Abstract: A wide angle projection lens includes, in sequential order from an image side, a first lens group of negative refractive power, the first lens group having at least one aspheric surface, a second lens group, and a third lens group of positive refractive power. For the wide angle projection lens, the following Conditions (1) to (4) are satisfied: |F1/F|?4.5 (Condition (1)); 2.5?|F2/F|?6.0 (Condition (2)); 3.8?|F3/F|?5.0 (Condition (3)); and 0.8?BFL/F?1.4 (Condition (4)). An optical engine, including the wide angle projection lens, can be implemented in a projection display device.

Abstract: The compact imaging assembly has an electronic imager and an objective lens with a focal length fo. The objective lens receives light and forms an image of the object on the imager's image plane. The image plane has a maximum effective dimension DI. The objective lens has a first lens group comprising two to three elements with an object surface facing the object and an image surface facing an image plane. The objective lens also has a middle lens element with a concave object surface that is facing the lens group image surface, and a final lens element that has a positive power. The distance from the lens group object surface to the image plane is TT. The lens group, the middle lens and the final lens elements are coaxially aligned and on an optical axis normal to the image plane.

Abstract: A subminiature optical system used in a subminiature image sensor module is provided. The subminiature optical system has a first lens group, a second lens group and a third lens group sequentially arranged from the object side. The first lens group has a first lens of plus refractive power and a second lens of minus refractive power, the second lens being cemented to the first lens. The second lens group has a third lens where at least one refraction surface is aspherical and has minus refractive power. The third lens group has a fourth lens where at least one refraction surface is aspherical and has minus refractive power. The subminiature optical system can have a high resolution and a compact-sized lens construction with a small number of lens combinations. Also, the subminiature optical system can have a small dimension of an axial direction in a whole construction.

Abstract: A varifocal zoom lens includes: a first lens group having a negative refractive power; a second lens group having a positive refractive power, including a cemented lens component L21 formed by combining a positive lens having a convex surface on the object side and a negative lens having a concave surface on an image side and a positive lens component L22 disposed on the image side with respect to the cemented lens component L21, spaced from the cemented lens component L21 by an air space and having a convex surface on the object side and disposed behind the first lens group with respect to an object side; and a third lens group having a positive refractive power and disposed behind the second lens group with respect to the object side.

Abstract: A photographing lens includes first, second and third lens elements arranged in a sequence from an object side. The first lens element is a positive meniscus with a positive power, and has a convex surface convex to the object side. One of surfaces of the first lens element is aspherical. The second lens element is a positive meniscus with a positive power. The third lens element is a negative meniscus with a negative power, and has a concave surface oriented to the object side. The first, second and third lens elements satisfy conditions of: 0.49<|F2/F3|<1.0, and 0.5<F23/F<4 where F is a lens system composite focal length; F2 is a focal length of the second lens element; F3 is a focal length of the third lens element; and F23 is a composite focal length of the second and third lens elements.

Abstract: Provided is an optical system having an image rotating function disposed on an image side with respect to an image pick up lens, which makes it possible that its optical performance is satisfactory, an eclipse amount is small, a field angle and an F number intended by a photographer are obtained, and compactness is achieved. The optical system is an optical system mountable to the image pick up lens. The optical system includes: an image rotator which is disposed on the image side with respect to a first imaging plane of the image pick up lens and has an incident optical axis and an emission optical axis made coaxial to each other; a first lens unit having a negative optical power which is disposed between the image pick up lens and the first imaging plane; a second lens unit having a positive optical power which is disposed between the first imaging plane and the image rotator; and a third lens unit having a positive optical power which is disposed on the image side with respect to the image rotator.

Abstract: An optical system has a first lens element (L1) having an outer portion (36) and a first tapered surface (34). A second lens element (L2) has an outer portion (26) and a second tapered surface (24). The first lens element (L1) and the second lens element (L2) are spaced apart relative to each other and centered relative to the optical axis (O) by a portion of the first tapered surface (34) being in contact with a portion of the second tapered surface (24), the outer portion (36) of the first lens element (L1) being spaced apart from the outer portion (26) of the second lens element (L2).

