Abstract: An imaging lens is provided and includes, in order from the object side, a front group having a negative power, a stop, and a rear group having a positive power. The front group includes, in order from the object side, a first negative lens having a meniscus shape with a concave surface on an image side, a second negative lens, and a third positive lens. The rear group includes, in order from the object side, a fourth positive lens, a fifth negative lens having a meniscus shape with a concave surface on the object side, and a sixth positive lens. An Abbe number of each of the first lens, the second lens, the fourth lens, and the sixth lens at the d-line is equal to or larger than 40, and an Abbe number of each of the third lens and the fifth lens at the d-line is equal to or smaller than 40. Each lens constituting the front group and the rear group is a single lens.

Abstract: A color image readout lens comprises, in order from an object side: a first group comprising a positive lens convex toward the object side and a biconcave negative lens; a stop; a second group comprising one diffractive optical element that has at least one flat surface and has a diffractive structure formed on the flat surface; and a third group comprising a biconvex positive lens and a negative lens concave toward the object side.

Abstract: An ultra wide-angle imaging lens device 1 includes, in order from an object side: a negative first lens L1 having a meniscus shape with a convex surface directed to the object side; a negative second lens L2 having a concave surface directed to an image side and having at least one aspheric surface; a positive third lens L3 having a convex surface directed to the object side and having at least one aspheric surface; a stop; and a positive fourth lens L4 having a convex surface directed to the image side and having at least one aspheric surface. The following conditional expression (1) is satisfied: ?3.2<L/f34<3.2??(1) where L denotes a distance on an optical axis from an object side surface of the first lens to an image formation surface, and f34 denotes a composite focal length of the third and fourth lenses L3 and L4.

Abstract: A color image readout lens comprises, in order from an object side: a first group comprising a positive lens convex toward the object side and a biconcave negative lens; a stop; a second group comprising one diffractive optical element that has at least one flat surface and has a diffractive structure formed on the flat surface; and a third group comprising a biconvex positive lens and a negative lens concave toward the object side.

Abstract: An ultra wide-angle imaging lens device 1 includes, in order from an object side: a negative first lens L1 having a meniscus shape with a convex surface directed to the object side; a negative second lens L2 having a concave surface directed to an image side and having at least one aspheric surface; a positive third lens L3 having a convex surface directed to the object side and having at least one aspheric surface; a stop; and a positive fourth lens L4 having a convex surface directed to the image side and having at least one aspheric surface. The following conditional expression (1) is satisfied: ?3.2<L/f34<3.2 ??(1) where L denotes a distance on an optical axis from an object side surface of the first lens to an image formation surface, and f34 denotes a composite focal length of the third and fourth lenses L3 and L4.

Abstract: A wide-angle imaging lens is provided and includes: a first lens, a second lens, and a third lens in this order from the object side. The first lens is a negative meniscus and has a convex surface on the object side; the second lens, at least one surface of which is an aspherical surface; and the third lens is a positive lens and has a convex surface on the image side and at least one surface of the third lens is an aspherical surface. The first len is made of a material having an Abbe number of 40 or more and the third lens is made of a material having an Abbe number of 50 or more. An aperture stop is disposed between the second lens and the third lens.

Abstract: A projection optical system is disclosed that includes six lens groups, four of which are positioned in pairs symmetrically about a stop. The second and fifth lens groups, in order from the object side, may be positioned symmetrically about the stop but are also adjustable asymetrically about the stop in order to adjust the magnification of the projection optical system. The first and sixth lens groups, in order from the object side, function to make the projection optical system substantially telecentric on both the object side and the image side, respectively. Also disclosed is a projection and light exposure apparatus that uses the projection optical system of the present invention. The projection and light exposure apparatus automatically detects the image magnification and, based on the detection result, adjusts the positions of the second and fifth lens groups G2 and G5 as a unit so as to maintain a specified magnification.

