Importance

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Abstract

An electro-optical gauging system for measuring the flatness of an edge of a workpiece which may be closed upon itself and of non-circular form by mounting the piece centered on a flat circular table having radial slots and an open center. A line source of light of uniform intensity is located at the table center to project a line image along a slot as the table is rotated around an axis of rotation perpendicular to its plane and coincident with the line image. The distance along the slot depth dimension from a reference edge in each slot to the workpiece edge is measured by measuring the width of the light beam passed between the reference edge and the workpiece edge. Measurements are made by passing collimated light between the edges to be measured. The light is imaged by a quasi-telecentric system onto a linescan camera having a linear array of pixels extending along the image length. Image-to-camera distance variations are accommodated by the imaging lens system. The effect of the blurring at the ends of the line image is eliminated by electrical signal compensation. A sampling linescan establishes the maximum light intensity level along the length of the line image. A measurement scan measures the line image length as a pixel count for those pixels having an incident light intensity equal to or greater than one-half the maximum level initially sampled.

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First Claim