an infinitely distant object to a close object, at least a portion of the third lens group is moved in a direction including a component perpendicular to an optical axis, and given conditional expressions is satisfied. Accordingly, an optical system excellently suppressing variations in aberrations generated upon vibration reduction, an optical apparatus equipped therewith, and a method for manufacturing the optical system are provided.

Abstract: Provided is an imaging lens, including, in order from an object side: a positive first lens; a second lens having a concave shape toward the object side; and (i?2) number of lens, wherein the i-th lens, which is the most image-side lens, includes: an i-th lens flat plate; and a positive or negative lens element on at least one of the opposite surfaces of the i-th lens flat plate, wherein the following conditional relationship is satisfied: 0.9>Ymax/Y>0.61, where: Ymax is a height of the most off-axial ray on an image-side surface of the (i?1)th lens; and Y is a maximum image height.

Abstract: An immersion type microscope objective lens OL includes, in order from a cover plate C side, a first lens group G1 having positive refractive power, a second lens group G2 having positive refractive power, and a third lens group G3 having negative refractive power. The first lens group G1 includes at least one cemented lens. The second lens group G2 includes at least two achromatic lenses. The third lens group G3 includes, in order from the object side, an achromatic lens CL31 having a strong concave surface facing an image side, and an achromatic lens CL32 having a strong concave surface facing the object side.

Abstract: A lens system with a first group having a positive meniscus lens and a sensor. The optical distance between the front surface of the first group and the sensor can be not greater than the height of the sensor times the image F-number, which may alternatively be referred to as the working F-number. A second group can be disposed adjacent to the front focal point of the first group, and a lens-stop can be disposed adjacent to the second group. A third group can be disposed midway between the lens-stop and the object field of the first and second groups. The image F-number can be 2.8 or greater. The first group can have a doublet formed by a first lens that is plano convex and a second lens that is plano concave. The second group can have a first, plano convex lens and a second, biconvex lens forming a doublet with a third, plano concave lens.

Abstract: A relay finder optical system, of a single-lens reflex camera, includes a condenser lens group, a prism, and a relay lens group, in this order from a primary imaging plane. An image, which is formed on the primary imaging plane, and is upside down and inverted from left to right, is re-formed on a secondary imaging plane for viewing by a photographer. The relay lens group includes a positive front lens group, a negative intermediate lens group, and a positive rear lens group, in this order from the object.

Abstract: Described is a wide-angle slip-on viewfinder (1) on rangefinder cameras for analog and digital wide-angle recordings of different image recording formats with lenses of different focal lengths, comprising three lens groups (LG1, LG2, LG3), a frame/mask unit (10) and a partially transmissive prism cube (8) which is designed as a combination element, wherein, on the light entrance side (4) in the viewfinder beam path (9), a first lens group (LG1) has a negative refractive power and the second and third lens groups (LG2, LG3) have a positive refractive power, wherein the second lens group (LG2) is composed of a first lens (L3) arranged downstream of the first lens group (LG1) and a second lens (L4) arranged on the light exit side (7) and the partially transmissive prism cube (8) is arranged between the lenses (L3, L4) and the third lens group (LG3) is arranged in a mask imaging beam path (11) which is at right angles to the viewfinder beam path (9) between the frame/mask unit (10) and the partially transmissive

Abstract: A fixed-focus lens including a first lens group, a second lens group, and a third lens group is provided. The first lens group has a negative refractive power, includes a plurality of lenses, and is disposed between an object side and an image side. The lenses of the first lens group include at least one aspheric lens. The second lens group is disposed between the first lens group and the image side and has a positive refractive power. The third lens group is disposed between the second lens group and the image side and has a positive refractive power. The third lens group includes a first triple cemented lens and a second triple cemented lens arranged from the object side to the image side in sequence.

Abstract: A third group of lenses is constructed by subsequently arranging those four lenses from an object side to an image side which include a positive lens, a cemented lens of a positive lens and a negative lens, and a positive lens, both of a surface of the third group of the lenses nearest to the object side and a surface of the third group of the lenses nearest to the image side are so aspheric that positive refractive power becomes gradually weaker as a location of the third group of the lenses departs from an optical axis; and a following conditional formula is satisfied: ?0.5<(Y? max/R34I)<0.0 where R34I is a curvature radius of the surface of the third group of the lenses nearest to the image side, and Y? max is a maximum image height.