Abstract: A projection optical system is disclosed that includes six lens groups, four of which are positioned in pairs symmetrically about a stop. The second and fifth lens groups, in order from the object side, may be positioned symmetrically about the stop but are also adjustable asymetrically about the stop in order to adjust the magnification of the projection optical system. The first and sixth lens groups, in order from the object side, function to make the projection optical system substantially telecentric on both the object side and the image side, respectively. Also disclosed is a projection and light exposure apparatus that uses the projection optical system of the present invention. The projection and light exposure apparatus automatically detects the image magnification and, based on the detection result, adjusts the positions of the second and fifth lens groups G2 and G5 as a unit so as to maintain a specified magnification.

Abstract: A projection optical system is disclosed that includes six lens groups, four of which are positioned in pairs symmetrically about a stop. The second and fifth lens groups, in order from the object side, may be positioned symmetrically about the stop but are also adjustable asymetrically about the stop in order to adjust the magnification of the projection optical system. The first and sixth lens groups, in order from the object side, function to make the projection optical system substantially telecentric on both the object side and the image side, respectively. Also disclosed is a projection and light exposure apparatus that uses the projection optical system of the present invention. The projection and light exposure apparatus automatically detects the image magnification and, based on the detection result, adjusts the positions of the second and fifth lens groups G2 and G5 as a unit so as to maintain a specified magnification.

Abstract: A projection optical system that is telecentric or very nearly telecentric on both sides is formed of four positive lens groups with a central diaphragm for achieving at least very nearly unity magnification. The second and third lens groups are movable along the optical axis of the projection optical system, preferably at the same rate and in the same direction, in order to vary the magnification of the projection optical system. The range of movement of the second and third lens groups includes a position where the first and second lens groups together are a mirror image about the plane of the diaphragm of the third and fourth lens groups together. A projection exposure device uses the projection optical system to form an image of an illuminating beam modulated by a mask pattern on a workpiece. An image magnification detector controls movement of the second and third lens groups.

Abstract: A projection optical system that is telecentric or very nearly telecentric on both sides is formed of four positive lens groups with a central diaphragm for achieving at least very nearly unity magnification. The second and third lens groups are movable along the optical axis of the projection optical system, preferably at the same rate and in the same direction, in order to vary the magnification of the projection optical system. The range of movement of the second and third lens groups includes a position where the first and second lens groups together are a mirror image about the plane of the diaphragm of the third and fourth lens groups together. A projection exposure device uses the projection optical system to form an image of an illuminating beam modulated by a mask pattern on a workpiece. An image magnification detector controls movement of the second and third lens groups.

Abstract: A projection optical system is disclosed that includes six lens groups, four of which are positioned in pairs symmetrically about a stop. The second and fifth lens groups, in order from the object side, may be positioned symmetrically about the stop but are also adjustable asymetrically about the stop in order to adjust the magnification of the projection optical system. The first and sixth lens groups, in order from the object side, function to make the projection optical system substantially telecentric on both the object side and the image side, respectively. Also disclosed is a projection and light exposure apparatus that uses the projection optical system of the present invention. The projection and light exposure apparatus automatically detects the image magnification and, based on the detection result, adjusts the positions of the second and fifth lens groups G2 and G5 as a unit so as to maintain a specified magnification.

Abstract: A collimator lens comprises, successively from a parallel luminous flux side, a first lens having a positive refracting power, second and third lenses having a negative composite refracting power, a fourth lens having a positive refracting power, and a fifth lens having a positive refracting power. The second and third lenses are cemented together. One of the second and third lenses has a negative refracting power, whereas the other has a positive refracting power. The collimator lens further satisfies Bƒ/ƒ>0.6, where Bf is the back focus of the whole lens system, and f is the focal length of the whole lens system.

Abstract: A collimator lens comprises, successively from a parallel luminous flux side, a first lens having a positive refracting power, second and third lenses having a negative composite refracting power, a fourth lens having a positive refracting power, and a fifth lens having a positive refracting power. The second and third lenses are cemented together. One of the second and third lenses has a negative refracting power, whereas the other has a positive refracting power. The collimator lens further satisfies Bƒ/ƒ>0.6, where Bf is the back focus of the whole lens system, and f is the focal length of the whole lens system.

