Abstract: A micro lens assembly for short-range imaging, in order from the object side to the image side: a flat panel, a first lens group, a stop, a second lens group, and an IR cut filter. Wherein a focal length of the first lens group combined is LF, a focal length of the second lens group combined is RF, a distance from an object to be imaged to an object-side surface of a first lens element of the first lens group along an optical axis is OTL, a distance from the object to be imaged to an image plane along the optical axis is TTL, and they satisfy the relations: LF>0; RF>0; 0.65<LF/RF<1.25; OTL<2.0 mm; TTL<10 mm Such a lens assembly can obtain higher short-range imaging effect while maintaining its miniaturization and can reduce the aberration in short-range imaging.

Abstract: A zoom lens includes a negative first lens group, a positive second lens group, and a subsequent lens group in order from an object side. A focusing lens group closer to an image side than the first lens group moves during focusing. The first lens group consists of a first-a lens group and a first-b lens group in order from the object side. Assuming that an average of refractive indices of the negative lenses of the first-a lens group is Nd1ave, a focal length of the focusing lens group is ff, and a focal length of the first lens group is f1, Conditional Expression (1) of 1.73<Nd1ave<1.95 and Conditional Expression (2) of 1<|ff/f1|<3 are satisfied.

Abstract: A zoom lens includes a negative first lens group, a positive second lens group, and a subsequent lens group in order from an object side. A focusing lens group closer to an image side than the first lens group moves during focusing. The first lens group consists of a first-a lens group and a first-b lens group in order from the object side. Assuming that an average of refractive indices of the negative lenses of the first-a lens group is Nd1ave, a focal length of the focusing lens group is ff, and a focal length of the first lens group is fl, Conditional Expression (1) of 1.73<Nd1ave<1.95 and Conditional Expression (2) of 1<|ff/f1|<3 are satisfied.

Abstract: The lens device includes a zoom lens and a controller. A focusing lens group which moves during focusing and an aberration correction lens group having a refractive power lower than a refractive power of the focusing lens group having the lowest refractive power are disposed within the zoom lens. The controller adjusts a position of the aberration correction lens group relative to the focusing lens group of which focus sensitivity is maximized for each zoom position according to the changed condition.

Abstract: An imaging apparatus in an embodiment includes lens optical systems each including a lens whose surface closest to the target object is shaped to be convex toward the target object, imaging regions which respectively face the lens optical systems and output a photoelectrically converted signal corresponding to an amount of light transmitting the lens optical systems and received by the imaging regions, and a light-transmissive cover which covers an exposed portion of the lens of each of the lens optical systems and a portion between the lens of one of the lens optical systems and the lens of another one of the lens optical systems adjacent to the one of the lens optical systems, the cover having a curved portion which is convex toward the target object. The optical axes of the lens optical systems are parallel to each other.

Abstract: The present disclosure discloses a camera optical lens. The camera optical lens includes, in an order from an object side to an image side, a first lens, a second lens having a positive refractive power, a third lens having a positive refractive power, a fourth lens, a fifth lens, and a sixth lens. The first lens is made of glass material, the second lens is made of plastic material, the third lens is made of plastic material, the fourth lens is made of glass material, the fifth lens is made of plastic material, and the sixth lens is made of plastic material. The camera optical lens further satisfies specific conditions.

Abstract: An imaging optical system includes, in order from an object side to an image side, a first lens group having negative optical power, a second lens group having positive optical power, a third lens group having negative optical power, and a fourth lens group with negative optical power. A lens disposed closest to the object side in the second lens group has a concave surface directed toward the object side, and a lens disposed closest to the object side in the fourth lens group has positive optical power. Each distance between the lens groups changes when zooming from a wide-angle end to a telephoto end on photographing.

Abstract: The zoom lens is a lens system that forms an intermediate image, and includes, in order from the magnification side: a first lens group that remains stationary during zooming; a plurality of movable lens groups that move during zooming; and a final lens group that has a positive power and remains stationary during zooming. Two or more movable lens groups are positioned to be closer to the reduction side than the intermediate image. The lens system closer to the reduction side than the intermediate image includes, in order from the magnification side, a front group and a rear group. The zoom lens satisfies predetermined conditional expressions (1) and (2) relating to the rear group.

