Rca Inc.

Robert L Covey

Michael T Gale

Istvan Gorog

John Prickett Beltz

A method and apparatus for determining the true edge length of a body subtended by two other body edges comprises exposing the body to a beam of light such that the edge is imaged by an optical system for projecting a linear section across the body as a silhouette-like image onto a linear array of photosensitive detectors. The image is usually blurred due to diffraction effects. The body is initially positioned in focus and then scanned moving the array provide an image of at least a portion of the desired edge to define a reference line representing the location of the edge. The array is then moved in scanned sequence from that reference line to provide fifty percent (50%) intensity level data points to define the other body edges. Lines are fitted through such data points and extended to intersect the reference line to determine the true length of the edge even with a blurred image of portions of that edge.

Method and apparatus of determining the true edge length of a body

A system for positioning a body having two opposed edges and having a first axis oriented to pass through the two edges. A beam of light oriented along a second axis orthogonal to the first axis images one or both of the edges onto all or a portion of a photodetector array which is aligned in a direction parallel to the first axis. The array is scanned to obtain a light intensity transition profile of all or part of the projected image whereby the profile has either one or two 50% intensity points. The body is then shifted until both of the 50% intensity points strike predetermined locations on the array indicating that both the edges are included in the image. The body is shifted along the first axis until the fifty percent (50%) intensity point along the transition profile strikes a predetermined location along the photodetector array. The body is also moved along the second axis until the slope of the intensity transition profile is maximized, thereby obtaining an in-focus position. The body is then translated along a third axis, substantially orthogonal to the first and the second axes, until the minimum in the intensity transition profile drops to a predetermined percent of the full intensity value.

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Cranbury, NJ, United States of America

Robert L Covey