Abstract: An image lens array, from object side, comprises a first lens, an aperture, a second lens and a third lens. The first lens is a positive meniscus lens with a convex surface facing the object side; the second lens is positive meniscus lens with a convex surface facing the image side; the third lens is a positive meniscus lens with a convex surface facing the object side; and the first lens, the second lens and the third lens are made of the same plastic material, a focal length of the image lens array is f, a combined focal length of the first and second lenses is f12, a relation between the f and f12 can satisfy the equation: 1.0<f12/f<1.3.

Abstract: A taking lens apparatus has a zoom lens system that is composed of a plurality of lens units and that achieves zooming by varying the distances between the lens units and an image sensor that converts the optical image formed by the zoom lens system into an electrical signal.

Abstract: A zoom lens system in which reductions in the number of lenses and entire lens length are realized is provided. The zoom lens system includes, in order from an object side to an image side, a first lens unit having negative optical power, a second lens unit having positive optical power, and a third lens unit having positive optical power. During zooming from a wide-angle end to a telephoto end, an interval between the first lens unit and the second lens unit reduces and an interval between the second lens unit and the third lens unit changes. An aspherical lens is used for a positive lens element of the first lens unit. Shapes of respective lens elements composing the first lens unit, an interval therebetween, and the like are suitably set.

Abstract: The pickup lens (1) employing the present invention includes a first lens group (11) having negative power, a diaphragm (12), a second lens group (13) having positive power, and a third lens group (14) having negative power, which are arranged in this order from the side of a subject. When varying optical power, in the pickup lens (1), the first lens group (11) is fixed, and the second lens group (13) is moved along the optical axis together with the diaphragm (12), and the third lens group (14) is moved along the optical axis to correct movement of the image point due to variation of optical power.

Abstract: The present invention includes, from an object side to an image-plane side: an aperture stop with a predetermined diameter, a first lens with a positive refractive power having a convex surface on the object side, a second lens with a positive refractive power having a concave surface on the object side, and a third lens with a negative refractive power having a convex surface on the object side. The second and third lenses have aspherical surfaces on their object-side and image-plane-side surfaces. The third lens is formed with an inflection point where the curvature orientation changes within the effective diameter range of the aspherical surface on the image-plane side. An appropriate back focus is maintained while the total length of the lens system is reduced.

Abstract: A projection lens system that projects projected light from a light modulator to a screen, comprising in order from a screen side: a first lens group with a negative refractive power; a second lens group with a positive refractive power; and a third lens group with a positive refractive power is provided. The third lens group includes at least two cemented lenses and a lens with a positive refractive power positioned on an opposite side of the cemented lenses to the screen. Since the projection lens system achieves a sufficiently high correcting performance for various aberrations using fewer aspherical lenses, it is suitable lens system for a rear projector with high image quality.

Abstract: To provide an immersion microscope objective lens capable of making a numerical aperture NA larger than 1.45 even if an ordinary oil is used, the objective lens includes, in order from an object, a first lens group, a second lens group, and a third lens group. The first lens group includes a first cemented lens constructed by a plano-convex lens having a plane surface facing to the object cemented with a meniscus lens having a convex surface facing to an image, and two or more cemented positive lenses disposed to the image side of the first cemented lens. The second lens group includes one or more cemented lens. The third lens group includes, in order from the object, a cemented meniscus lens having a strong concave surface facing to the image, and a cemented meniscus lens having a strong concave surface facing to the object. Given conditional expressions are satisfied.