Abstract: A zoom lens comprising a plurality of lens units, in which a distance between adjacent lens units is variable in a magnification variation. The plurality of lens units include, in order from an enlargement conjugate side to a reduction conjugate side, a first lens unit that has a negative refractive power and that is fixed for the magnification variation, a second lens unit, a third lens unit, a fourth lens unit, a fifth lens unit, a sixth lens unit, and a seventh lens unit, each of which moves for the magnification variation, and an eighth lens unit that has a positive refractive power and that is fixed for the magnification variation.

Abstract: A laser beam expander has at least two negative lenses with adjustable collimation. The amount of required motion can be reduced by an order of magnitude over single negative lens approaches by splitting the input lens in two and adjusting the small remaining air gap between the lenses. The change in collimation may be accomplished by heating/cooling (i.e., thermal), mechanical motion (e.g., motors), electro-optical means (e.g., applying or reducing an electric current), any combination thereof, or any other suitable mechanism.

Abstract: A projection optical system is constituted by, in order from the reduction side, a first optical system for forming an image displayed by image display elements as an intermediate image, a first optical path bending means that bends an optical path with a reflective surface, and a second optical system for forming the intermediate image on a magnification side conjugate plane. The second optical system is constituted by, in order from the reduction side, a first lens group having a positive refractive power, a second optical path bending means that bends an optical path with a reflective surface, and a second lens group having a positive refractive power. Conditional Formulae (1) and (2) below are satisfied. 10.0<TL1/|f|<50.0??(1) 4.0<TL21/|f|<30.0??(2).

Abstract: A imaging lens assembly includes, in order from an object side to an image side, a first lens element, a second lens element, a third lens element, a fourth lens element, a fifth lens element and a sixth lens element. The first lens element has negative refractive power. The second lens element has positive refractive power. The third lens element has positive refractive power. The fourth lens element has positive refractive power. The fifth lens element has positive refractive power. The sixth lens element has negative refractive power. The imaging lens assembly has a total of six lens elements.

Abstract: A polarization image sensor includes: photodiodes arranged on an image capturing plane; a color mosaic filter in which color filters in multiple different colors are arranged to face the photodiodes; an optical low-pass filter which covers the color mosaic filter; and polarization optical elements located closer to a light source than the optical low-pass filter is. Each polarization optical element covers an associated one of the photodiodes and makes light which is polarized in a predetermined direction in a plane that is parallel to the image capturing plane incident onto the optical low-pass filter. The color filters are arranged so that light that has passed through polarization optical elements is transmitted through an associated one of the color filters in a single color. Each color filter covers multiple photodiodes.

Abstract: A projection lens is provided having a positive refractive power as a whole and including a correction group consisting of a plurality of lens groups that corrects field curvature by moving in an optical axis direction and changing the distance between each lens group. The conjugation length of a combined optical system combining the most magnification side lens group constituting the correction group to the most reduction side lens group constituting the correction group in the projection lens is constant before and after the movement of the correction group for correcting field curvature. If the projection lens is variable in magnification or focusable by moving at least some of the lens groups, the movement of the correction group for correcting field curvature is allowed to be performed independently of the movement for either changing magnification or focusing.

Abstract: A negative first lens group, a positive second lens group, a negative third lens group, a positive fourth lens group, a negative fifth lens group, and a positive sixth lens group are disposed in this order from the magnification side. The reduction side is made telecentric. While changing magnification, the second lens group through the fifth lens group are moved, and the first lens group and the sixth lens group are fixed. Predetermined conditional expressions are satisfied.

Abstract: A zoom lens and optical apparatus includes, in order from a magnification conjugate side, a first lens unit that has a positive refractive power and is fixed during magnification variations, and a magnification-variable unit configured to move for magnification variations. The first lens unit includes, in order from the magnification conjugate side, a first lens sub-unit that has a positive refractive power and is configured to move during focusing, and a second lens sub-unit that has a positive refractive power and moves during focusing. The first lens sub-unit and the second lens sub-unit move and reduce an interval between the first lens sub-unit and the second lens sub-unit for focusing from infinity to a close end. A surface of the second lens sub-unit closest to the magnification conjugate side has a concave shape on the magnification conjugate side.

