Abstract: A zoom lens system includes a positive first lens group, a positive second lens group, and a negative third lens group. Zooming is performed by moving the first, second and third lens groups in the optical axis direction. The positive first lens group is constituted by a negative lens element and a positive lens element. The zoom lens system satisfies the following condition: 0.15<&Sgr;d2G/fW<0.28  (1) wherein &Sgr;d2G designates the distance from the most object-side surface of the positive second lens group to the most image-side surface thereof; and fW designates the focal length of the entire zoom lens system at the short focal length extremity.

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: An autofocus system for an imaging device that includes an image detecting element for image production at a focused image plane of an adjustable focus imaging lens that also includes four image detecting elements for focus detection arranged in pairs that are equidistant in front of, and behind, planes that are conjugate with the focused image plane. One pair of image detecting elements for focus detection are farther than the other pair from the conjugate planes and may be used alone for focusing based on the stop value or focal length of the adjustable focus imaging lens. Alternatively, the other pair of image detecting elements may be used for more accurate focusing after the one pair of image detecting elements is used. The use of two pairs of image detecting elements at different distances from the focused image plane provides accurate focusing over a wide range of object distances.

Abstract: Apparatus and methods for reducing optical distortion in an optical system by thermal means are disclosed. The apparatus includes a heating/cooling system spaced apart from and in thermal communication with an internally reflecting surface of a refractive element in the optical system. The heating/cooling system is adapted to create a select temperature distribution in the refractive optical element near the internally reflecting surface to alter the refractive index and/or the surface profile in a manner that reduces residual distortion.

Abstract: An optical lens including an optically clear lens element; and a light absorbing coating on a surface of the lens that attenuates transmitted light; has a coloured or colourless reflection as seen from the front of the sunglass lens; and is anti-reflective as seen from the eye side of the lens.

Abstract: A zoom lens system includes a positive first lens group and a negative second lens group which move in an optical axis direction upon zooming. The positive first lens group includes a positive first lens element having a convex surface on the object side, a negative second lens element, and a positive third lens element. The negative second lens group includes a positive meniscus lens fourth lens element having the concave surface facing toward the object, and a negative meniscus fifth lens element having the concave surface facing toward the object. The following conditions (1), (2) and (3) are satisfied: 1.2<ft/f1<1.8  (1); 3.8<ft/f1G<4.2  (2); and  1≦SF1<6; wherein ft designates the entire focal length at the long focal length extremity; f1 designates the focal length of the positive first lens element; f1G designates the focal length of the positive first lens group, and SF1 designates the shape factor of the positive first lens element.

Abstract: A zoom lens system has, in order from an enlargement side, a first lens unit having negative optical power, a second lens unit having positive optical power, a third lens unit having positive optical power, a fourth lens unit having negative optical power, including an aperture stop, a fifth lens unit having positive or negative optical power, and a sixth lens unit having positive optical power. Zooming is achieved by varying the first to fifth variable distances between the lens units. The third and fifth lens units move from the enlargement side to the reduction side during zooming from the telephoto end to the wide-angle end. The zoom lens system is substantially telecentric toward the reduction side.

Abstract: A three-unit zoom lens includes, in order from the object side, the first lens unit with positive refracting power, the second lens unit with positive refracting power, and the third lens unit with negative refracting power. When the magnification of the zoom lens is changed, extending from the wide-angle position to the telephoto position, individual lens units of the three-unit zoom lens are moved toward the object side so that a space between the first lens unit and the second lens unit, after being increased as the lens units are moved from the wide-angle position toward the proximity of the middle position, is decreased as they are moved toward the telephoto position, and a space between the second lens unit and the third lens unit is also decreased accordingly. In this case, the three-unit zoom lens has a variable magnification ratio of 2 or higher and the first lens unit is constructed with a single lens element.

Abstract: A system and method for designing a progressive lens. Mean power is specified at points distributed over the entire surface of the lens and lens height is specified around the edge of the lens. Lens height is determined at the points consistent with the specified mean power and the lens edge height in part by solving a partial differential equation of the elliptic type subject to the lens edge height as a boundary condition. A successive over-relaxation technique may be employed to converge on the solution to the partial differential equation, and an over-relaxation factor may be determined to most efficiently relax the equation.

Abstract: The disclosed zoom lens includes 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 in order from an object side to an image side. The zoom lens has a shorter interval between the first lens unit and the second lens unit and a longer interval between the second lens unit and the third lens unit on a telephoto end than an interval between the first lens unit and the second lens unit and an interval between the second lens unit and the third lens unit on a wide angle end, respectively.

