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Proceedings Paper

High Speed Pattern Inspection System
Author(s): Burton D. Figler
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Paper Abstract

In many industrial applications, inspection and quality control is required for two-dimensional patterns on flat surfaces. This paper describes a computer controlled pattern inspection system capable of resolutions and positional accuracies in the 1 to 2 mil range. For sample sizes up to 48-inches in length and up to 4-inches in width, total inspection is accomplished within 50-seconds. Inspected patterns are compared, in real time, with a computer stored master pattern. The system is designed to store up to 60 patterns in disk memory and can swap patterns within 10-seconds. During the inspection, the data on the measured pattern is continuously checked against preselected tolerances. Out of tolerance conditions are immediately flagged, permitting the inspection to be terminated and the sample to be rejected. Pattern sensing is performed with a 2048-element CCD silicon detector array. The CCD signals are amplified and thresholded in a high speed AGC amplifier. The analog signals are then digitized in a 6-bit A/D flash converter. Thereafter, signal processing is performed digitally. Illumination is provided by a 300-watt tungsten-halogen linear filament lamp, used in conjunction with a cylindrical lens condenser. Both the illumination and the projected image of the CCD array span a 4-inch field. The illuminator and sensor are mounted on a carriage that rides on a precision air bearing table. A velocity controlled D.C. servo, accurate to 0.01%, is used to drive the carriage along the long axis of the pattern to provide up to 48-inches of coverage at speeds of up to 1-inch per second. A linear glass scale optical encoder reads carriage position to an accuracy of better than 1-mil.

Paper Details

Date Published: 17 March 1983
PDF: 8 pages
Proc. SPIE 0359, Applications of Digital Image Processing IV, (17 March 1983); doi: 10.1117/12.965976
Show Author Affiliations
Burton D. Figler, Aerodyne Research, Inc. (United States)

Published in SPIE Proceedings Vol. 0359:
Applications of Digital Image Processing IV
Andrew G. Tescher, Editor(s)

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