Abstract: A zoom lens system used in a spectrum region including visible light has movable lens groups moved for zooming, and has, in a movable lens group, a negative lens element made of a material fulfilling the conditional formulae Vd<55 and 0.0018×Vd+P<0.65 and, in a movable lens group, a positive lens element made of a material fulfilling the conditional formulae 60<Vd, 0.645<0.0018×Vd+P, and 9×10?6<dN/dT, where Vd is the Abbe number for a d-line; P=(Ng?NF)/(NF?NC); Ng, NF, and NC are the refractive indices for the g-, F-, and C-lines respectively; and dN/dT is the variation rate in refractive index accompanying variation in room temperature. The negative and positive lens elements move in the same direction during zooming.

Abstract: Providing a zoom lens system having a high zoom ratio being compact with high optical performance. The system includes, in order from an object along an optical axis, a first lens group G1 having positive refractive power, a second lens group G2 having negative refractive power, at least one lens group having positive refractive power, and an n-th lens group GN being disposed to the most image side. The n-th lens group GN with positive refractive power includes, in order from the object, a front group GNa and a rear group GNb having positive refractive power. Focusing on an object is carried out by moving the rear group GNb along the optical axis, and a given conditional expression is satisfied.

Abstract: To provide an image forming optical system that can achieve good correction of chromatic aberration, which is seriously needed particularly when the zoom ratio is high, while achieving slimness and a high zoom ratio and to provide an electronic image pickup apparatus equipped with such an image forming optical system, an image forming optical system has a lens group A including a lens component made up of a positive lens LA and a negative lens LB cemented together and having a negative refracting power as a whole. The lens group A is arranged between a lens group I closest to the object side and an aperture stop. The distance between the lens group I and the lens group A changes for zooming. The lens component has an aspheric cemented surface, and a certain condition concerning the shape of the aspheric surface is satisfied.

Abstract: A zoom lens and optical apparatus includes, in order from a magnification conjugate side, a first lens unit that has a positive refractive power and is fixed during magnification variations, and a magnification-variable unit configured to move for magnification variations. The first lens unit includes, in order from the magnification conjugate side, a first lens sub-unit that has a positive refractive power and is configured to move during focusing, and a second lens sub-unit that has a positive refractive power and moves during focusing. The first lens sub-unit and the second lens sub-unit move and reduce an interval between the first lens sub-unit and the second lens sub-unit for focusing from infinity to a close end. A surface of the second lens sub-unit closest to the magnification conjugate side has a concave shape on the magnification conjugate side.

Abstract: An imaging optical system is capable of arranging right and left optical systems parallel to each other while maintaining advantages of an inwardly inclined system stereoscopic microscope apparatus including right-eye and left-eye optical paths completely independent of each other, as well as a microscope apparatus including the imaging optical system. The imaging optical systems each include a plurality of lens groups and variable power optical systems. At least one lens group of the plurality of lens groups is arranged such that a center thereof deviates by a predetermined amount in a direction perpendicular to the optical axis, and a second lens group of each of the variable power optical systems is moved in a direction including a component perpendicular to a reference optical axis, in at least part of a power changing section from a high-power end state to a low-power end state.

Abstract: An objective lens system includes a first lens group having a focal length F1 for focusing, a second lens group, which is a system of magnification variation having a focal length F2, a third lens group for compensation and having a focal length F3 and a fourth lens group having a focal length F4. The first lens group has a positive first lens assembly with a focal length F1a and a negative second lens assembly with a focal length F1b. The third lens group ensures an image point of the second lens group falls within the focal length F3 thereof. The first, second, third and fourth lens groups commonly form a finite conjugative system of magnification variation. Moreover, the objective lens system, as a whole, has a negative focal length.

Abstract: A lens barrel includes a fourth lens, a prism, and a sixth lens. The fourth lens receives a light flux incident along a first optical axis. The prism includes a reflecting surface reflecting the light flux passing through the fourth lens to a direction along a second optical axis intersecting with the first optical axis. The sixth lens receives the light flux reflected by the prism. A second group frame includes an opening portion, a prism retaining frame that is arranged in a more inner position than the opening portion and in which the prism is contained, and a plurality of adhesive pockets arranged on an area around the prism retaining frame and being open to the side of the opening portion. Adhesive agent is filled in the adhesive pockets.