Abstract: A five-group zoom lens is formed of, in order from the enlarging side of the zoom lens, a negative first lens group that is movable for focusing and that is stationary during zooming, a positive second lens group, a positive third lens group, a negative fourth lens group, and a positive fifth lens group that is stationary during zooming. The second lens group, the third lens group, and the fourth lens group move relative to one another and relative to the first and fifth lens groups during zooming. The second lens group includes a negative lens component that has a concave lens surface on the reducing side of the zoom lens. The zoom lens satisfies various conditions and may be used in a projection display device or an image pickup device such as a camera.

Abstract: A telephoto lens for a grating scale measurement system includes a pair of aspheric lenses that together operate at finite conjugates with minimal spherical aberrations. Identical aspheric lenses provide a subsystem with a magnification of 1×, and a magnifying system typically including one or more negative lens increases the magnification of an intensity pattern to enable accurate measurement of the phase of the intensity pattern.

Abstract: A single focus lens is disclosed that is formed of only four lens components, which are arranged in positive, negative, positive and relatively weak positive or negative refractive power order from the object side, with a stop arranged between the first and second lens components. The third lens component has a convex surface on its image side, and the fourth lens component has a meniscus shape, is made of plastic, includes at least one aspheric surface, and is concave on its image side. The second lens component is formed of a single lens element, and various conditions are preferably satisfied so as to provide a compact lens having a short overall length while favorably correcting various aberrations.

Abstract: A method for detecting the maximum quantity of possible positions of an exchangeable nosepiece or slide in a microscope system is disclosed. The method comprises the steps of: starting from an initial position which corresponds to a first position, adjusting the maximum position; comparing the maximum position to a position registered in a memory; and storing the results of the comparison.

Abstract: A lens system includes a plastic positive lens, a plastic negative lens and a glass positive lens. The plastic lenses are made to be meniscus lenses and an aspheric surface and a diffractive surface are respectively mounted onto the plastic lenses so as to have better image with low manufacturing cost.

Abstract: A single element objective lens for an optical disc drive converges a laser beam, which is emitted by a laser source, on a data recording surface of an optical disc through a protective layer of the optical disc. One surface of the objective lens is divided into a central area including an optical axis thereof and a peripheral area surrounding the central area. The peripheral area is provided with a diffraction lens structure formed by a plurality of concentric annular zones including minute steps. The central area is a continuous surface having no stepped portions. The diffraction lens structure compensates for variation of converging characteristic of the objective lens due to a change of a temperature.

Abstract: The present invention provides a zoom lens suitable for an image pickup system using a solid-state image pickup element. In detail, the zoom lens disclosed in the present invention includes three lens units having negative, positive, and positive optical power in order from an object side to an image side, in which zooming is performed by moving each lens unit in the direction of an optical axis. The first lens unit has at least one positive lens and at least one negative lens. The second lens unit has at least one positive lens and at least one negative lens, in which a plastic lens of positive optical power is disposed on the side closest to the object.

Abstract: An integrated light-transmission optical module for a safetyoptoelectronic barrier, comprises a condenser element having a first lens, and an objective having a second lens which are located respectively at a first end and a second end. The module comprises a single-piece entity made of transparent material, and having an intermediate zone provided with deflectors formed by a succession of dioptric surfaces distributed along the direction of light flux propagation between the first lens and the second lens. The deflectors ensure a deflection outside the optical module of stray rays reflected inside the module, so as to prevent transmission of strays rays, either through the second lens of the objective if it is a light transmission coming from the condenser element, or through the first lens when receiving light coming from the second lens.

Abstract: A catadioptric projection lens configured for imaging a pattern arranged in an object plane (2) onto an image plane (4) while creating a single, real, intermediate image (3) has a catadioptric first section (5) having a concave mirror (6) and a beam-deflection device (7), and a dioptric second section (8) that commences after the beam-deflection device. The system is configured such that the intermediate image follows the first lens (17) of the dioptric section (8) and is preferably readily accessible. Arranging the intermediate image both between a pair of lenses (17, 21) of the dioptric section and at a large distance behind the final reflective surface of the beam-deflection device helps to avoid imaging aberrations.

Abstract: An optical system includes a first cylindrical optical element (lens or mirror), and a second cylindrical optical element positioned in a round-spot plane following the first cylindrical optical element. At least one of the cylindrical optical elements is rotatable about the optical axis, relative to the other cylindrical optical element. A collimated light beam is incident on the first cylindrical optical element. Rotating the cylindrical optical elements relative to each other allows changing the size of a round spot or scaling an image at a given output location. In one implementation, two positive-magnification cylindrical lenses of focal length f are separated by a distance 2f. Rotating one of the lenses about the optical axis changes the diameter of a round spot (or symmetrically scales an image) at a fixed position away from the second lens.