Abstract: The invention relates to an image-formation optical system that satisfies demands toward high performance and compactness at the same time, and an imaging system incorporating the same. The image-formation optical system comprises, in order from its object side, an aperture stop S, a first positive meniscus lens L1 convex on its object side, a second positive lens L2 having an aspheric surface and a third negative lens L3 having an aspheric surface, and satisfies the following condition. 0.95<?d/f<1.25??(1) Here ?d is the distance on an optical axis of the image-formation optical system from the object side-surface of the first positive meniscus lens to the image plane side-surface of the third negative lens, and f is the focal length of the image-formation optical system.

Abstract: The present invention includes, from the object side to the image plane side, an aperture stop with a predetermined diameter, a first lens with a positive refractive power and a bi-convex shape with convex surfaces facing the object side and the image plane side, a second lens being formed as a meniscus shape with a concave surface facing the object side having a negative refractive power, and a third lens being formed as a meniscus shape with a convex surface facing the object side having a positive refractive power. By having a positive refractive power for the first lens and third lens and a negative refractive power for the second lens, a suitable back focus can be maintained while reducing the total length of the lens system. The imaging lens is thin and compact and has superior optical properties suited for mobile cameras mounted in portable telephones and PDAs.

Abstract: An endoscope objective lens with a three-group, three lens element construction, is formed of, in order from the object side, a first lens element having either a negative meniscus shape or a plano-concave shape with its concave surface on the image side, a stop, a positive second lens element having a plano-convex shape with its convex surface on the image side, and a positive third lens element having a plano-convex shape with its convex surface on the object side. The stop is positioned on or in contact with the object-side surface of the second lens element so that the endoscope objective lens is substantially telecentric. Specified conditions are satisfied in order to reduce aberrations and make the manufacture of the endoscope objective lens easier and less expensive.

Abstract: A projection optical system includes from the enlargement side a first lens unit, a mirror which is an optical path bending member, a second lens unit, and a third lens unit. The projection optical system is designed so that a condition (1), 5.5<T12/FL<12.0, is fulfilled. Here, T12 is the air equivalent distance between the first lens unit and the second lens unit, and FL is the overall focal length of the projection optical system. By fulfilling the condition (1), it is unnecessary that the diameter of the first lens unit be extremely large. It is also unnecessary to change the lens shape to prevent interference between the first lens unit and the second lens units, so that an increase in the cost of the projection optical system can be suppressed.

Abstract: An image forming optical system comprises, in order from an object side, a first positive meniscus lens having a convex surface directed toward an object side, an aperture stop, a second positive meniscus lens having a convex surface directed toward the object side and a negative lens. At least one of surfaces of the negative lens is a spherical and the following condition is satisfied: ?2.0<?m/?p<0 ?2.0<(r1r+r2f)/(r1r?r2f)<1.0 where ?m represents the power of the negative lens at the position of the maximum light height and ?p represents the power of the negative lens at the position of the near axis, r1r represents the radius of curvature of the first lens at the image side and r2f is the radius of curvature of the second lens at the object side.

Abstract: A single-focus lens for an electronic still camera is formed of at least one meniscus lens element that is placed on the object side of a stop, with at least one surface of this meniscus lens element having a curvature such that light rays that pass through the stop are incident the surface substantially normally for all field angles, and an infrared-blocking coating is provided on the surface. Preferably, two specified conditions are satisfied to ensure that rays which are incident onto the coating are not adversely affected by the coating, thereby preventing color variations of objects which otherwise would occur.

Abstract: A zoom lens system, includes a first lens unit, a second lens unit, and a third lens unit. The second lens unit is moved to the object side in zooming such that an interval between the first lens unit and the second lens unit at a telephoto end becomes smaller than an interval between the first lens unit and the second lens unit at a wide angle end. The first lens unit includes a first lens element, a second lens element, and a third lens element. The first lens element has an aspherical surface of a shape that the negative refracting power decreases from a lens central portion to a lens peripheral portion. The second lens element is formed in a meniscus shape which is convex on the object side. A refractive index of a material constituting the first and second lens elements is appropriately selected.