Abstract: Zoom lens systems and methods for imaging incoming rays over a range of ray angles are disclosed. The incoming rays are characterized by at least phase. The zoom lens system includes an optical axis and is characterized by a plurality of modulation transfer functions (MTFs) corresponding at least to the range of ray angles. The zoom lens system includes an optical group disposed along the optical axis, including at least one variable optical element that has a variable focal length selectable between at least two distinct focal length values. The optical group also includes a wavefront coding element. The wavefront coding element alters at least the phase of the incoming rays, such that the plurality of MTFs corresponding to the range of ray angles, for each one of the two distinct focal length values, are less sensitive to misfocus-like aberrations than a corresponding system without the wavefront coding element.

Abstract: An object is to provide a laser light irradiation apparatus and a laser light irradiation method which reduce errors of an irradiation position of laser light to an irradiated object and allow irradiation with laser light of any size when the irradiated object is irradiated with the laser light through a beam expander optical system. One feature of a laser light irradiation apparatus of the present invention is to include a laser oscillator; a beam expander optical system having a zoom function; and a correction lens disposed to conjugate the laser oscillator and the beam expander optical system including at least a first lens, a second lens, and a third lens in order in a traveling direction of the laser light, wherein the second lens and the third lens are cooperated with each other in accordance with the magnification of the laser light.

Abstract: A projection zoom lens is provided and includes: in order from the magnification side, a positive first lens group performing focusing with being fixed during power-varying and having a focusing function; a negative second lens group, a negative third lens group, and a positive fourth lens group, which are moved with correlation during the power-varying; and a positive fifth lens group G5 fixed during the power-varying. An aperture diaphragm is fixed between the fourth lens group and the fifth lens group during the power-varying. In addition, the expression of 1.7<Bf/f<3.0 is satisfied, where f is a focal length of the whole system, and Bf is a back focal length (air conversion distance) of the whole system.

Abstract: A compact zoom lens which projects an image from a DMD on to a screen in an enlarged scale is provided. There is provided a zoom lens including, in order from a magnifying side, a first lens group having a positive or negative refractive power as a whole, a second lens group having a negative refractive power as a whole, a third lens group having a positive or negative refractive power as a whole, a fourth lens group having a positive refractive power as a whole and a fifth lens group having a positive refractive power as a whole, wherein a variable power as a whole lens system of the zoom lens is established by configuring such that the first lens group and the fifth lens group are left fixed, the second lens group, the third lens group and the fourth group are made to move on an optical axis.

Abstract: A projection zoom lens has three negative, positive, and position group configuration in order from a magnification side. A first group G1 includes a positive L1, a negative meniscus lens L2, a negative lens L3, a positive L4, and a negative lens L5. The positive lens L4 and the negative lens L5 constitute a cemented lens. The second group G2 includes a biconvex lens L6 and a biconvex lens L7. The third group G3 includes an aspheric lens L8, a negative lens L9, a positive lens L10, and a positive lens L11. The first to third lens groups satisfy: |M3/f3|<|M1/f1|<|M2/f2|??(1) 0.40<|M2/f2|<0.80??(2) where Mi denotes a movement amount of the i-th lens group between the wide-angle end and the telephoto end during the varying of the power, and fi denotes a focal length of the i-th lens group.

Abstract: A zoom lens telecentric on a reduction side includes a first negative lens, a second negative lens and a first positive lens arranged from the enlargement side to the reduction side. At least one of the first and second negative lenses has an aspherical surface. The zoom lens satisfies ?f12/fw<1.4, ?f12/(Hwpn?f12)<0.6 and |dn/dt|<1.0×10?5, where f12 is the focal length of the combined optical system composed of the first and second negative lenses, Hwpn is the distance from the rear principal point of the combined optical system composed of the first and second negative lenses to the front principal point of the first positive lens, dn/dt is a change in the refractive index of the material of which said one negative lens is made relative to a change in its temperature from 25° C., and fw is the focal length of the entire lens system at the wide angle end.

