Abstract: Alignment accuracy between two or more patterned layers is measured using a metrology target comprising substantially overlapping diffraction gratings formed in a test area of the layers being tested. An optical instrument illuminates all or part of the target area and measures the optical response. The instrument can measure transmission, reflectance, and/or ellipsometric parameters as a function of wavelength, polar angle of incidence, azimuthal angle of incidence, and/or polarization of the illumination and detected light. Overlay error or offset between those layers containing the test gratings is determined by a processor programmed to calculate an optical response for a set of parameters that include overlay error, using a model that accounts for diffraction by the gratings and interaction of the gratings with each others' diffracted field. The model parameters might also take account of manufactured asymmetries.

Abstract: A multi-stage microlens array with an array of compound lenses, each compound lens having a sequence of progressively smaller, higher-power lens elements. The array can have a high fill factor over the first-stage lens array, but still provide sufficient space between the terminal lens elements to accommodate structural support and components such as lens focus actuators. The microlens array can be incorporated into a printing system that includes an optical projection system, a scanning mechanism, an array of light-modulating image source elements providing an image source, and an image modulation mechanism that controls the image source as the printing surface is scanned. The microlens array can also be incorporated into an imaging system that includes an optical projection system, a scanning mechanism, an array of light-sensing detector elements, and a data acquisition system that records the detector response as the scanning mechanism operates.

Abstract: A database interpolation method is used to rapidly calculate a predicted optical response characteristic of a diffractive microstructure as part of a real-time optical measurement process. The interpolated optical response is a continuous and (in a preferred embodiment) smooth function of measurement parameters, and it matches the theoretically-calculated optical response at the database-stored interpolation points.

Abstract: The present invention relates to a shear blade assembly for a shearing system. The shear blade assembly includes an upper shear blade and a lower shear blade. The top surface of the lower shear blade is inclined downwardly at an angle of between 0.2 and 0.5 degrees to the horizontal. The bottom surface of the upper shear blade is raked relative to the horizontal, longitudinally of the blades.

Abstract: A small-spot imaging, spectrometry instrument for measuring properties of a sample has a polarization-scrambling element, such as a Lyot depolarizer, incorporated between the polarization-introducing components of the system, such as the beamsplitter, and the microscope objective of the system. The Lyot depolarizer varies polarization with wavelength. Sinusoidal perturbation in the resulting measured spectrum can be removed by data processing techniques or, if the depolarizer is thick or highly birefringent, may be narrower than the wavelength resolution of the instrument.

Abstract: A method of measuring at least one parameter associated with a portion of a sample having formed thereon one or more structures with at least two zones each having an associated zone reflectance property. The method includes the steps of illuminating the zones with broadband light, and measuring at least one reflectance property of light reflected from the at least two zones. The measurement includes a substantial portion of non-specularly scattered light, thereby increasing the quality of the measurement. The method further includes the step of fitting a parameterized model to the measured reflectance property. The parameterized model mixes the zone reflectance properties of the zones to account for partially coherent light interactions between the two zones.

Abstract: The present invention relates to a shear blade assembly for a shearing system. The shear blade assembly includes an upper shear blade and a lower shear blade. The top surface of the lower shear blade is inclined downwardly at an angle of between 0.2 and 0.5 degrees to the horizontal. The bottom surface of the upper shear blade is raked relative to the horizontal, longitudinally of the blades.

Abstract: A microscopy and/or lithography system uses a comparatively low-resolution image projection system, which has a very small numerical aperture but large image field, in conjunction with a microlens array comprising miniature lens elements, each of which has a large numerical aperture but very small field. The projection system contains a small aperture stop which is imaged by the microlenses onto an array of diffraction-limited microspots on the microscope sample or printing surface at the microlens focal point positions, and the surface is scanned to build up a complete raster image from the focal point array. The system design thus circumvents the tradeoff between image resolution and field size which is the source of much of the complexity and expense of conventional wide-field, high-NA microscopy and microlithography systems.

Abstract: The present invention relates to a shearing system. The shearing system includes a die assembly having linear bearings and guide rails for guiding movement of the upper die shoe. Gas springs return the die shoe to the open position.

Abstract: A microscopy and/or lithography system uses a comparatively low-resolution image projection system, which has a very small numerical aperture but large image field, in conjunction with a microlens array comprising miniature lens elements, each of which has a large numerical aperture but very small field. The projection system contains a small aperture stop which is imaged by the microlenses onto an array of diffraction-limited microspots on the microscope sample or printing surface at the microlens focal point positions, and the surface is scanned to build up a complete raster image from the focal point array. The system design thus circumvents the tradeoff between image resolution and field size which is the source of much of the complexity and expense of conventional wide-field, high-NA microscopy and microlithography systems.

Abstract: A system for bringing the joint edges of first and second sheet metal components into butting relationship. The components are clamped in opposing clamping assemblies with one of the assemblies being movable toward and away from the other. A fluid motor is mounted on one clamping assembly and a piston extending therefrom is connected to the other clamping assembly through a pair of expandable bladders. By sequentially introducing high and low pressure air to first one bladder and then the other, the movable clamping assembly is caused to move one component toward the other while accommodating any initial misalignment between the edges.