Abstract: The present invention is an imaging lens in which various aberrations are favorably corrected, the optical length is short, and a sufficient back focus is secured. The imaging lens is constituted by arranging a first lens L1, an aperture diaphragm S1, a second lens L2, and a third lens L3 in succession from the object side to the image side. The first lens L1 is a lens having a positive refractive power and a meniscus shape in which the convex surface faces the object side, the second lens L2 is a lens having a negative refractive power and a meniscus shape in which the convex surface faces the image side, and the third lens L3 is a lens in which the convex surface faces the object side.

Abstract: A zoom lens system for forming an optical image of a subject on the image-sensing surface of an image sensor has three lens units, namely, from the object side thereof, a first lens unit having a negative optical power, a second lens unit having a positive optical power, and a third lens unit having a positive optical power, and achieves zooming by varying the distances between the individual lens units in such a way that, during zooming from the wide-angle end to the telephoto end, the distance between the first and second lens units decreases. The first lens unit is composed of two or more lens elements, and the first lens element, i.e., the lens element disposed at the object-side end of the first lens unit, is a plastic lens element. Moreover, a prescribed conditional formula is fulfilled.

Abstract: A zoom lens includes three lens groups. The first lens group from the object side has negative refractive power and is formed of a lens component having negative refractive power and a lens element having positive refractive power. The second lens group from the object side has positive refractive power and is formed of two lens components, an object-side lens component that is a glass lens element with a convex surface on the optical axis on the object side and having an aspheric surface and an image-side lens component that includes a cemented surface and an image-side concave surface. The third lens group consists of a biconvex lens component. Only the first and second lens groups move along the optical axis for zooming. The zoom lens may be formed of only six lens elements, includes at least one aspheric surface, and satisfies specified conditions for compactness and aberration correction.

Abstract: A single focus lens includes, in order from the object side: a first lens component of positive refractive power with a convex surface on the object side; a diaphragm stop; a second lens component that is made of plastic, has at least one aspheric surface and a meniscus shape, and has a concave surface on the object side near the optical axis; and, a third lens component of positive refractive power with two aspheric surfaces, one of which is convex on the object side near the optical axis. Each lens component that forms the single focus lens may consist of a lens element. Specified conditions are satisfied in order to reduce aberrations, to insure that the light rays at the image plane are substantially orthogonal to the image plane, and to insure that a sufficient back focus is provided to allow for insertion of other optical elements.

Abstract: Refractive optical systems having first and second lens systems are transmissive to infrared radiation. The first lens system includes one of BaF2 and CaF2. An exemplary second lens system includes an optical material selected from at least spinel, MgF2, and aluminum oxynitride. Such exemplary refractive optical systems provide correction of chromatic aberration in multiple wavelength bands.

Abstract: A compact zoom lens system allowing excellent image quality regardless of an object distance, is disclosed. The disclosed zoom lens system comprises, in order from an object side to an image side, a first, a second, and a third lens units having a positive, a positive, and a negative optical powers, respectively. The spacings between the first and second lens units and between the second and third lens units are changed during zooming. The second lens unit is constituted by, in order from the object to image side, a first lens subunit having a positive or negative optical power and a second lens subunit having a positive optical power. At least the second lens subunit is moved toward the object side to change the spacing between the first and second lens subunits during focusing on an object at a short distance from an object at infinity at least one zoom position.

Abstract: A single focus lens includes, in order from the object side: a glass first lens component of positive refractive power and with a convex surface on the object side; a diaphragm stop; a second lens component of plastic, a meniscus shape with its concave surface on the object side, and which includes at least one aspheric surface; and a third lens component of plastic, a meniscus shape with it convex surface on the object side, and which includes two aspheric surfaces. Each lens component may consist of a single lens element. Specified conditions are satisfied in order to reduce aberrations, to insure that the light rays at the image plane are substantially orthogonal to the image plane, and to insure that a sufficient back focus is provided so as to enable the insertion of other optical elements.