Abstract: A projection zoom lens includes, in order from an enlargement side, a first lens unit G1 of negative refracting power, a second lens unit G2 of positive refracting power and a third lens unit G3 of positive refracting power. Focusing is implemented by movement of the first lens unit G1 alone. The first lens unit satisfies condition (1) with respect to its movement. 0.003<?d/|f1|<0.030??(1) Here f1 is the focal length of the first lens unit, and ?d is the maximum displacement of the first lens unit as measured from a wide-angle end position thereof upon zooming from the wide-angle end to the telephoto end with a projected image focusing at a constant distance.

Abstract: A zoom optical system includes in order from a reduction side to a magnification side: a first lens unit having a positive optical power; a second lens unit having a negative optical power; a third lens unit having a positive optical power; and a fourth lens unit having a positive optical power, wherein respective intervals between the above described first, second, third and fourth lens units vary during zooming; a magnification-side conjugate position with respect to a reduction-side conjugate position and a position of a pupil of the above described zoom optical system with respect to a reduction-side conjugate position are substantially immobile respectively across the entire zooming range, and the above described fourth lens unit moves toward the magnification side and an interval between the above described first lens unit and the above described fourth lens unit increases during zooming from a wide-angle end to a telephoto end.

Abstract: A zoom lens includes, in sequence from the object side: a first lens group with an overall negative refractive power; and a second lens group with an overall positive refractive power. A zoom factor changes by moving the second lens group. Focal adjustments are made by moving the first lens group accompanied by the change of the zoom factor made by the movement of the second lens group. The first lens group includes a first lens having a negative refractive power and a second lens having a positive refractive power. The second lens group includes a third lens having a positive refractive power, a fourth lens with a positive refractive power and a fifth lens with a negative refractive power bonded together, and a sixth lens with a positive refractive power. The bonded lenses form a meniscus shape with a convex surface facing the object side. The resulting lens is short in length, compact, thin, and suitable for digital still cameras.

Abstract: A zoom optical system includes, in order from the reduction conjugate side to the magnification conjugate side, a first lens unit having a positive optical power; a second lens unit having a negative optical power; a third lens unit having a positive optical power; and a fourth lens unit having a negative optical power, wherein in an entire zoom range, a magnification-side conjugate position relative to a reduction-side conjugate position, and the position of a pupil of the zoom optical system relative to the reduction-side conjugate position are each substantially fixed, and the interval between the first lens unit and the second lens unit at a telephoto end is larger than the interval between the first lens unit and the second tens unit at a wide-angle end.

Abstract: An ultra wide angle zoom lens for a projection display system including a liquid crystal panel displaying an image; a second lens group having a positive refractive power, formed by combination of two or more lenses, and correcting chromatic and spherical aberrations of incident light from the liquid crystal panel; a total reflection mirror reflecting the incident light from the second lens group in a predetermined direction; and a first lens group having a negative refractive power, formed by combination of two or more lenses, and correcting distortion and astigmatism of the incident light from the total reflection mirror. Here, a projection lens is constructed so that a magnification of the projection lens is adjusted by movement of the second lens group along an optical axis, and the first lens group is moved forward and backward according to the adjusted magnification of the projection lens so that lens focusing can be adjusted.

Abstract: Provided is a projection lens, including: a plurality of moving lens units that move on an optical axis for zooming; and a plurality of plastic lenses containing plastic, in which when a focal distance of an i-th positive lens from a predetermined plane side of N positive lenses of the plurality of plastic lenses is given by fpi, a focal distance of a j-th negative lens from the predetermined plane side of M negative lenses of the plurality of plastic lenses is given by fnj, and fp and fn are defined by 1 fp = ? i = 1 N ? 1 fpi 1 fn = ? j = 1 M ? 1 fnj (N and M each are a natural number, that is, an integer equal to or larger than 1), ?0.56<fn/fp<?0.05 is satisfied.