Abstract: According to various embodiments and aspects of the present invention, there is provided a dynamically tunable thin film interference coating including one or more layers with thermo-optically tunable refractive index. Tunable layers within thin film interference coatings enable a new family of thin film active devices for the filtering, control, modulation of light. Active thin film structures can be used directly or integrated into a variety of photonic subsystems to make tunable lasers, tunable add-drop filters for fiber optic telecommunications, tunable polarizers, tunable dispersion compensation filters, and many other devices.

Abstract: A compact and light-weighted projection lens system that is capable of projecting an image at an angle as wide as 75 degrees with sufficient field angle and brightness as represented by F number of approximately 2.4, that is capable of effectively correcting chroic aberration of magnification and aberration of distortion and exhibiting optical stability against environmental variations, and that is suitable for obtaining an extraordinarily fine image by the magnification and projection.

Abstract: A retrofocus lens system has a negative first, a positive second and a positive third lens group. The first lens group includes an aspheric first lens, a negative meniscus second and third lenses that are convex on the large conjugate side, and a negative meniscus fourth lens being convex on the small conjugate side. The second lens group includes a positive fifth lens and a sixth lens joined to the fifth lens. The third lens group includes a positive meniscus seventh lens being convex on the small conjugate side, a biconcave eighth lens, a positive ninth lens joined to the eighth lens, a biconvex tenth and eleventh lenses, and an aspheric twelfth lens. The system satisfies 0.8<f2/f3<1.5, 1.6<|f1|/f<2.

Abstract: In an image readout lens comprising four lens elements having positive, negative, negative, and positive refracting powers, respectively, the glass material for at least one of the second and third lenses is defined in terms of relative partial dispersion and Abbe number, so as to yield an image readout lens which favorably corrects chromatic aberration and is suitable as a color-image readout lens. Disposed successively from the object side are a first lens L1 made of a positive meniscus lens which is convex toward the object, a second lens L2 and a third lens L3 each having a surface on an image side concave toward the image and a negative refracting power, and a fourth lens L4 made of a biconvex lens, wherein a lens glass material of at least one of the second lens L2 and third lens L3 satisfies the following conditional expression (1): &thgr;g·F+0.0019&ugr;d<0.

Abstract: An objective optical system comprising, in order from the object side, a first lens unit having a positive refractive power, a second lens unit having a negative refractive power and a third lens unit having a positive refractive power, wherein the second lens unit is moved along an optical axis for changing a magnification. This objective optical system is configured to be compact and have favorable optical performance by adequately selecting an airspace between the first lens unit and the second lens unit as well as a power for the first lens unit.

Abstract: A standard lens system composed, in order from the object side, of a first lens unit having a positive refractive power, an aperture stop, a second lens unit having a positive refractive power and a third lens unit having a negative refractive power: the first lens unit being composed of at least one positive meniscus lens component which has a convex surface on the object side, and at least one doublet which consists of a positive meniscus lens component and a negative lens component; the second lens unit being composed of at least one cemented doublet which consists of a negative lens element and a positive lens element, and a positive lens component; and the third lens unit being composed of at least one positive lens component and a negative lens component or at least one negative lens component.

Abstract: An objective lens for an endoscope includes a first lens group having one negative lens, a second lens group having at least one positive lens, and a third lens group including a positive lens. The objective lens satisfies the following relationship:.theta..sub.g,d <-2.223.times.10.sup.-3 .cndot..nu..sub.d +1.365wherein .theta..sub.g,d =(n.sub.g -n.sub.d)/(n.sub.F -n.sub.C), n.sub.g represents the refractive index of the glass material of the first lens group at the g-line, n.sub.d represents the refractive index of the glass material of the first lens group at the d-line, n.sub.F represents the refractive index of the glass material of the first lens group at the F-line, n.sub.C represents the refractive index of the glass material of the first lens group at the C-line, and .nu..sub.d represents the Abbe number of the glass material of the first lens group.

Abstract: Disclosed is a telephoto-type lens system of a head separated charge coupled device (CCD) camera, which includes a first lens group having a positive focal length, a second lens group having a negative focal length, and a third lens group. The first lens group has a first convex lens surface facing an object and an upper convex surface. The third lens group has a second lens with a negative focal length joined to a first lens with a positive focal length. An image angle greater than 29.degree. and high definition images can be achieved with the present invention.