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: The subject invention relates to broadband optical metrology tools for performing measurements of patterned thin films on semiconductor integrated circuits. Particularly a family of optical designs for broadband, multi-wavelength, DUV-IR (185<?<900 nm) all-refractive optical systems. The designs have net focusing power and this is achieved by combining at least one positively powered optical element with one negatively powered optical element. The designs have small spot-size over the wavelength range spanning 185-900 nm with substantially reduced spherical aberration, axial color, sphero-chromatism and zonal spherical aberration. The refractive optical systems are broadly applicable to a large class of broadband optical wafer metrology tools including spectrophotometers, spectroscopic reflectometers, spectroscopic ellipsometers and spectroscopic scatterometers.

Abstract: Optical devices achromatize the output from a highly efficient refractive laser beam reshaper, thereby allowing collimated, diffraction limited flat-top laser beams to be generated over a wide spectral interval, e.g., over 200 nm in the visible. While the beam reshaper may utilize refractive aspheric lenses, the achromatizers use cost effective spherical refractive elements.

Abstract: A wide angle lens system comprises at least three lens element cemented together as a single lens unit and an object side part of the lens unit has a negative refractive power and a rear part of the lens unit has a positive refractive power.

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: Disclosed is a lens system installed in a mobile communication terminal, comprising: a first lens including at least one aspherical plane and having a positive refractivity; a perforated iris separated from the first lens by a designated distance for preventing unnecessary incident light from being incident onto an optical system; a second lens separated from the perforated iris by a designated distance, including at least one aspherical plane and having a positive refractivity; and a third lens separated from the second lens by a designated distance, including at least one aspherical plane and having a negative refractivity, wherein the first lens, the perforated iris, the second lens and the third lens are arranged sequentially from a subject, and the perforated iris is located between the first lens and the second lens.

Abstract: An image forming optical system comprises, in order from an object side, a first positive meniscus lens having a convex surface directed toward an object side, an aperture stop, a second positive meniscus lens having a convex surface directed toward the object side and a negative lens.

Abstract: A projection lens of the retrofocus type which has a long back focus, can project with a high contrast, exhibits small aberrations such as a distortion aberration and converts a light path in the inside thereof. A first lens set (0) having a negative refractive power and having light path conversion means built therein, an iris (400) and a second lens set (300) having a positive refractive power and including an aspheric lens are disposed in order from the screen side. The first lens set (0) includes a first A lens set (100) having a negative refractive power and including one or more aspheric lenses, a bending mirror (M) serving as the light path conversion means, and a first B lens set (200) having a positive refractive power. The lenses in the first A lens set have an outer shape with a portion thereof cut outside an effective light ray in a direction of the light path conversion, and the direction of the light path conversion is a direction of a shorter side of the rectangular image formation element.

Abstract: The present invention is directed to a projection lens that has a sufficiently long back focus to enable a wide-angle projection and has astigmatism, abaxial spherical aberration (coma), distortion, and other types of aberration satisfactorily corrected. The projection lens includes first to third groups of lenses G1, G2 and G3. The first group of lenses G1 consist of four pieces of lenses, and the first or foremost negative one of the lenses is an aspheric lens. The second group of lenses G2 consist of two pieces of lenses, and the first or foremost negative one and the second positive one of the lenses are joined together. The third group of lenses G3 consist of six pieces of lenses, and the second foremost positive one, the third negative one, and the fourth positive one of the lenses are joined together. The projection lens is characterized in that the following formulae are satisfied; bf/f≧2.8   (1) 1.1≦f2/f3≦1.6 , and   (2) 1.65≦|f1|/f≦2.

Abstract: This invention provides a zoom lens system with, in succession from the front to rear, a first lens unit of negative optical power, a second lens unit of positive optical power and a third lens unit of positive optical power. When zooming from a short focal length end to a long focal length end, the second lens unit moves forward, while the third lens unit moves along a locus that is located rearmostly at other zoom position than the short focal length end and that is convex toward the image side or a part of it. The first lens unit does not move. Further, the first lens unit has a negative lens with a concave rear surface, and a positive lens with a convex front surface. The second lens unit has a negative lens with a concave rear surface, and a positive lens disposed rearwardly of the negative lens.

