The measurement of line widths optically allows fast, easy non-contact measurements and finds application in both research and development areas, as well as the production environments There exists presently a. need to increase the measurement accuracy of the width of small lines in the under 10 to 20 micrometer region. As accuracy may be achieved by calibration, there is interest in reducing the measurement variability. One technique of reducing variability, that of using a coherent microscope system that allows spatial filtering of the image of the line being measured, was breadboarded using high contrast etched chromium on glass lines, and degraded line images on film base. A comparison of the estimates of variability for spatially filtered, and unfiltered images, indicated a significant improvement was found for each of the lines measured, with improvements by as much as a factor of four found by the system used. Thus, the investigation of the technique of spatially filtering the images of small lines to reduce the variability of line width measurement, suggest interest is warranted in using the technique if the appropriate microscope objectives allowing access to the Fourier transform plane to facilitate spatial filtering become commercially available.

Library of Congress Subject Headings

Optical measurements; Optical pattern recognition

Publication Date


Document Type


Department, Program, or Center

School of Photographic Arts and Sciences (CIAS)


Carson, John


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