Abstract: An imaging lens comprises, successively from an object side, a positive first lens L1 having a convex surface directed onto the object side, a negative second lens L2 having a concave surface directed onto an image side, a third lens L3 of a positive meniscus form having a convex surface directed onto the object side, a fourth lens L4 of a positive meniscus form having a convex surface directed onto the image side, a negative fifth lens L5 having a concave surface directed onto the object side, and a positive sixth lens L6 having a convex surface directed onto the image side, the first lens L1 and the second lens L2 being cemented to each other, the imaging lens satisfying the following conditional expressions: 0.51<f34/f<0.72 0.83<f1/f6<1.17 1.17<(v1×v3)½/v2<1.

Abstract: An imaging lens comprises, successively from an object side, a positive first lens L1 having a convex surface directed onto the object side, a negative second lens L2 having a concave surface directed onto an image side, a third lens L3 of a positive meniscus form having a convex surface directed onto the object side, a fourth lens L4 of a positive meniscus form having a convex surface directed onto the image side, a negative fifth lens L5 having a concave surface directed onto the object side, and a positive sixth lens L6 having a convex surface directed onto the image side, the first lens L1 and the second lens L2 being cemented to each other, the fifth lens L5 and the sixth lens L6 being cemented to each other, the imaging lens satisfying the following conditional expressions: 0.01<d6/f<0.17 0.9<f3/f<1.8 −0.4<f/f12<0.4 0.51<f34/f<0.72 1.15<v1/v2<1.

Abstract: A bright image readout lens having a wider angle of view comprises, successively from the object side, a first lens L1 made of a positive meniscus lens having a convex surface directed onto the object side, a second lens L2 made of a biconcave lens, a third lens L3 made of a biconvex lens, and a fourth lens L4 made of a negative meniscus lens having a convex surface directed onto the imaging surface side, wherein at least one surface in at least one of the first lens L1 and third lens L3 is an aspheric surface, and wherein a stop is disposed between the second lens L2 and the third lens L3. This image readout lens favorably corrects various kinds of aberration.

Abstract: In a three-sheet image readout lens, predetermined expressions are satisfied, so as to yield a bright lens system which can favorably correct each kind of aberration, while attaining a smaller size and a lighter weight. The lens system is constituted by, successively from the object side, three positive, negative, and positive lenses L.sub.1 to L.sub.3, while a stop i is disposed downstream the third lens L.sub.3, satisfying the following conditional expressions (1) to (6):(1) 0.85<f.sub.1 /f<0.93(2) -0.90<f.sub.2 /f.sub.3 <-0.84(3) 0.025<d.sub.2 /f<0.043(4) 0.09<d.sub.5 /f<0.16(5) -2.5<r.sub.3 /r.sub.4 <-2.1(6) .vertline.d.sub.6 .vertline./f.ltoreq.0.03.

Abstract: A collimator lens comprises, successively from a parallel luminous flux side, a positive lens, a cemented lens made of negative and positive lenses, a positive lens, and a negative lens, and satisfies a predetermined conditional expression, whereby, when carrying out multi-beam scanning, various kinds of aberration, such as image surface curvature amount in particular, are greatly reduced with respect to the respective light beams from individual light sources. Successively disposed from the parallel luminous flux side are a first lens L.sub.1 made of a biconvex lens having a surface with a stronger curvature directed onto the parallel luminous flux side, a second lens L.sub.2 made of a biconcave lens having a surface with a stronger curvature directed onto the parallel luminous flux side, a third lens L.sub.3 made of a biconvex lens having a surface with a stronger curvature directed onto the light source side, a fourth lens L.sub.

Abstract: Positive first and second lenses each having a convex surface directed onto the object side, a negative third lens having a concave surface directed onto an image side, a negative fourth lens having a concave surface directed onto the object side, and positive fifth and sixth lenses each having a convex surface directed onto the image side are successively disposed from the object side, and predetermined conditional expressions are satisfied, thus yielding an image readout imaging lens suitable for reading out color originals. Successively from the object side, positive first and second lenses L1 and L2 each having a convex surface directed onto the object side, a negative third lens L3 having a concave surface directed onto an image side, a negative fourth lens L4 having a concave surface directed onto the object side, and positive fifth and sixth lenses L5 and L6 each having a convex surface directed onto the image side are disposed, and the following conditional expressions (1) to (6) are satisfied:Nda+0.