Abstract: The present invention provides a compact, thin zoom lens. The zoom lens according to the present invention includes, from an object side to an image plane side, a first lens group having an overall negative overall refractive power, a second lens group having an overall positive refractive power; and a third lens group having an overall positive refractive power. The first lens group includes a first lens and a second lens bonded together and having a negative refractive power. The second lens group includes a third lens with a positive refractive power, and a fourth lens and a fifth lens bonded together and having a negative refractive power. The third lens group includes a sixth lens having a positive refractive power. As a result, the total length is reduced, the retracted length can be reduced, and the zoom lens can be compact and thin.

Abstract: A single focus lens is disclosed that is formed of only three lens components. In order from the object side, these are: a first lens component that has positive refractive power and includes a first lens element; an aperture diaphragm; a second lens component that has positive refractive power, at least one aspheric lens surface, and includes a second lens element made of plastic; and a third lens component that has positive refractive power, at least one aspheric lens surface, and includes a third lens element made of plastic. The following condition is satisfied: 1.0<f1/f<5.0 where f1 is the focal length of the first lens component, and f is the focal length of the single focus lens.

Abstract: A single focus lens includes, in order from the object side: a first lens component of positive refractive power with a convex surface on the object side; a diaphragm stop; a second lens component that is made of plastic, has at least one aspheric surface and a meniscus shape, and has a concave surface on the object side near the optical axis; and, a third lens component of positive refractive power with two aspheric surfaces, one of which is convex on the object side near the optical axis. Each lens component that forms the single focus lens may consist of a lens element. Specified conditions are satisfied in order to reduce aberrations, to insure that the light rays at the image plane are substantially orthogonal to the image plane, and to insure that a sufficient back focus is provided to allow for insertion of other optical elements.

Abstract: An objective lens device and an optical pickup employing the objective lens device. The objective lens device is formed of three lenses including a lens having a negative power and formed of material having an Abbe number which is 45 or less in line d. At least one surface of surfaces of the three lenses is formed to be aspherical. Thus, in the objective lens device, a high numerical aperture of 0.70 or more is realized and chromatic aberration is corrected with respect to blue light enabling improved recording and/or reproduction using blue light.

Abstract: A zoom lens system comprises a first lens group having negative refractive power, a second lens group having positive refractive power, and a third lens group having positive refractive power. The first lens group includes a first lens unit having negative refractive power, which includes a negative lens and a negative lens having at least one aspherical surface, and a second lens unit including a positive lens. The second lens group includes an aperture element, a first lens unit having positive refractive power, which has a positive lens, a second lens unit having positive refractive power, which has a cemented positive lens including a positive lens and a negative lens, and a third lens unit having negative refractive power, which has a negative lens having at least one aspherical surface. The third lens group includes a positive lens plating with a multi-layer coating in the surface facing to the object side in order to cut off infrared rays and decrease the influence of infrared rays on image.

Abstract: An endoscope objective lens with a three-group, three lens element construction, is formed of, in order from the object side, a first lens element having either a negative meniscus shape or a plano-concave shape with its concave surface on the image side, a stop, a positive second lens element having a plano-convex shape with its convex surface on the image side, and a positive third lens element having a plano-convex shape with its convex surface on the object side. The stop is positioned on or in contact with the object-side surface of the second lens element so that the endoscope objective lens is substantially telecentric. Specified conditions are satisfied in order to reduce aberrations and make the manufacture of the endoscope objective lens easier and less expensive.