Abstract: A compact objective lens with a diaphragm arranged behind the lens system suitable for use in very compact photographic cameras. The objective lens comprises a plurality of components arranged in a triplet or a triplet type configuration and is capable of covering at least a 55 degree field of view.

Abstract: A compact objective lens system with a diaphragm arranged in front of or preferably behind the lens system and suitable for use in compact photographic cameras. The objective lens comprises a plurality of components arranged in a triplet-type configuration that are capable of covering at least a 55 degree field of view and utilizes the locations of aperture stop, the lens bendings, and the size of lens elements, clear apertures of the lens element surfaces to enhance the lens system performance and to eliminate stray light problems.

Abstract: An achromatic lens system includes in order, from the object side, a front lens group, a chromatic aberration correcting lens group, and a rear lens group. Aberrations, including spherical aberration, coma, astigmatism, curvature of image, as well as axial chromatic aberration of wavelengths from green to red, are substantially corrected by the front lens group and the rear lens group. The axial chromatic aberration of the wavelength blue, caused by the front lens group and the rear lens group, is corrected by the chromatic aberration correcting lens group.

Abstract: An objective lens for an endoscope includes a first lens group having one negative lens, a second positive lens group having at least one positive lens, and a third positive lens group having a cemented lens consisting of one positive lens and a negative lens adhered thereto. The objective lens satisfies the requirements defined by the following relationships:.theta..sub.g,d <-2.223.times.10.sup.-3 .multidot..nu..sub.d +1.365; and,-1.2<f.sub.1 /f<-0.8,wherein .theta..sub.g,d =(n.sub.g -n.sub.d)/(n.sub.F -n.sub.C), n.sub.g represents the refractive index of the glass material of the first lens at the g-line, n.sub.d represents the refractive index of the glass material of the first lens at the d-line, n.sub.F represents the refractive index of the glass material of the first lens at the F-line, n.sub.C represents the refractive index of the glass material of the first lens at the C-line, .nu..sub.d represents the Abbe number of the glass material of the first lens, f.sub.

Abstract: A Fourier transform lens assembly suited for use in an optical information processor includes a first lens group having a positive power, a second lens group having a negative power disposed on one side of the first lens group, and a third lens group having a positive power disposed on the side opposite to the first lens group with respect to the second lens group. The distance between a front focal plane and a back focal plane of the Fourier transform lens assembly is less than two times a focal length of the Fourier transform lens assembly.

Abstract: The invention is directed to a focusing optical system for semiconductor lasers, which is regulated in terms of magnification power in both its directions normal to the optical axis, so that the back focus of sufficient magnitude can be made equal in both the directions and the magnitude of aberration can be regulated to achieve an improvement in focusing efficiency, and in which a light beam from a semiconductor laser having varying exit angles in the horizontal and vertical directions is focused on a spot having substantially equal diameters in the horizontal and vertical directions. This focusing optical system comprises first lens unit L1 including a rotation asymmetric lens having positive power in the direction defined by a large exit angle at which a laser beam emanates from the laser, a second lens unit L2 including at least one lens of negative power, and a third lens unit L3 that is a rotation asymmetric lens unit having positive power in the directions defined by both large and small exit angles.

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 zoom lens for the projector includes, in order from a screen, a first lens unit of positive refractive power, a second lens unit of negative refractive power and a third lens unit of positive refractive power, zooming from the wide-angle end to the telephoto end being performed by axially moving the second and third lens units in such a manner that the air separation between the first and second lens unit increases, while the air separation between the second and third lens units decreases, and the following conditions being satisfied:1<-.beta.3w<1.50.8<-.beta.2w<1.20.25<-f2/fw<0.450.7<e2w/fw<1.1where .beta.2w and .beta.3w are the image magnifications for an infinitely distant object of the second and third lens units in the wide-angle end, respectively, f2 is the focal length of the second lens unit, e2w is the interval between the principal points of the second and third lens units, and fw is the shortest focal length of the entire lens system.

Abstract: The invention relates to an eyepiece that has an improved image surface flatness even at a wider field angle, is well corrected for various aberrations inclusive chromatic aberration of pupil and is usable with inexpensive microscopes (esp., stereoscopic ones). The eyepiece of the invention is an eyepiece including at least three lens components comprising a cemented lens component consisting positive and negative lens elements and a lens component having a negative refractive power in its entirety, characterized in that the lens component other than the lens components proximate to the object and eye sides is provided with a plastic lens element or elements having at least one aspherical surface.