Abstract: A system and method for laser welding. The joint edges of two adjacent sheet metal components are brought into butting relationship on a weld line. A welding head is moved along the weld line while directing a laser welding beam downwardly from its optics to the weld line where it creates a weld joint. In its path downwardly to a focal point at the weld line the beam passes through a stream of air directed transversely of the beam, a shield plate below the stream of air and above the weld line, and a nitrogen filled zone below the shield and above the weld joint.

Abstract: A system for clamping a sheet metal component in preparation for welding or the like. A clamping assembly includes a horizontally elongated lower clamping platen and a horizontally elongated upper clamping platen positioned over said lower platen. The upper platen includes an elongated carrier and a series of clamping pads, separately mounted on the carrier for movement toward and away from the carrier. A pair of coil springs between each pad and the carrier bias the pad away from the carrier. The pads are mounted for progressively further movement away from the carrier as they are displaced further from the centerline of the carrier.

Abstract: A system for gauging the relative positions of two opposing joint edges on sheet metal components prior to welding. The system comprises a gauging assembly including two pairs of gauging pins which are movable between a retracted position and a gauging position. Each pair of pins defines a separate edge contact line. When each joint edge has contacted both pins in a respective pair, electrical circuitry indicates as much and the components are clamped in this relationship.

Abstract: The present invention relates to shearing apparatus, and method of operating the same. The apparatus may include a plurality of spring clamping members positioned longitudinally along a first die shoe, the clamping members positioned in raised stepped sequence from a centerline perpendicular to longitudinal sides of the die shoe to sequentially contact with the sheet material. The shearing apparatus may include a die assembly having linear bearings and guide rails for guiding movement of the die shoe, and gas springs which return the die shoe to the open position. The shearing apparatus provides straight cuts with a maximum cut-edge tolerance of 0.0015 inch. The shearing apparatus may include a second die shoe having an angled blade to allow a higher shear to break ratio.

Abstract: Because of diffraction effects caused by slits or apertures in optical measurement systems, the radiation energy which is directed towards a particular region on a sample will be spread over a larger area than desirable. By employing an apodizing filter in the radiation path in such system, diffraction tails of the system will be reduced. The apodizing filter preferably has a pattern of alternating high transmittance areas and substantially opaque areas where the locally averaged transmittance function is an apodizing function. In the preferred embodiment, the locally averaged transmittance function varies smoothly and monotonically from the periphery to the center of the filter.

Abstract: The present invention relates to a system for welding a joint edge of a first sheet metal component to a joint edge of a second sheet metal component to form a weld joint. The system includes a gauging sub-system which positions each joint edge at a desired distance from a weld line. A sub-system then clamps the sheet metal components in this relationship. A joint edge butting sub-system then moves the clamped components toward each other until the edges are in butting relationship. A laser welding sub-system then moves a welding head along the butted edges to form the weld joint. The laser beam, which forms the weld joint, passes through an air shield in the welding mechanism so that weld splatter from the welding zone is carried off by an air stream and does not reach the welding head optics. The invention also relates to a method of laser welding.

Abstract: This invention is a novel solar tracking mechanism incorporating a number of practical features that give it superior environmental resilience and exceptional tracking accuracy. The mechanism comprises a lightweight space-frame assembly supporting an array of point-focus Fresnel lenses in a two-axis tracking structure. The system is enclosed under a glass cover which isolates it from environmental exposure and enhances tracking accuracy by eliminating wind loading. Tracking accuracy is also enhanced by the system's broad-based tracking support. The system's primary intended application would be to focus highly concentrated sunlight into optical fibers for transmission to core building illumination zones, and the system may also have potential for photovoltaic or photothermal solar energy conversion.

Abstract: A transmission grating is used to reduce chromatic aberration in a Fresnel lens, wherein the lens chromatic dispersion is offset and substantially canceled by the grating's diffraction-induced dispersion. The grating comprises a Fresnel-type pattern of microscopic facets molded directly into the lens surface. The facets would typically have a profile height of around 4.multidot.10.sup.-5 inch and a profile width of at least 10.sup.-3 inch. In its primary intended application, the invention would function to improve the optical performance of a Fresnel lens used to concentrate direct sunlight.

Abstract: This invention is a novel solar tracking mechanism incorporating a number of practical features that give it superior environmental resilience and exceptional tracking accuracy. The mechanism comprises a lightweight space-frame assembly supporting an array of point-focus Fresnel lenses in a two-axis tracking structure. The system is enclosed under a glass cover which isolates it from environmental exposure and enhances tracking accuracy by eliminating wind loading. Tracking accuracy is also enhanced by the system's broad-based tracking support. The system's primary intended application would be to focus highly concentrated sunlight into optical fibers for transmission to core building illumination zones, and the system may also have potential for photovoltaic or photothermal solar energy conversion.