Abstract: A compact zoom lens system includes, from the object side to the image side, a negative first lens group (1), a positive second lens group (2), a positive third lens group (3) and a positive fourth lens group (4). The first lens group is stationary, and both the second and third lens groups are movable for effecting focal length change. The fourth lens group is also movable to compensate for image plane shift due to focal length change and thereby maintain the position of the image plane. The compact zoom lens system has a significantly reduced lens count and thus has an overall length of only 20 mm while achieving an approximately 3× zoom ratio. Sufficient back focal length is ensured even for such a short overall length. By employing aspheric lenses (10, 20, 301, 31, 41) for aberration correction, a high level of optical performance can be ensured.

Abstract: The invention relates to an expensive zoom lens that has a zoom ratio of as high as about 5 and high optical performance and is very thin in its depth direction. With the invention, the optical path of the optical system is easily bendable by means of a reflecting optical member. The zoom lens includes a first lens group G1 having positive power, a second lens group G2 having negative power, a third lens group G3 having positive power and a fourth lens group G4 having positive power, and comprises five lens groups in all. The first lens group G1 comprises, in order from its object side, a lens component of negative refracting power, an optical path-bending reflecting optical member P and a lens component of positive refracting power.

Abstract: A zoom optical system provided, in order from a reduction side toward a magnification side, with: a first lens unit having positive optical power; a second lens unit having positive optical power; a third lens unit having positive optical power; and a fourth lens unit having negative optical power; wherein the interval between adjacent ones of the first, second, third and fourth lens units is varied during zooming, and in an entire zooming range, a magnification side conjugate position relative to a reduction side conjugate position, and the position of the pupil of the zoom optical system relative to the reduction side conjugate position are substantially immovable.

Abstract: A variable magnification optical system for forming an optical image of an object on the light-receiving surface of an image sensor with variable magnification includes: from an object side, a first lens unit having a positive optical power, a second lens unit having a negative optical power, a third lens unit having a positive optical power, a fourth lens unit having a positive optical power, and a fifth lens unit. In magnification variation from the wide-angle end to the telephoto end, the first lens unit, the third lens unit, and the fifth lens unit are kept in fixed positions whereas the second lens unit and the fourth lens unit move. The third lens unit includes, from the object side, a positive lens element having a biconvex form, and a negative lens element having a form concave to an image side. The negative lens element has an aspherical surface.

Abstract: A telephoto lens includes, in order from the object side, a first lens unit having a positive refracting power, a second lens unit having a negative refracting power, a third lens unit having a positive refracting power, and a fourth lens unit having a negative refracting power. The second lens unit has a cemented lens composed of a positive lens and a negative lens, and a negative lens. The fourth lens unit has a cemented lens composed of a negative lens and a positive lens, and a negative lens. The telephoto lens satisfies the following conditions: ?d>80 ?0.5>f4/f>?1.2 where ?d is an Abbe's number of a lens having a positive refracting power in the first lens unit, f4 is a focal length of the fourth lens unit, and f is a focal length of the entire optical system.

Abstract: A zoom system that is particularly suited to use on an illumination device of a microlithographic projection exposure system and is configured in the form of a focal-length-zooming lens. The lenses of the zoom system define an object plane (6) and an image plane (8) that is a Fourier transform of the object plane. Both an intermediate pupillary plane (25) that is conjugate to the image plane and an intermediate field plane (27) that is a Fourier transform of the image plane lie between the object plane (6) and image plane (8). At least one movable lens (31, 32) is arranged in the vicinity of these intermediate image planes (25, 27). The system is characterized by a large expansion of the illuminated area on the image plane for short lengths of travel and light weights of these movable lenses (31, 32).

Abstract: The invention provides a zoom lens device that can include lens groups. A third lens group (compensator lens group) can be disposed between two lens groups (a second and a fourth lens groups) forming a variator lens group. The two lens groups (the second and fourth lens groups) forming the variator lens group can be retained by a common variator-lens frame and moved together. Accordingly, a zoom lens device, an optical apparatus, and a projector can be provided in which, even when a plurality of lens groups are assembled, degradation of optical characteristics due to decentering between the lens groups can be prevented.

Abstract: Projection lenses for use with pixelized panels (PP) are provided. The projection lenses have a negative first unit (U1) separated from a positive second unit (U2) by a reflective surface (RS) which folds the lens' optical axis. The lenses are telecentric on the short conjugate side, have a large field of view in the direction of the long conjugate, and have low aberration levels, including, in particular, low levels of lateral color.

