Importance

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Abstract

Exit pupil and source telecentricity of a projection imaging tool system is determined. The system contains a light source, an optical imager, a reticle, a substrate, and a positioner. The light source is optically coupled to the optical imager, the optical imager having an exit pupil. The combination of the light source and the optical imager define a projection imaging tool, are characterized by a partial coherence. The reticle has an array of patterns, each pattern having at least a first feature and a second feature. A substrate may be used to record at least a first image and a second image of the features. The positioner is used to dispose the first image and the second image such that the first image has a first defocus and the second image has a second defocus different from the first defocus. A processor is used to calculate the telecentricity based on an exit pupil and light source differential shift coefficient and positional offsets between features contained in the first image and features contained in the second image.

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First Claim