Abstract: A compact optical system includes a reduced number of lens elements with a bendable optical path and so is compatible with miniature image pickup devices. The image pickup lens includes, in order from its object side, a first lens element having a negative refracting power, a second lens element having positive refracting power, a stop, a third lens element having a negative refractive power and a fourth lens element having positive refracting power, and satisfies the following conditions (1) and (2) 50>&ngr;d1−&ngr;d2>10  (1) 2>f/f3>0.35  (2) where &ngr;d1 is the d-line reference Abbe number of the first lens element, &ngr;d2 is the d-line reference Abbe number of the second lens element, f is the focal length of the image pickup lens, and f3 is the composite focal length of the third and fourth lens elements. Between the first and the second lens element there is interposed a reflecting surface.

Abstract: An optical scanner according to the present invention comprises a first imaging optical system consisting of a collimator lens and a cylindrical lens, a light deflector reflecting/deflecting a light beam for scanning, and a second imaging optical system consisting of an f-&thgr; lens and an anamorphic lens. The f-&thgr; lens has three groups of lenses, i.e., a first lens having negative refracting power, a second lens having positive refracting power and a third lens having positive refracting power. The f-&thgr; lens is formed to satisfy relational expressions L/f<0.100 and 0.10≦r1/r3≦0.26, where L represents the total length of the f-&thgr; lens, f represents the focal distance of the f-&thgr; lens, r1 represents the radius of curvature of a light beam entrance-side refracting interface of the first lens and r3 represents the radius of curvature of a light beam entrance-side refracting interface of the second lens.

Abstract: A zoom lens with a slim and compact design has arranged in sequence from the object side to the image plane side a first lens group having a negative refractive power, a second lens group having a positive refractive power, and a third lens group having a positive refractive power. The first lens group is formed from a first lens having a negative refractive power and a second lens having a positive refractive power. The second lens group is formed from a third lens having a positive refractive power and a fourth lens and a fifth lens. The fourth and fifth lens are joined together and have a negative refractive power. The third lens group is formed from a sixth lens having a positive refractive power. The zoom lens has a short length when retracted and extended, and a design that is compact and thin.

Abstract: Provided are an optical correcting system which can form a linear image or illuminating light having a substantially uniform light intensity distribution without reducing the efficiency of use of light, and an exposure head which can perform excellent exposure by using the linear image or the illuminating light. Light flux from a light source is collimated by the function of a collimator lens, and the collimated light flux enters into an optical correcting system for correcting light intensity distribution. The optical correcting system for correcting light intensity distribution changes the width of the light flux at the exit position at which each collimated light flux exits so that the light intensity distribution of a linear image is uniform when the collimated light flux is formed into the linear image.

Abstract: A lens assembly includes an aperture and a lens unit. The lens unit includes a first lens, a second lens, and a third lens in sequence from an object side toward an image side. The first lens is a positive lens having a concave surface that faces the image side. The second lens is a meniscus lens having a concave surface that faces the first lens and a convex surface that faces the third lens. The third lens is a non-spherical lens having two wavelike surfaces in the formation of concavity-convexity-concavity or convexity-concavity-convexity and being symmetrically formed with respect to an optical axis. The aperture is disposed behind the first lens. A coverage angle of the lens unit is ranged between 60° and 70°. Accordingly, the arrangement of the lens assembly greatly reduces the optical distortion to improve the image quality.

Abstract: Catadioptric projection systems are disclosed for projecting an illuminated region of a reticle onto a corresponding region on a substrate. The systems are preferably used with ultraviolet light sources (e.g., 193 nm). The systems comprise a first imaging system, a concave mirror, and a second imaging system. The first imaging system comprises a single-pass lens group and a double-pass lens group. The single-pass lens group comprises a first negative subgroup, a positive subgroup, and a second negative subgroup. Light from the illuminated region of the reticle passes through the single-pass lens group and the double-pass lens group, and reflects from the concave mirror to pass back through the double-pass lens group to form an intermediate image of the illuminated region of the reticle. The light is then directed to the second imaging system that re-images the illuminated region of the reticle on the substrate.