Abstract: A projection objective having a variable focal length, preferably serving to image tilting mirror matrices or reflecting and/or transmitting LCDs, said projection objective comprising three groups of lenses (G1, G1, G3) arranged on a common optical axis, wherein, starting from the side facing the projection screen, the first lens group (G1), serving the purpose of focussing, and the second lens group (G2), serving the purpose of varying the focal length, are arranged on the optical axis in a variably positioned manner, and the third lens group (G3) is stationary. According to the invention, the following condition is met: 1.0 h max<dG2-G3<1.5 h max and s?10 mm, wherein h max is the maximum object height, dG2-G3 is the distance between the lens group G2 and the lens group G3 in a first position, and s is the object-side intercept distance or distance from the vertex to the object.

Abstract: An imaging optical system has a variable magnification optical system. The variable magnification optical system includes, in order from the object side, a first lens unit with positive refractive power, a second lens unit with positive refractive power, a third lens unit with negative refractive power, a fourth lens unit with positive refractive power, and an aperture stop interposed between the third lens unit and the fourth lens unit. The variable magnification optical system changes an imaging magnification while keeping an object-to-image distance constant. The imaging magnification is changed by varying spacing between the first lens unit and the second lens unit, spacing between the second lens unit and the third lens unit, and spacing between the third lens unit and the fourth lens unit. When the imaging magnification is changed, the imaging optical system satisfies the following conditions in at least one variable magnification state: |En|/L>0.

Abstract: An image forming optical system includes, comprises, in order from the object side toward the image side, a first lens unit with positive refracting power, a second lens unit with positive refracting power, a third lens unit with negative refracting power, a fourth lens unit with positive refracting power, and an aperture stop interposed between the third lens unit and the fourth lens unit. The image forming optical system has a variable magnification optical system in which spacings between these lens units are changed to vary the imaging magnification, changes the imaging magnification while constantly keeping the object-to-image distance of the image forming optical system, and in at least one variable magnification state where the imaging magnification is changed, satisfies the following conditions: |En|/L>0.4 |Ex|/|L/&bgr;|>0.

Abstract: A projection zoom lens includes a first lens group having a negative refracting power, a second lens group having a positive refracting power, a third lens group having a negative refracting power, and a fourth lens group having a positive refracting power, which are arranged in that order from a screen side toward an image plane side along an optical axis. The first and the fourth lens group are kept stationary, and the second and the third lens group are moved along the optical axis to vary power from a limit wide angle power toward a limit telephoto power. The second lens group includes a 2nd-group 1st positive lens, a 2nd-group 1st compound lens formed by joining a 2nd-group 2nd positive lens having a convex surface on the image plane side and a 2nd-group 1st negative lens having a concave surface on the screen side, and a 2nd-group 3rd positive lens arranged in that order from the screen side toward the image plane side.

Abstract: A zoom lens, comprises: three lens groups including a first lens group having a negative refracting power, a second lens group having a positive refracting power and a third lens group having a positive refracting power arranged serially in this order from the object side. The second lens group comprises a positive lens, a cemented lens including a positive lens and a negative lens and one lens arranged serially in this order from the object side.

Abstract: An optical system of a composite camera including a first image-forming optical system, a second image-forming optical system, and a condenser lens group, which includes two or more lens elements, or includes a single lens element on which at least one aspherical surface is formed; and at any image height on the equivalent image plane, the following condition is satisfied: &Dgr;&thgr;Pmax−&Dgr;&thgr;Pmin<2° . . .

Abstract: A projection optical system of the present invention has a first lens group G1 being positive, a second lens group G2 being negative, a third lens group G3 being positive, a fourth lens group G4 being negative, a fifth lens group G5 being positive, and a sixth lens group G6 being positive in the named order from the first object toward the second object, in which the second lens group G2 comprises an intermediate lens group G2M between a negative front lens L2F and a negative rear lens L2R and in which the intermediate lens group G2M is arranged to comprise at least a first positive lens being positive, a second lens being negative, a third lens being negative, and a fourth lens being negative in the named order from the first object toward the second object.